Re: [PATCHv2] omap-dma/omap_vout_vrfb: fix off-by-one fi value

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Fri, 9 Aug 2019 10:32:40 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> The OMAP 4 TRM specifies that when using double-index addressing
> the address increases by the ES plus the EI value minus 1 within
> a frame. When a full frame is transferred, the address increases
> by the ES plus the frame index (FI) value minus 1.
> 
> The omap-dma code didn't account for the 'minus 1' in the FI register.
> To get correct addressing, add 1 to the src_icg value.
> 
> This was found when testing a hacked version of the media m2m-deinterlace.c
> driver on a Pandaboard.
> 
> The only other source that uses this feature is omap_vout_vrfb.c,
> and that adds a + 1 when setting the dst_icg. This is a workaround
> for the broken omap-dma.c behavior. So remove the workaround at the
> same time that we fix omap-dma.c.
> 
> I tested the omap_vout driver with a Beagle XM board to check that
> the '+ 1' in omap_vout_vrfb.c was indeed a workaround for the omap-dma
> bug.
> 
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Regards,
Mauro

> ---
> Changes since v1: removed unnecessary parenthesis in omap_vout_vrfb.c
> as suggested by Laurent.
> 
> It makes sense that this patch goes in through the dmaengine subsystem
> (Mauro, can you Ack this patch?), but if preferred it can also go in
> through the media subsystem if we get an Ack from Vinod.
> ---
>  drivers/dma/ti/omap-dma.c                    | 4 ++--
>  drivers/media/platform/omap/omap_vout_vrfb.c | 3 +--
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/ti/omap-dma.c b/drivers/dma/ti/omap-dma.c
> index ba2489d4ea24..ba27802efcd0 100644
> --- a/drivers/dma/ti/omap-dma.c
> +++ b/drivers/dma/ti/omap-dma.c
> @@ -1234,7 +1234,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_dma_interleaved(
>  	if (src_icg) {
>  		d->ccr |= CCR_SRC_AMODE_DBLIDX;
>  		d->ei = 1;
> -		d->fi = src_icg;
> +		d->fi = src_icg + 1;
>  	} else if (xt->src_inc) {
>  		d->ccr |= CCR_SRC_AMODE_POSTINC;
>  		d->fi = 0;
> @@ -1249,7 +1249,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_dma_interleaved(
>  	if (dst_icg) {
>  		d->ccr |= CCR_DST_AMODE_DBLIDX;
>  		sg->ei = 1;
> -		sg->fi = dst_icg;
> +		sg->fi = dst_icg + 1;
>  	} else if (xt->dst_inc) {
>  		d->ccr |= CCR_DST_AMODE_POSTINC;
>  		sg->fi = 0;
> diff --git a/drivers/media/platform/omap/omap_vout_vrfb.c b/drivers/media/platform/omap/omap_vout_vrfb.c
> index 29e3f5da59c1..11ec048929e8 100644
> --- a/drivers/media/platform/omap/omap_vout_vrfb.c
> +++ b/drivers/media/platform/omap/omap_vout_vrfb.c
> @@ -253,8 +253,7 @@ int omap_vout_prepare_vrfb(struct omap_vout_device *vout,
>  	 */
> 
>  	pixsize = vout->bpp * vout->vrfb_bpp;
> -	dst_icg = ((MAX_PIXELS_PER_LINE * pixsize) -
> -		  (vout->pix.width * vout->bpp)) + 1;
> +	dst_icg = MAX_PIXELS_PER_LINE * pixsize - vout->pix.width * vout->bpp;
> 
>  	xt->src_start = vout->buf_phy_addr[vb->i];
>  	xt->dst_start = vout->vrfb_context[vb->i].paddr[0];