dmaengine Archive on lore.kernel.org
 help / color / Atom feed
From: Robin Gong <yibin.gong@nxp.com>
To: Philipp Puschmann <philipp.puschmann@emlix.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "jlu@pengutronix.de" <jlu@pengutronix.de>,
	Andy Duan <fugang.duan@nxp.com>,
	"l.stach@pengutronix.de" <l.stach@pengutronix.de>,
	"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"festevam@gmail.com" <festevam@gmail.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v5 1/3] dmaengine: imx-sdma: fix buffer ownership
Date: Wed, 4 Dec 2019 09:19:59 +0000
Message-ID: <VE1PR04MB6638A9E882D40FB7F8CB7F14895D0@VE1PR04MB6638.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20190923135808.815-2-philipp.puschmann@emlix.com>

On 2019-9-23 Philipp Puschmann <philipp.puschmann@emlix.com> wrote:
> BD_DONE flag marks ownership of the buffer. When 1 SDMA owns the buffer,
> when 0 ARM owns it. When processing the buffers in
> sdma_update_channel_loop the ownership of the currently processed buffer
> was set to SDMA again before running the callback function of the buffer and
> while the sdma script may be running in parallel. So there was the possibility to
> get the buffer overwritten by SDMA before it has been processed by kernel
Does this patch need indeed? I don't think any difference here move done flag
before callback or after callback, because callback never care this flag and actually
done flag is setup for next time rather than this time. Basically, this flag should be
set to 1 quickly asap so that sdma could use this bd asap. If delay the flag may cause
sdma channel stop since all BDs consumed. Could you try again your case without
this patch?
> leading to kind of random errors in the upper layers, e.g. bluetooth.
> 
> Fixes: 1ec1e82f2510 ("dmaengine: Add Freescale i.MX SDMA support")
> Signed-off-by: Philipp Puschmann <philipp.puschmann@emlix.com>
> ---
> 
> Changelog v5:
>  - no changes
> 
> Changelog v4:
>  - fixed the fixes tag
> 
> Changelog v3:
>  - use correct dma_wmb() instead of dma_wb()
>  - add fixes tag
> 
> Changelog v2:
>  - add dma_wb()
> 
>  drivers/dma/imx-sdma.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index
> 9ba74ab7e912..b42281604e54 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -802,7 +802,6 @@ static void sdma_update_channel_loop(struct
> sdma_channel *sdmac)
>  		*/
> 
>  		desc->chn_real_count = bd->mode.count;
> -		bd->mode.status |= BD_DONE;
>  		bd->mode.count = desc->period_len;
>  		desc->buf_ptail = desc->buf_tail;
>  		desc->buf_tail = (desc->buf_tail + 1) % desc->num_bd; @@ -817,6
> +816,9 @@ static void sdma_update_channel_loop(struct sdma_channel
> *sdmac)
>  		dmaengine_desc_get_callback_invoke(&desc->vd.tx, NULL);
>  		spin_lock(&sdmac->vc.lock);
> 
> +		dma_wmb();
> +		bd->mode.status |= BD_DONE;
> +
>  		if (error)
>  			sdmac->status = old_status;
>  	}
> --
> 2.23.0


  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23 13:58 [PATCH v5 0/3] Fix UART DMA freezes for i.MX SOCs Philipp Puschmann
2019-09-23 13:58 ` [PATCH v5 1/3] dmaengine: imx-sdma: fix buffer ownership Philipp Puschmann
2019-12-03  9:47   ` Lucas Stach
2019-12-04  9:19   ` Robin Gong [this message]
2019-09-23 13:58 ` [PATCH v5 2/3] dmaengine: imx-sdma: fix dma freezes Philipp Puschmann
2019-09-24  3:14   ` Robin Gong
2019-09-23 13:58 ` [PATCH v5 3/3] dmaengine: imx-sdma: drop redundant variable Philipp Puschmann
2019-09-23 14:55 ` [PATCH v5 0/3] Fix UART DMA freezes for i.MX SOCs Adam Ford
2019-09-23 15:06   ` Philipp Puschmann
2019-09-23 15:09     ` Jan Lübbe

Reply instructions:

You may reply publically 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=VE1PR04MB6638A9E882D40FB7F8CB7F14895D0@VE1PR04MB6638.eurprd04.prod.outlook.com \
    --to=yibin.gong@nxp.com \
    --cc=dan.j.williams@intel.com \
    --cc=dmaengine@vger.kernel.org \
    --cc=festevam@gmail.com \
    --cc=fugang.duan@nxp.com \
    --cc=jlu@pengutronix.de \
    --cc=kernel@pengutronix.de \
    --cc=l.stach@pengutronix.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=philipp.puschmann@emlix.com \
    --cc=s.hauer@pengutronix.de \
    --cc=shawnguo@kernel.org \
    --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

dmaengine Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dmaengine/0 dmaengine/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dmaengine dmaengine/ https://lore.kernel.org/dmaengine \
		dmaengine@vger.kernel.org
	public-inbox-index dmaengine

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.dmaengine


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git