System and its operation method

Abstract

A system includes a first device including a first transmitter and a first receiver, and a second device including a second transmitter and a second receiver and configured to communicate with the first device. The two devices perform a first equalization operation by performing a first phase in which the first receiver performs a signal tuning operation on the second transmitter, a second phase in which the second receiver performs a signal tuning operation on the first transmitter, and one or more other phases. The first phase, the second phase, and the other phases can constitute all phases of the first equalization operation, and some of the other phases can precede the first phase and the second phase. In response to detecting an error after the first equalization operation, the two devices can perform a second equalization operation by performing the first phase, the second phase, or both, without performing the other phases.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2022-0061017, filed with the Korean Intellectual Property Office on May 18, 2022, and Korean Patent Application No. 10-2022-0080852, filed on June 30, 2022, both of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a system, and more specifically, to a data processing system. Background Technology

[0004] Recently, the paradigm of the computing environment is shifting towards ubiquitous computing, enabling computer systems to be used anytime, anywhere. Consequently, the use of portable electronic devices such as mobile phones, digital cameras, and laptops is rapidly increasing. These portable electronic devices typically utilize memory systems, or data storage devices. Memory systems serve as either primary or secondary storage for data processing systems in portable electronic devices.

[0005] When a memory system lacks mechanical drive components, it not only possesses excellent stability and durability but also boasts advantages such as extremely fast information access speeds and low power consumption. Memory systems with these advantages include Universal Serial Bus (USB) memory devices, memory cards with various interfaces, and solid-state drives (SSDs).

[0006] SSDs can use a high-speed non-volatile memory (NVMe) interface based on high-speed peripheral component interconnect (PCIe) as a high-speed interface to connect to the host. Summary of the Invention

[0007] Various embodiments are intended to provide a system and its operating method capable of rapidly performing balancing and recovery processes by skipping unnecessary phases.

[0008] A system according to embodiments of the present disclosure may include: a first device including a first transmitter and a first receiver; and a second device including a second transmitter and a second receiver and configured to communicate with the first device, wherein the first device and the second device perform a first equalization operation by executing multiple stages, the multiple stages including: a first stage in which the first receiver performs a signal tuning operation on the second transmitter; a second stage in which the second receiver performs a signal tuning operation on the first transmitter; and one or more other stages, and wherein in response to detecting an error after the first equalization operation, the first device and the second device perform a second equalization operation by executing the first stage, the second stage, or both, without executing one or more other stages.

[0009] The operating system method according to embodiments of the present disclosure includes an operating method for a system comprising a first device having a first transmitter and a first receiver, and a second device having a second transmitter and a second receiver, and the method may include: the first device and the second device performing a first equalization operation by executing multiple stages, the multiple stages including: a first stage in which the first receiver performs a signal tuning operation on the second transmitter; a second stage in which the second receiver performs a signal tuning operation on the first transmitter; and one or more other stages; and in response to an error being detected after the first equalization operation, the first device and the second device performing a second equalization operation by executing the first stage, the second stage, or both, without executing one or more other stages.

[0010] The system and its operating method according to embodiments of this disclosure can quickly perform balancing operations and recovery processes by skipping unnecessary stages. Attached Figure Description

[0011] Figure 1 This is a block diagram illustrating a system according to an embodiment of the present disclosure.

[0012] Figure 2 The process of performing the first equalization operation and the second equalization operation according to embodiments of the present disclosure is illustrated schematically.

[0013] Figure 3 The process of performing a recovery procedure from a first state to a fifth state according to an embodiment of the present disclosure is illustrated.

[0014] Figure 4 The execution from stage 0 to stage 3 according to embodiments of the present disclosure is illustrated. Figure 2 The process of the first equalization operation in the first recovery process.

[0015] Figure 5The process of a higher-level device and a lower-level device checking the current stage and proceeding to the next stage by means of stage information is illustrated according to an embodiment of the present disclosure.

[0016] Figure 6 This is a flowchart illustrating the process of performing a second recovery process, including a second equalization operation, according to an embodiment of the present disclosure. Detailed Implementation

[0017] In this disclosure, advantages, features, and techniques for implementing them will become more apparent after reading the following illustrative embodiments in conjunction with the accompanying drawings. However, this disclosure may be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to describe this disclosure in detail so that those skilled in the art to which this disclosure pertains can readily implement the technical concepts of this disclosure.

