Hi Laurent,
On Sat, Aug 15, 2015 at 1:42 AM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> From 131968befd5de3400631b879b1574beea27b8239 Mon Sep 17 00:00:00 2001
> From: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> Date: Sat, 15 Aug 2015 01:28:28 +0300
> Subject: [PATCH] dmaengine: rcar-dmac: Fix residue reporting for pending
> descriptors
>
> 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.
Thanks!
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> ---
> drivers/dma/sh/rcar-dmac.c | 28 ++++++++++++++++++++++++++--
> 1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 7820d07e7bee..a98596a1f12f 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1143,19 +1143,43 @@ 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;
>
> +
> + /*
> + * 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;
> + }
The descriptor may be either on the pending or active list, so I had to add
+ list_for_each_entry(desc, &chan->desc.active, node) {
+ if (cookie == desc->async_tx.cookie)
+ return desc->size;
+ }
After that it seems to work fine. Will do more testing...
> +
> + /*
> + * 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;
> + }
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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