Re: [PATCH v6 4/7] bus: mhi: Add QDU100 Sahara variant and firmware fallback

[Manivannan Sadhasivam]

On Mon, Jul 13, 2026 at 12:55:52PM +0530, Kishore Batta wrote:
> 
> On 7/9/2026 11:49 AM, Manivannan Sadhasivam wrote:
> > On Wed, Jul 01, 2026 at 04:07:38PM +0530, Kishore Batta wrote:
> > > The Sahara driver currently selects a firmware image table based on the
> > > attached device, but it does not recognize QDU100 devices that expose the
> > > protocol on the SAHARA MHI channel. As a result, the host cannot associate
> > > QDU100 devices with the correct firmware namespace during image transfer.
> > > 
> > > Extend the probe time variant selection to match the SAHARA MHI channel and
> > > associate it with the QDU100 firmware folder. Add a firmware lookup
> > > fallback for cases where an image does not have an explicit entry in the
> > > device's firmware table. This allows required images to be provisioned by
> > > the platform.
> > > 
> > > This change only affects devices matched on the SAHARA MHI channel and
> > > does not change behavior for existing AIC100 and AIC200 devices.
> > > 
> > > Signed-off-by: Kishore Batta <kishore.batta@xxxxxxxxxxxxxxxx>
> > > ---
> > >   drivers/bus/mhi/host/clients/sahara/sahara.c | 27 +++++++++++++++--
> > >   drivers/bus/mhi/host/pci_generic.c           | 45 ++++++++++++++++++++++++++++
> > >   2 files changed, 70 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/bus/mhi/host/clients/sahara/sahara.c b/drivers/bus/mhi/host/clients/sahara/sahara.c
> > > index e339c67e236af271645ca81cc517efd9eead87e4..9adbd84859073d8024ba2a5fcfa33897439d6759 100644
> > > --- a/drivers/bus/mhi/host/clients/sahara/sahara.c
> > > +++ b/drivers/bus/mhi/host/clients/sahara/sahara.c
> > > @@ -189,6 +189,7 @@ static bool is_streaming(struct sahara_context *context)
> > >   static int sahara_find_image(struct sahara_context *context, u32 image_id)
> > >   {
> > > +	char *fw_path;
> > >   	int ret;
> > >   	if (image_id == context->active_image_id)
> > > @@ -201,8 +202,28 @@ static int sahara_find_image(struct sahara_context *context, u32 image_id)
> > >   	}
> > >   	if (image_id >= context->table_size || !context->image_table[image_id]) {
> > > -		dev_err(&context->mhi_dev->dev, "request for unknown image: %d\n", image_id);
> > > -		return -EINVAL;
> > > +		if (!context->fw_folder) {
> > > +			dev_err(&context->mhi_dev->dev,
> > > +				"Request for unknown image: %u (no fw folder)\n", image_id);
> > > +			return -EINVAL;
> > > +		}
> > > +
> > > +		fw_path = kasprintf(GFP_KERNEL, "qcom/%s/%u",
> > > +				    context->fw_folder, image_id);
> > > +		if (!fw_path)
> > > +			return -ENOMEM;
> > > +
> > > +		ret = firmware_request_nowarn(&context->firmware,
> > > +					      fw_path,
> > > +					      &context->mhi_dev->dev);
> > > +		kfree(fw_path);
> > > +		if (ret) {
> > > +			dev_err(&context->mhi_dev->dev,
> > > +				"request for unknown image: %d\n", image_id);
> > > +			return -EINVAL;
> > > +		}
> > > +		context->active_image_id = image_id;
> > > +		return 0;
> > >   	}
> > >   	/*
> > > @@ -870,8 +891,10 @@ static void sahara_mhi_dl_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result
> > >   static const struct mhi_device_id sahara_mhi_match_table[] = {
> > >   	{ .chan = "QAIC_SAHARA", },
> > > +	{ .chan = "SAHARA"},
> > >   	{},
> > >   };
> > > +MODULE_DEVICE_TABLE(mhi, sahara_mhi_match_table);
> > This change should belong to a separate patch.
> 
> There was a review comment from Jeff(v4, patch 3) to move to this change to
> the patch which adds QDU100 support so that it doesn't break bisect. Please
> let me know if i need to move it to a separate patch altogether ?
> 

Since it is a new device support for Sahara, bisect is not really a problem. But
I do see a value in keeping everything in a single patch.

- Mani

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