[0018] The embodiments disclosed herein are not limited to the details shown in the accompanying drawings, which are not necessarily drawn to scale, and in some cases, the scale may have been exaggerated to more clearly depict certain features of the disclosure. Although specific terminology is used herein, it should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the disclosure.

[0019] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. When an element is referred to as “on another element,” “connected to,” or “attached to” another element, it may be located directly on, connected to, or attached to the other element, or there may be an intermediate element present. As used herein, the singular form is also intended to include the plural form unless the context clearly indicates otherwise. When the terms “comprising” and / or “including” are used in the specification, it specifies the presence of at least one of the stated features, steps, operations, and / or elements, but does not preclude the presence or addition of one or more other features, steps, operations, and / or elements.

[0020] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0021] Figure 1 This is a block diagram illustrating a system 10 according to an embodiment of the present disclosure.

[0022] System 10 may include a first device D1 and a second device D2. The first device D1 and the second device D2 can exchange signals with each other and execute a preset process.

[0023] The first device D1 may include a first transmitter TX1 and a first receiver RX1. The first transmitter TX1 can transmit a first signal to the second receiver RX2 of the second device D2. The first receiver RX1 can receive the second signal transmitted from the second transmitter TX2 of the second device D2.

[0024] The second device D2 may include a second transmitter TX2 and a second receiver RX2. The second transmitter TX2 can send a second signal to the first receiver RX1 of the first device D1. The second receiver RX2 can receive the first signal sent from the first transmitter TX1 of the first device D1.

[0025] The first device D1 and the second device D2 can communicate with each other based on protocols such as: Universal Serial Bus (USB) protocol, Universal Flash Memory (UFS) protocol, Multimedia Card (MMC) protocol, Parallel Advanced Technology Attachment (PATA) protocol, Serial Advanced Technology Attachment (SATA) protocol, Small Computer System Interface (SCSI) protocol, Serial SCSI (SAS) protocol, Peripheral Component Interconnect (PCI) protocol, or High Speed ​​PCI (PCI-E) protocol.

[0026] The first device D1 can be an upper-layer device, a downstream port, or a root complex. The first device D1 can be a host device connected to a storage system such as an SSD. The second device D2 can be a lower-layer device, an upstream port, an endpoint, or a storage system.

[0027] The first device D1 and the second device D2 can perform a recovery process according to the communication specifications. To optimize signal characteristics, a recovery process can be performed between the first device D1 and the second device D2. The recovery process can be performed to change, for example, the communication speed between the first device D1 and the second device D2. The recovery process can be performed to change, for example, the path structure between the first device D1 and the second device D2. For example, when a link error occurs between the first device D1 and the second device D2, a recovery process can be performed. For example, when the first device D1 determines that a recovery process is needed, the recovery process can be performed according to the selection made by the first device D1.

[0028] When a recovery process is performed to change the communication speed, the recovery process may include equalization operations to ensure signal quality between the first device D1 and the second device D2.

[0029] The initial equalization operation can be performed by executing all of the multiple stages defined in the communication specification. The initial equalization operation may include the first equalization operation performed after system 10 is powered on. The initial equalization operation may also include an equalization operation performed after a predetermined time has elapsed following a previously performed equalization operation. The initial equalization operation may be referred to as the first equalization operation.

[0030] Non-initial balancing operations can be performed as a response to errors that subsequently occur after the initial balancing operation. Non-initial balancing operations can be performed by executing one or more necessary stages from a plurality of stages, without executing all stages. Non-initial balancing operations may include balancing operations executed within a predetermined time period immediately following the previously executed balancing operation. Non-initial balancing operations may be referred to as second balancing operations.

[0031] Specifically, the first device D1 and the second device D2 can perform a first equalization operation that executes all stages of a predetermined plurality of stages. Among the plurality of stages, the first stage may be the stage where the first receiver RX1 performs a signal tuning operation on the second transmitter TX2, and the second stage may be the stage where the second receiver RX2 performs a signal tuning operation on the first transmitter TX1. Here, "first stage" and "second stage" are merely names of two stages among the plurality of stages and do not imply the execution order within the plurality of stages. That is, during the initial equalization operation, the first stage and the second stage are not necessarily the first and second stages executed among the plurality of stages, and other stages among the plurality of stages may be executed before, after, or both before and after the first and second stages. When an error is detected after the first equalization operation, the first device D1 and the second device D2 can perform a second equalization operation that executes only the first stage, the second stage, or both of the plurality of stages. In the second equalization operation, the first device D1 and the second device D2 may skip one or more stages among the plurality of stages other than the first stage, the second stage, or both of the plurality of stages.

