On Thu, Oct 08, 2026 at 11:53:44AM +0530, Kishore Batta wrote: > Hi All, > > This series reworks the Sahara protocol driver to make it reusable for > multiple MHI based devices and adds support for capturing, restoring and > exposing DDR training data using the Sahara command mode. > > The Sahara protocol is transported over the MHI bus and is used by multiple > flashless devices to transfer firmware images, retrieve memory dumps and > exchange command mode data during early boot. However, the current > implementation lives under the QAIC accelerator driver and contains > device-specific assumptions that limit reuse. > > Some MHI devices (for example, QDU100) expose the sahara protocol directly > on a "SAHARA" MHI channel and rely on command mode to exchange DDR training > data with the host. The existing driver does not bind to such devices and > ignores Sahara command mode packets, causing training data to be dropped. > > This series addresses these issues by relocating the Sahara driver to the > MHI subsystem, centralizing device specific configuration and adding command > mode handling for DDR training data. > > Overview of the changes in this series - > 1. Move Sahara under the MHI subsystem: > a. Relocate the sahara protocol driver from QAIC accelerator tree to > drivers/bus/mhi/host/clients directory. > b. Register Sahara as an independent MHI protocol driver. > > 2. Generalize device matching and configuration > a. Allow the driver to bind to devices exposing the protocol on a > SAHARA MHI channel. > b. Centralize firmware image table selection at probe time using a variant > table, instead of scattered conditionals. > c. Preserve existing behavior on AIC devices. > > 3. Add QDU100 firmware image table support > a. Add a QDU100 image table and select it based on the matched MHI channel. > b. No separate client driver or registration mechanism is required. > > 4. Add Sahara command mode support for DDR training. > a. Handle command mode packets(CMD_READY, EXECUTE, EXECUTE_DATA). > b. Query supported commands and retrieve DDR training data from the device. > c. Allocate receive buffers based on the reported payload size and copy > raw data from the MHI DL. > d. Store training data in controller-scoped memory using devres so it > survives sahara channel teardown. > > 5. Expose DDR training data to userspace > a. Add a read-only binary sysfs attribute under the MHI controller device. > b. The attribute reads directly from controller-scoped storage and remains > available after the Sahara channel device is removed. > c. Cleanup is handled automatically via device-managed resources. > > 6. Document the sysfs ABI > a. Add ABI documentation describing the DDR training data sysfs node. > > Signed-off-by: Kishore Batta <[email protected]>
Series fails to apply to mhi-next branch. Please rebase and resend. Since I'm about to send the PR for v7.4, this will miss the upcoming cycle. But I can queue it once v7.4-rc1 is released. - Mani -- மணிவண்ணன் சதாசிவம்
