Re: [PATCH v6 7/7] bus: mhi: Expose DDR training data via controller sysfs

On Mon, Jul 13, 2026 at 01:00:27PM +0530, Kishore Batta wrote:
> 
> On 7/9/2026 12:27 PM, Manivannan Sadhasivam wrote:
> > On Wed, Jul 01, 2026 at 04:07:41PM +0530, Kishore Batta wrote:
> > > DDR training data captured during Sahara command mode needs to be
> > > accessible to userspace so it can be persisted and reused on subsequent
> > > boots. Currently, the training data is stored internally in the driver
> > > but has no external visibility once the Sahara channel is torn down.
> > > 
> > > Expose the captured DDR training data via a read-only binary sysfs
> > > attribute on the MHI controller device:
> > > 
> > > /sys/bus/mhi/devices/<mhi_cntrl>/ddr_training_data
> > > 
> > > The sysfs read callback serves data directly from controller scoped storage
> > > and protects access with the controller training data lock. The attribute
> > > lifetime is tied to the controller device via devres, allowing the data to
> > > remain readable after Sahara channel teardown and ensuring automatic
> > > cleanup when controller device is removed.
> > > 
> > If this training data is RO, then what is the use of exposing it to userspace?
> > 
> > - Mani
> 
> The userspace component will read this from sysfs and save it to a file
> named mdmddr_0x<serial_no>.mbn.
> 

You need to mention the exact file name for the read data.

- Mani

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