[0032] According to an embodiment, other stages skipped in the second balancing operation may include a stage in which the first device D1 and the second device D2 share initial settings and variables before the first and second stages executed in the first balancing operation. According to an embodiment, when the first stage, the second stage, or both are executed in the second balancing operation, both the first device D1 and the second device D2 may apply the initial settings and variables shared in the first balancing operation.

[0033] According to an embodiment, the first device D1 and the second device D2 can execute these stages by exchanging stage information that indicates any one of the multiple stages.

[0034] According to an embodiment, when the first receiver RX1 detects an error after the first equalization operation, the first device D1 can determine to perform a first phase in the second equalization operation. According to an embodiment, the first device D1 can send phase information indicating the first phase to the second device D2 so that the first phase can be performed in the second equalization operation. According to an embodiment, the second device D2 can determine to perform the first phase in the second equalization operation in response to receiving the phase information indicating the first phase from the first device D1.

[0035] According to an embodiment, when the second receiver RX2 detects an error after the first equalization operation, the second device D2 can determine to perform a second phase in the second equalization operation. According to an embodiment, the second device D2 can send phase information indicating the second phase to the first device D1 so that the second phase can be performed in the second equalization operation. According to an embodiment, the first device D1 can determine to perform the second phase in the second equalization operation in response to receiving the phase information indicating the second phase from the second device D2.

[0036] Figure 2 The diagram schematically illustrates a method for performing a first equalization operation EQ1 and a second equalization operation EQ2 according to an embodiment of the present disclosure.

[0037] Reference Figure 2 It can execute the first recovery procedure RCVR1, which includes the first equalization operation EQ1. All stages of the multiple stages defined in the communication specification can be executed in the first equalization operation EQ1.

[0038] After the first recovery process RCVR1, which includes the first equalization operation EQ1, is completed, the first receiver RX1 of the first device D1, the second receiver RX2 of the second device D2, or both, can detect an error. In response to the detected error, the second recovery process RCVR2 can be executed. In an embodiment, in the second equalization operation EQ2 executed in the second recovery process RCVR2, unnecessary stages can be skipped, and only necessary stages can be executed. For example, a stage skipped in the second equalization operation EQ2 could be the stage where the first device D1 and the second device D2 share the initial setting value and the variable SV. Because the initial setting value and the variable SV have already been shared during the first equalization operation EQ1, they can be applied as is without needing to be shared again in the second equalization operation EQ2.

[0039] According to the embodiment, even if an error is detected again after the second recovery process RCVR2 is completed and the nth (n>2) recovery process and the nth equalization operation are repeated, the nth equalization operation can be performed in a similar manner to the second equalization operation EQ2.

[0040] The execution time T2 of the second equalization operation EQ2, which skips unnecessary stages, can be shorter than the execution time T1 of the first equalization operation EQ1. Therefore, because the second recovery process RCVR2 executes faster than the first recovery process RCVR1, the overall operational performance of system 10 can be improved.

[0041] Figure 3 This is a diagram illustrating the process of performing a recovery procedure from a first state S1 to a fifth state S5 according to an embodiment of the present disclosure. Figure 2 The first recovery process RCVR1 and the second recovery process RCVR2 can be based on Figure 3 The process shown will be executed.

[0042] Reference Figure 3 The first state S1 can be the first state in the recovery process. In the first state S1, the first receiver RX1 of the first device D1 and the second receiver RX2 of the second device D2 can check whether the received data packets can be correctly identified. In the first state S1, the first device D1 and the second device D2 can determine the task to be executed in the current recovery process (e.g., communication speed change task, path structure change task, etc.). When it is determined that the communication speed change task will be executed, the recovery process can enter the second state S2 under the control of the first device D1.

[0043] The second state S2 can be the state in which the first device D1 and the second device D2 set a new speed through an equalization operation and perform signal tuning operations on the new speed. Specifically, the receiver of each device can adjust and tune the characteristics of the transmitter of the counterpart device through the signal tuning operation. When the second state S2 proceeds without errors, the recovery process can return to the first state S1. When an error occurs in the second state S2 (e.g., a timeout), the recovery process can proceed to the third state S3.

