Re: [PATCH 1/1] media: m2m-deinterlace: replace direct ->device_prep*() calls with standard DMA engine API

[Frank Li]

On Thu, Sep 17, 2026 at 11:37:25PM +0300, Laurent Pinchart wrote:
> On Thu, Sep 17, 2026 at 03:33:57PM -0500, Frank Li wrote:
> > On Thu, Sep 17, 2026 at 11:29:31PM +0300, Laurent Pinchart wrote:
> > > On Thu, Sep 17, 2026 at 03:04:16PM -0400, Frank.Li@xxxxxxxxxxx wrote:
> > > > From: Frank Li <Frank.Li@xxxxxxx>
> > > >
> > > > DMA engine consumers must not call the channel's device_prep_*() function
> > > > pointers directly. Use the standard dmaengine wrapper APIs instead.
> > > >
> > > > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > >
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > >
> > > I've checked the other DMA operations, and there are a few direct
> > > callers of .device_prep_dma_memcpy() and .device_prep_slave_sg(). The
> > > former should be easy to address, as the dmaengine_prep_dma_memcpy()
> > > wrapper is a drop-in replacement. The latter may be a bit more
> > > complicated.
> > >
> > > Any volunteer to send patches ? :-)
> >
> > I already sent out and try to cleanup all.
>
> Thank you. A patch for checkpatch.pl to warn about new callers may also
> be interesting.

Long term plan to move dmaengine callback to private header, build will
failure if consumer try to access dmaengine device.

Frank

>
> > > > ---
> > > >  drivers/media/platform/m2m-deinterlace.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/media/platform/m2m-deinterlace.c b/drivers/media/platform/m2m-deinterlace.c
> > > > index 9dcc4bd6cbdd5..57a91ff2269f2 100644
> > > > --- a/drivers/media/platform/m2m-deinterlace.c
> > > > +++ b/drivers/media/platform/m2m-deinterlace.c
> > > > @@ -330,7 +330,7 @@ static void deinterlace_issue_dma(struct deinterlace_ctx *ctx, int op,
> > > >  	ctx->xt->dst_sgl = true;
> > > >  	flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> > > >
> > > > -	tx = dmadev->device_prep_interleaved_dma(chan, ctx->xt, flags);
> > > > +	tx = dmaengine_prep_interleaved_dma(chan, ctx->xt, flags);
> > > >  	if (tx == NULL) {
> > > >  		v4l2_warn(&pcdev->v4l2_dev, "DMA interleaved prep error\n");
> > > >  		return;
>
> --
> Regards,
>
> Laurent Pinchart