Re: [PATCH v4 9/9] Documentation: ABI: Add sysfs ABI documentation for DDR training data

From: Kishore Batta

Date: Tue Apr 14 2026 - 05:57:33 EST


On 4/13/2026 5:29 PM, Manivannan Sadhasivam wrote:
On Thu, Mar 19, 2026 at 12:01:49PM +0530, Kishore Batta wrote:
Add ABI documentation for the DDR training data sysfs attribute exposed by
the sahara MHI driver.

The documented sysfs node provides read-only access to the DDR training
data captured during sahara command mode and exposed via the MHI
controller device. This allows userspace to read the training data and
manage it as needed outside the kernel.

Signed-off-by: Kishore Batta <kishore.batta@xxxxxxxxxxxxxxxx>
Ah, this should be squashed with previous patch.

- Mani
Sure. I will do it.
---
.../ABI/testing/sysfs-bus-mhi-ddr_training_data | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data b/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data
new file mode 100644
index 0000000000000000000000000000000000000000..810b487b5a5fdba133d81255f9879844e3938a10
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data
@@ -0,0 +1,19 @@
+What: /sys/bus/mhi/devices/<mhi-cntrl>/ddr_training_data
+
+Date: March 2026
+
+Contact: Kishore Batta <kishore.batta@xxxxxxxxxxxxxxxx>
+
+Description: Contains the DDR training data for the Qualcomm device
+ connected. MHI driver populates different controller
+ nodes for each device. The DDR training data is exposed
+ to userspace to read and save the training data file to
+ the filesystem. In the subsequent boot up of the device,
+ the training data is restored from host to device
+ optimizing the boot up time of the device.
+
+Usage: Example for reading DDR training data:
+ cat /sys/bus/mhi/devices/mhi0/ddr_training_data
+
+Permissions: The file permissions are set to 0444 allowing read
+ access.

--
2.34.1