[0044] The third state S3 can be the state in which the first device D1 and the second device D2 return to their original speeds. That is, because an error occurred at the new speed in the second state S2, the first device D1 and the second device D2 can reapply their original speeds. Then, the recovery process can proceed from the third state S3 back to the first state S1.

[0045] The fourth state S4 can be a state for resetting lane-to-lane deskew and re-checking the order of the lanes. When the recovery process returns from the second state S2 or the third state S3 to the first state S1, the recovery process can proceed from the first state S1 to the fourth state S4.

[0046] The fifth state S5 can be a final check to see if the items corrected in the previous state have been properly applied and maintained. When the recovery process terminates after the fifth state S5, the first device D1 and the second device D2 can operate in a normal state (e.g., the L0 state of the PCIe specification).

[0047] According to the embodiment, each of the first state S1 to the fifth state S5 can be Recovery.RcvrLock, Recovery.Equalization, Recovery.Speed, Recovery.RcvrCfg and Recovery.Idle respectively, according to the Link Training State Machine (LTSSM) of the PCIe specification.

[0048] Figure 4 This illustrates the execution from stage 0 (P0) to stage 3 (P3) according to an embodiment of the present disclosure. Figure 2 A diagram illustrating the process of the first equalization operation EQ1 in the first recovery process of RCVR1.

[0049] Phase 0 (P0) through Phase 3 (P3) can be all of the multiple phases of the equalization operation defined according to the communication specification. Therefore, when the first equalization operation EQ1 (i.e., the initial equalization operation) is performed, all phases from Phase 0 (P0) to Phase 3 (P3) can be executed.

[0050] Specifically, in the first state S1 of the first recovery process RCVR1, the first device D1 can determine to enter the second state S2 to perform a communication speed change task. The first device D1 can control the first recovery process RCVR1 to enter the second state S2 by, for example, setting the start_equalization_w_preset value of the PCIe specification to 1b.

[0051] In the second state S2, the first device D1 and the second device D2 can perform the first equalization operation EQ1. The first equalization operation EQ1 can be performed by executing all stages from stage 0 (P0) to stage 3 (P3).

[0052] Specifically, the second device D2 can first enter stage 0 (P0) of the second state S2. The second device D2 can transmit initial settings to the first device D1 in stage 0 (P0) and then enter stage 1 (P1). For example, the initial settings may include an initial transmitter preset and a receiver prompt. The initial settings can be maintained by both the first device D1 and the second device D2 so that they can be applied as is in the subsequent second equalization operation EQ2.

[0053] The first device D1 can first enter phase 1 (P1) of the second state S2. In phase 1 (P1), the first device D1 and the second device D2 can enter phase 2 (P2) after exchanging various predefined variables. For example, the various predefined variables may include full swing and low frequency. The various predefined variables can be maintained by both the first device D1 and the second device D2 so that they can be applied as is in the subsequent second equalization operation EQ2.

[0054] In phase 2 (P2), the second receiver RX2 of the second device D2 can perform a signal tuning operation on the first transmitter TX1 of the first device D1. For example, the second device D2 can request the first transmitter TX1 of the first device D1 to transmit a first signal that can be received by the second receiver RX2 of the second device D2, and determine that the first signal transmitted from the first transmitter TX1 is passed if there are no errors in the signal. When the second device D2 determines that the first signal is passed, the first device D1 and the second device D2 can proceed to phase 3 (P3).

[0055] In phase 3 (P3), the first receiver RX1 of the first device D1 can perform a signal tuning operation on the second transmitter TX2 of the second device D2. For example, the first device D1 can request the second transmitter TX2 of the second device D2 to send a second signal that can be received by the first receiver RX1 of the first device D1, and determine that the second signal sent from the second transmitter TX2 is passed if there are no errors in the signal. When the first device D1 determines that the second signal is passed, it can terminate the first equalization operation EQ1. Then the first recovery process RCVR1 can return from the second state S2 to the first state S1.

[0056] However, as referenced Figure 2 As described, when an error occurs in any of stages 0 (P0) to 3 (P3), the first recovery process RCVR1 can transition from the second state S2 to the third state S3.

