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

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

Hans,

On 30/07/2019 9.14, Hans Verkuil wrote:
> 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.

Thanks for catching it. I have implemented the interleaved support based
on the omap_vout_vrfb driver's behavior and hence I have missed the + 1
in the omap-dma.

Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

> 
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> ---
> 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.
> 
> Regards,
> 
> 	Hans
> ---
>  drivers/dma/ti/omap-dma.c                    | 4 ++--
>  drivers/media/platform/omap/omap_vout_vrfb.c | 2 +-
>  2 files changed, 3 insertions(+), 3 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..729b1bf9395f 100644
> --- a/drivers/media/platform/omap/omap_vout_vrfb.c
> +++ b/drivers/media/platform/omap/omap_vout_vrfb.c
> @@ -254,7 +254,7 @@ 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;
> +		  (vout->pix.width * vout->bpp));
> 
>  	xt->src_start = vout->buf_phy_addr[vb->i];
>  	xt->dst_start = vout->vrfb_context[vb->i].paddr[0];
> 

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