On 15-11-21, 11:21, Arnd Bergmann wrote:

On Mon, Nov 15, 2021 at 10:14 AM Laurent Pinchart
[off-list ref] wrote:

quoted

On Mon, Nov 15, 2021 at 09:54:00AM +0100, Arnd Bergmann wrote:

quoted

@@ -1285,11 +1287,13 @@ static int xilinx_dpdma_config(struct dma_chan *dchan,
      spin_lock_irqsave(&chan->lock, flags);

      /*
-      * Abuse the slave_id to indicate that the channel is part of a video
-      * group.
+      * Abuse the peripheral_config to indicate that the channel is part

Is it still an abuse, or is this now the right way to pass custom data
to the DMA engine driver ?

It doesn't make the driver any more portable, but it's now being
more explicit about it. As far as I can tell, this is the best way
to pass data that cannot be expressed through the regular interfaces
in DT and the dmaengine API.

Ideally there would be a generic way to pass this flag, but I couldn't
figure out what this is actually doing, or whether there is a better
way. Maybe Vinod has an idea.

I'll change s/Abuse/Use/ for the moment until I get a definite answer.

I would feel this is still not use for the peripheral_config, but lets
keep it to get rid of slave_id.

Also, I would be better if this was moved to DT as the next cell, don't
recall why that was not done/feasible.

-- 
~Vinod

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