[0057] Figure 5 This is a diagram illustrating a method by which a first device D1 and a second device D2, according to an embodiment of the present disclosure, check the current stage and proceed to the next stage in a first equalization operation EQ1 using stage information PI.

[0058] When in the second state S2, the first device D1 and the second device D2 can exchange stage information PI with each other. Stage information PI can be used to notify the other device of the current stage or to proceed to the next stage. As shown in Table TB, for example, stage information PIs of 00b, 01b, 10b, and 11b can correspond to stage 0 (P0), stage 1 (P1), stage 2 (P2), and stage 3 (P3), respectively. For example, stage information PI can be the equalization control (EC) value of the ordered set of training sequence 1 in the PCIe specification.

[0059] Specifically, in operation S110, the second device D2 can send the stage information PI 00b to the first device D1 to notify the first device D1 that the second device D2 is in stage 0 (P0). As described above, the second device D2 can send the initial setting value to the first device D1 during stage 0 (P0).

[0060] In operation S120, for example, the first device D1 may receive an initial setting value from the second device D2, and then send stage information PI 01b to the second device D2 two or more times, causing the second device D2 to enter stage 1 (P1). In response to receiving stage information PI 01b from the first device D1, the second device D2 may enter stage 1 (P1).

[0061] In operation S130, the second device D2 can send stage information PI 01b to the first device D1 to notify the first device D1 that the second device D2 is in stage 1 (P1). As described above, the first device D1 and the second device D2 can exchange various variables with each other in stage 1 (P1).

[0062] In operation S140, for example, each of the first device D1 and the second device D2 may exchange various variables and then send the stage information PI 10b to the other device two or more times in order to enter stage 2 (P2).

[0063] In operation S150, each of the first device D1 and the second device D2 can send phase information PI 10b to the other device to notify the other device that the transmitting device is in phase 2 (P2). As described above, in phase 2 (P2), the second receiver RX2 of the second device D2 can perform a signal tuning operation on the first transmitter TX1 of the first device D1.

[0064] In operation S160, for example, the second device D2 may perform a signal tuning operation on the first transmitter TX1, and then send stage information PI11b to the first device D1 two or more times to enter stage 3 (P3). After sending stage information PI11b to the first device D1, the second device D2 may enter stage 3 (P3). In response to receiving stage information PI11b from the second device D2, the first device D1 may enter stage 3 (P3).

[0065] In operation S170, each of the first device D1 and the second device D2 can send phase information PI 11b to the other device to notify the other device that the first device D1 and the second device D2 are in phase 3 (P3). As described above, in phase 3 (P3), the first receiver RX1 of the first device D1 can perform a signal tuning operation on the second transmitter TX2 of the second device D2.

[0066] In operation S180, for example, the first device D1 may perform a signal tuning operation on the second transmitter TX2, and then send predetermined stage information PI (e.g., stage information PI 00b) to the second device D2 two or more times in order to return to the first state S1 of the recovery process. After sending the stage information PI 00b to the second device D2, the first device D1 may return to the first state S1 of the recovery process. In response to receiving the stage information PI 00b from the first device D1, the second device D2 may return to the first state S1 of the recovery process.

[0067] Figure 6 This illustrates the execution of embodiments according to this disclosure, including... Figure 2 The flowchart illustrates the process of the second recovery procedure RCVR2 in the second equalization operation EQ2. In the second recovery procedure RCVR2, except as indicated below, the execution of states S1 through S5 can be performed in conjunction with reference to... Figure 3 The description is the same.

[0068] After the first recovery process RCVR1, including the first equalization operation EQ1, is completed, the first receiver RX1 of the first device D1, the second receiver RX2 of the second device D2, or both, can detect errors. Therefore, the following can be executed: Figure 2 The second equalization operation EQ2 is the non-initial equalization operation. When performing the non-initial equalization operation, depending on which device(s) need to perform signal tuning operations, only stage 2 (P2), stage 3 (P3), or both of the stages P0 to P3 performed in the first equalization operation EQ1 may be executed.

[0069] More specifically, when stages 0 (P0) and 1 (P1) are executed in the first equalization operation EQ1, the first device D1 and the second device D2 can share initial settings and various variables with each other. Therefore, both the first device D1 and the second device D2 can apply the shared initial settings and various variables in the second equalization operation EQ2. If necessary, the initial settings and various variables can be stored in separate registers for each device. Therefore, stages 0 (P0) and 1 (P1) can be skipped in the second equalization operation EQ2.

