From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Mon, 17 Aug 2015 14:03:52 +0000 Subject: Re: Issues with rcar-dmac and sh-sci Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org Hi Laurent, On Sat, Aug 15, 2015 at 1:42 AM, Laurent Pinchart wrote: > From 131968befd5de3400631b879b1574beea27b8239 Mon Sep 17 00:00:00 2001 > From: Laurent Pinchart > 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 > Signed-off-by: Laurent Pinchart > --- > 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@linux-m68k.org 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