Re: [PATCH 4/4] dmaengine: rcar-dmac: Fix residue reporting for pending descriptors

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Niklas,

Thank you for the patch.

On Wednesday 15 Jun 2016 13:13:08 Niklas S�derlund wrote:
> From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> 
> Cookies corresponding to pending transfers have a residue value equal to
> the full size of the corresponding descriptor. The driver miscomputes
> that and uses the size of the active descriptor instead. Fix it.
> 
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> [geert: Also check desc.active list]
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Niklas S�derlund <niklas.soderlund+renesas@ragnatech.se>
> ---
>  drivers/dma/sh/rcar-dmac.c | 32 ++++++++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 59951fb..86aef28 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1145,19 +1145,47 @@ static unsigned int
> rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, struct
> rcar_dmac_desc *desc = chan->desc.running;
>  	struct rcar_dmac_xfer_chunk *running = NULL;
>  	struct rcar_dmac_xfer_chunk *chunk;
> +	enum dma_status status;
>  	unsigned int residue = 0;
>  	unsigned int dptr = 0;
> 
>  	if (!desc)
>  		return 0;
> 
> +

One blank line is enough.

Apart from that your change to my patch looks good, thank you for fixing it.

> +	/*
> +	 * If the cookie corresponds to a descriptor that has been completed
> +	 * there is no residue. The same check has already been performed by the
> +	 * caller but without holding the channel lock, so the descriptor could
> +	 * now be complete.
> +	 */
> +	status = dma_cookie_status(&chan->chan, cookie, NULL);
> +	if (status == DMA_COMPLETE)
> +		return 0;
> +
>  	/*
>  	 * If the cookie doesn't correspond to the currently running transfer
>  	 * then the descriptor hasn't been processed yet, and the residue is
>  	 * equal to the full descriptor size.
>  	 */
> -	if (cookie != desc->async_tx.cookie)
> -		return desc->size;
> +	if (cookie != desc->async_tx.cookie) {
> +		list_for_each_entry(desc, &chan->desc.pending, node) {
> +			if (cookie == desc->async_tx.cookie)
> +				return desc->size;
> +		}
> +		list_for_each_entry(desc, &chan->desc.active, node) {
> +			if (cookie == desc->async_tx.cookie)
> +				return desc->size;
> +		}
> +
> +		/*
> +		 * No descriptor found for the cookie, there's thus no residue.
> +		 * This shouldn't happen if the calling driver passes a correct
> +		 * cookie value.
> +		 */
> +		WARN(1, "No descriptor for cookie!");
> +		return 0;
> +	}
> 
>  	/*
>  	 * In descriptor mode the descriptor running pointer is not maintained

-- 
Regards,

Laurent Pinchart