[0070] When both the first receiver RX1 of the first device D1 and the second receiver RX2 of the second device D2 detect an error, both phase 2 (P2) and phase 3 (P3) can be executed. Conversely, when only the second receiver RX2 of the second device D2 detects an error, only phase 2 (P2) where the second receiver RX2 performs signal tuning operations can be executed, and phase 3 (P3) can be skipped. When only the first receiver RX1 of the first device D1 detects an error, only phase 3 (P3) where the first receiver RX1 performs signal tuning operations can be executed, and phase 2 (P2) can be skipped. To communicate the phases of the signal tuning operations to be performed, the first device D1 and the second device D2 can exchange phase information PI before entering the second equalization operation EQ2. For example, in response to detecting a first error, the first device D1 can send the phase information PI indicating phase 3 (P3) to the second device D2, and the second device D2 can send the phase information PI indicating phase 2 (P2) to the first device D1 in response to detecting a second error.

[0071] Specifically, in Figure 6 In operation S210, the second recovery process RCVR2 can enter the first state S1.

[0072] In operation S211, the second device D2 can determine whether the stage information PI sent from the first device D1 indicates stage 3 (P3) (i.e., 11b). When the stage information PI indicates stage 3 (P3), the process can proceed to operation S212. When the stage information PI does not indicate stage 3 (P3), the process can proceed to operation S213.

[0073] In operation S212, the first device D1 can determine whether the stage information PI sent from the second device D2 indicates stage 2 (P2) (i.e., 10b). When the stage information PI indicates stage 2 (P2), the process can proceed to operation S221. When the stage information PI does not indicate stage 2 (P2), the process can proceed to operation S223.

[0074] In operation S213, the first device D1 can determine whether the stage information PI sent from the second device D2 indicates stage 2 (P2) (i.e., 10b). When the stage information PI indicates stage 2 (P2), the process can proceed to operation S224. When the stage information PI does not indicate stage 2 (P2), the process can proceed to operation S250.

[0075] In operation S220, the second recovery process RCVR2 can enter the second state S2 corresponding to the second equalization operation (EQ2).

[0076] In operation S221, the first device D1 and the second device D2 can enter phase 2 (P2). This can be referred to as... Figure 4 and Figure 5 The process executes stage 2 (P2) as described. If no error occurs in stage 2 (P2), the process can proceed to operation S222. If an error occurs in stage 2 (P2), the process can proceed to operation S230.

[0077] In operation S222, the first device D1 and the second device D2 can enter stage 3 (P3). See reference... Figure 4 and Figure 5 The process executes stage 3 (P3) as described. If no error occurs in stage 3 (P3), the process can proceed to operation S240. If an error occurs in stage 3 (P3), the process can proceed to operation S230.

[0078] In operation S223, the first device D1 and the second device D2 can enter stage 3 (P3). See reference... Figure 4 and Figure 5 The process executes stage 3 (P3) as described. If no error occurs in stage 3 (P3), the process can proceed to operation S240. If an error occurs in stage 3 (P3), the process can proceed to operation S230.

[0079] In operation S224, the first device D1 and the second device D2 can enter phase 2 (P2). See reference... Figure 4 and Figure 5 The process executes stage 2 (P2) as described. If no error occurs in stage 2 (P2), the process can proceed to operation S240. If an error occurs in stage 2 (P2), the process can proceed to operation S230.

[0080] In operation S230, as referred to Figure 3 As described, the second recovery process RCVR2 can enter the third state S3.

[0081] In operation S240, as referred to Figure 3As described, the second recovery process RCVR2 can enter the first state S1.

[0082] In operation S250, as referred to Figure 3 As described, the second recovery process RCVR2 can enter the fourth state S4.

[0083] In operation S260, as referred to Figure 3 As described, the second recovery process RCVR2 can enter the fifth state S5.

[0084] In this embodiment, the order of operations S211 and S212 can be the same as... Figure 6 The order shown is the reverse.

[0085] In summary, when the second equalization operation EQ2 is executed after the first equalization operation EQ1, unnecessary stages among all the stages executed in the first equalization operation EQ1 can be skipped, and only necessary stages can be selectively executed. Before entering the second equalization operation EQ2, each of the first device D1 and the second device D2 can easily and efficiently notify the other (other) device of the necessary stages by exchanging stage information PI. Therefore, the recovery process can be executed quickly, and the possibility of timeout can be minimized.

