Re: [PATCH] [BUGREPORT] media: v4l: omap_vout: vrfb: initialize DMA flags

From: Peter Ujfalusi
Date: Mon Jul 17 2017 - 06:22:46 EST


Arnd,

sorry for the delayed response, I was away w/o internet connection for
the past weeks.

On 2017-07-10 14:18, Arnd Bergmann wrote:
> Passing uninitialized flags into device_prep_interleaved_dma is clearly
> a bad idea, and we get a compiler warning for it:
>
> drivers/media/platform/omap/omap_vout_vrfb.c: In function 'omap_vout_prepare_vrfb':
> drivers/media/platform/omap/omap_vout_vrfb.c:273:5: error: 'flags' may be used uninitialized in this function [-Werror=maybe-uninitialized]

I can not explain why I have missed this.

> It seems that the OMAP dmaengine ignores the flags, but we should
> pick the right ones anyway. Unfortunately I don't know what they
> should be, so I just picked the most common flags. Please set the
> right flags here and fold the modified patch.

The flags are fine.

>
> Fixes: 6a1560ecaa8c ("media: v4l: omap_vout: vrfb: Convert to dmaengine")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

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

> ---
> drivers/media/platform/omap/omap_vout_vrfb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/omap/omap_vout_vrfb.c b/drivers/media/platform/omap/omap_vout_vrfb.c
> index 45a553d4f5b2..fed28b6bbbc0 100644
> --- a/drivers/media/platform/omap/omap_vout_vrfb.c
> +++ b/drivers/media/platform/omap/omap_vout_vrfb.c
> @@ -233,7 +233,7 @@ int omap_vout_prepare_vrfb(struct omap_vout_device *vout,
> struct videobuf_buffer *vb)
> {
> struct dma_async_tx_descriptor *tx;
> - enum dma_ctrl_flags flags;
> + enum dma_ctrl_flags flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
> struct dma_chan *chan = vout->vrfb_dma_tx.chan;
> struct dma_device *dmadev = chan->device;
> struct dma_interleaved_template *xt = vout->vrfb_dma_tx.xt;
>

- Péter