From: Radhey Shyam Pandey <radheys@xilinx.com>
To: Vinod Koul <vkoul@kernel.org>
Cc: "dan.j.williams@intel.com" <dan.j.williams@intel.com>,
Michal Simek <michals@xilinx.com>,
"nick.graumann@gmail.com" <nick.graumann@gmail.com>,
"andrea.merello@gmail.com" <andrea.merello@gmail.com>,
Appana Durga Kedareswara Rao <appanad@xilinx.com>,
"mcgrof@kernel.org" <mcgrof@kernel.org>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
git <git@xilinx.com>
Subject: RE: [PATCH] dmaengine: xilinx_dma: Reset DMA channel in dma_terminate_all
Date: Wed, 11 Dec 2019 14:46:06 +0000 [thread overview]
Message-ID: <CH2PR02MB70009D78EA8C487BFFA54964C75A0@CH2PR02MB7000.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20191210060113.GP82508@vkoul-mobl>
> -----Original Message-----
> From: Vinod Koul <vkoul@kernel.org>
> Sent: Tuesday, December 10, 2019 11:31 AM
> To: Radhey Shyam Pandey <radheys@xilinx.com>
> Cc: dan.j.williams@intel.com; Michal Simek <michals@xilinx.com>;
> nick.graumann@gmail.com; andrea.merello@gmail.com; Appana Durga
> Kedareswara Rao <appanad@xilinx.com>; mcgrof@kernel.org;
> dmaengine@vger.kernel.org; linux-kernel@vger.kernel.org; git
> <git@xilinx.com>
> Subject: Re: [PATCH] dmaengine: xilinx_dma: Reset DMA channel in
> dma_terminate_all
>
> On 25-11-19, 12:12, Radhey Shyam Pandey wrote:
> > Reset DMA channel after stop to ensure that pending transfers and
> > FIFOs in the datapath are flushed or completed. It fixes intermittent
> > data verification failure reported by xilinx dma test client.
> >
> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
> > ---
> > drivers/dma/xilinx/xilinx_dma.c | 17 +++++++++--------
> > 1 file changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/dma/xilinx/xilinx_dma.c
> > b/drivers/dma/xilinx/xilinx_dma.c index a9c5d5c..6f1539c 100644
> > --- a/drivers/dma/xilinx/xilinx_dma.c
> > +++ b/drivers/dma/xilinx/xilinx_dma.c
> > @@ -2404,16 +2404,17 @@ static int xilinx_dma_terminate_all(struct
> dma_chan *dchan)
> > u32 reg;
> > int err;
> >
> > - if (chan->cyclic)
> > - xilinx_dma_chan_reset(chan);
>
> So reset is required for non cyclic cases as well now?
Yes. In absence of reset in non-cyclic case, when dmatest client
driver is stressed and loaded/unloaded multiple times we see dma
data comparison failures. Possibly IP is prefetching/holding the
previous state and reset ensures a clean state on each iteration.
>
> > -
> > - err = chan->stop_transfer(chan);
> > - if (err) {
> > - dev_err(chan->dev, "Cannot stop channel %p: %x\n",
> > - chan, dma_ctrl_read(chan,
> XILINX_DMA_REG_DMASR));
> > - chan->err = true;
> > + if (!chan->cyclic) {
> > + err = chan->stop_transfer(chan);
>
> no stop for cyclic now..?
After reset stop is not needed, so for the cyclic mode we only do reset.
>
> > + if (err) {
> > + dev_err(chan->dev, "Cannot stop channel %p: %x\n",
> > + chan, dma_ctrl_read(chan,
> > + XILINX_DMA_REG_DMASR));
> > + chan->err = true;
> > + }
> > }
> >
> > + xilinx_dma_chan_reset(chan);
> > /* Remove and free all of the descriptors in the lists */
> > xilinx_dma_free_descriptors(chan);
> > chan->idle = true;
> > --
> > 2.7.4
>
> --
> ~Vinod
next prev parent reply other threads:[~2019-12-11 14:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 6:42 [PATCH] dmaengine: xilinx_dma: Reset DMA channel in dma_terminate_all Radhey Shyam Pandey
2019-12-10 6:01 ` Vinod Koul
2019-12-11 14:46 ` Radhey Shyam Pandey [this message]
2019-12-18 6:04 ` Vinod Koul
2019-12-18 13:22 ` Radhey Shyam Pandey
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CH2PR02MB70009D78EA8C487BFFA54964C75A0@CH2PR02MB7000.namprd02.prod.outlook.com \
--to=radheys@xilinx.com \
--cc=andrea.merello@gmail.com \
--cc=appanad@xilinx.com \
--cc=dan.j.williams@intel.com \
--cc=dmaengine@vger.kernel.org \
--cc=git@xilinx.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mcgrof@kernel.org \
--cc=michals@xilinx.com \
--cc=nick.graumann@gmail.com \
--cc=vkoul@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).