UFS Host Controller Link Manager Daisy-Chain Control
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Solution Overview
Problem
Conventional UFS link control mechanisms are inconsistent across daisy-chained devices, leading to complexity and error-proneness in device drivers, as they must handle different link control mechanisms, making it difficult for a UFS host to manage multiple devices connected in a daisy-chain configuration.
Innovation Solution
A host system with a link manager and communication interface that allows device drivers to issue uniform link control messages and data/management commands, treating all daisy-chained devices as if they are point-to-point connected, simplifying the control process by bypassing the link manager for subsequent links and using standardized commands for consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional UFS link control mechanisms are used for daisy-chained devices, then the host can control the first link directly, but the host cannot directly control subsequent links, requiring different control mechanisms for different links
Solution Approach 1:
The first UFS device acts as an intermediary for link control of subsequent links. The host controller sends link control commands to the first device, which then forwards them to the second device through the second link. This mediator approach allows uniform link control messaging while enabling indirect control of downstream links, resolving the contradiction between operational simplicity and control capability.
2Adaptability or versatility
If different link control mechanisms are implemented for different links in daisy-chain configuration, then the host can control both first and subsequent links, but the device drivers become complex and error-prone
Solution Approach 1:
The first UFS device is designed with universal functionality to handle both data/management commands from the host and link control commands for subsequent links. It can receive link control messages from the host controller and forward them appropriately to the second device, while also processing normal data operations. This multi-functionality enables the host to use a single uniform control mechanism for all links, improving reliability by eliminating the need for complex, error-prone differentiated control logic in device drivers.
3Ease of operation
If the host relies on the first device to control the second link through D/M commands, then the second link can be controlled indirectly, but the link control is not consistent across different links
Solution Approach 1:
The control architecture is segmented into two distinct functional paths: a direct control path for the first link where the host controller communicates directly with the first device, and an indirect control path for subsequent links where the first device acts as a relay. This segmentation allows each path to be optimized independently while maintaining overall system consistency through standardized link control messaging, reducing the complexity of the overall control architecture.
Data Source
AI summary
In conventional systems with a plurality of UFS devices daisy-chained to a UFS host, a UFS device driver must be able to differentiate among the links, and send either link control messages or data/management (D/M) messages to a UFS host controller. This can make force the UFS device driver to be complicated and error prone. To address this issue, a host controller can provide a uniform view of a plurality of daisy-chained devices to a device driver of a host. For example, the host controller can be such that from the perspective of the device driver, each device can appear to be a point-to-point connected device. This can allow the device driver to use a same set of link control messages to control the links. In this way, the device driver can be simplified and thus less error prone.