[0086] It will be understood by those skilled in the art that the present invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. Therefore, it should be understood that the above embodiments are exemplary in all respects and not restrictive. The scope of this disclosure is defined by the appended claims rather than the detailed descriptions, and it should be understood that the meaning and scope of the claims, as well as all changes or modifications derived from their equivalents, are included within the scope of this disclosure.

Claims

1. A system comprising: a first device comprising a first transmitter and a first receiver; and a second device comprising a second transmitter and a second receiver and in communication with the first device, wherein the first device and the second device perform a first equalization operation by executing a plurality of stages, the plurality of stages comprising: a first stage in which the first receiver performs a signal tuning operation on the second transmitter; a second stage in which the second receiver performs a signal tuning operation on the first transmitter; and one or more other stages; and in response to detecting an error after the first equalization operation, the first device and the second device perform a second equalization operation by: performing the first stage, the second stage, or both the first stage and the second stage, and not performing the one or more other stages. the first stage, the second stage, and the one or more other stages comprise all stages performed in a first equalization operation, and none of the one or more other stages are performed in the second equalization operation.

2. The system of claim 1, wherein, the one or more other stages comprise a stage in which the first device and the second device share initial setting values and variables prior to performing the first stage and the second stage in the first equalization operation.

3. The system of claim 2, wherein, when at least one of the first stage and the second stage is performed in the second equalization operation, the first device and the second device both apply the initial setting values and the variables shared in the first equalization operation.

4. The system of claim 3, wherein, the first device and the second device perform the plurality of stages by exchanging stage information indicative of any one of the plurality of stages.

5. The system of claim 1, wherein, in response to the first receiver detecting an error after the first equalization operation, the first device determines to perform the first stage in the second equalization operation.

6. The system of claim 1, wherein, the first device transmits stage information indicative of the first stage to the second device in order to perform the first stage in the second equalization operation.

7. The system of claim 6, wherein, the second device determines to perform the first stage in the second equalization operation based on the stage information.

8. The system of claim 7, wherein, in response to the second receiver detecting an error after the first equalization operation, the second device determines to perform the second stage in the second equalization operation.

9. The system of claim 1, wherein, the second device transmits stage information indicative of the second stage to the first device in order to perform the second stage in the second equalization operation.

10. The system of claim 9, wherein, the first device determines to perform the second stage in the second equalization operation based on the stage information.

11. The system of claim 10, wherein, 12. A method of operating a system, the system comprising a first device and a second device, the first device comprising a first transmitter and a first receiver, the second device comprising a second transmitter and a second receiver, the method comprising: performing, by the first device and the second device, a first equalization operation by executing a plurality of stages, the plurality of stages comprising: a first stage in which the first receiver performs a signal tuning operation on the second transmitter; ​ a second stage in which the second receiver performs a signal tuning operation on the first transmitter; and one or more other stages; and in response to detecting an error after the first equalization operation, performing, by the first device and the second device, a second equalization operation by: performing the first stage, the second stage, or both the first stage and the second stage, and not performing the one or more other stages.

13. The method of claim 12, wherein, the first stage, the second stage, and the one or more other stages constitute all stages performed in the first equalization operation, and none of the one or more other stages is performed in the second equalization operation.

14. The method of claim 13, wherein, the one or more other stages include one or more stages in which the first device and the second device share initial setting values and variables prior to performing the first stage and the second stage in the first equalization operation.

15. The method of claim 14, wherein, performing the second equalization operation includes: when performing at least one of the first stage and the second stage, applying, by the first device and the second device, the initial setting values and the variables shared in the first equalization operation.

16. The method of claim 12, further comprising: in response to the first receiver detecting an error after the first equalization operation, determining, by the first device, to perform the first stage in the second equalization operation.

17. The method of claim 16, further comprising: sending, by the first device, stage information indicating the first stage to the second device for performing the first stage in the second equalization operation.

18. The method of claim 12, further comprising: in response to the second receiver detecting an error after the first equalization operation, determining, by the second device, to perform the second stage in the second equalization operation.

19. The method of claim 18, further comprising: sending, by the second device, stage information indicating the second stage to the first device for performing the second stage in the second equalization operation.

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