From: Richard Leitner <richard.leitner@skidata.com>
To: Martin Fuzzey <martin.fuzzey@flowbird.group>
Cc: <dmaengine@vger.kernel.org>, <stable@vger.kernel.org>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
NXP Linux Team <linux-imx@nxp.com>,
Robin Gong <yibin.gong@nxp.com>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dmaengine: imx-sdma: fix context cache
Date: Fri, 28 Feb 2020 13:44:48 +0100 [thread overview]
Message-ID: <20200228124448.GA1689606@pcleri> (raw)
In-Reply-To: <1580305274-27274-1-git-send-email-martin.fuzzey@flowbird.group>
Hi,
On Wed, Jan 29, 2020 at 02:40:06PM +0100, Martin Fuzzey wrote:
> There is a DMA problem with the serial ports on i.MX6.
>
> When the following sequence is performed:
>
> 1) Open a port
> 2) Write some data
> 3) Close the port
> 4) Open a *different* port
> 5) Write some data
> 6) Close the port
>
> The second write sends nothing and the second close hangs.
> If the first close() is omitted it works.
>
> Adding logs to the the UART driver shows that the DMA is being setup but
> the callback is never invoked for the second write.
>
> This used to work in 4.19.
>
> Git bisect leads to:
> ad0d92d: "dmaengine: imx-sdma: refine to load context only once"
>
> This commit adds a "context_loaded" flag used to avoid unnecessary context
> setups.
> However the flag is only reset in sdma_channel_terminate_work(),
> which is only invoked in a worker triggered by sdma_terminate_all() IF
> there is an active descriptor.
>
> So, if no active descriptor remains when the channel is terminated, the
> flag is not reset and, when the channel is later reused the old context
> is used.
>
> Fix the problem by always resetting the flag in sdma_free_chan_resources().
>
> Fixes: ad0d92d: "dmaengine: imx-sdma: refine to load context only once"
> Cc: stable@vger.kernel.org
> Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
>
Thanks for the patch!
We were chasing this issue for days and just found your patch as we were
preparing our (quite similar) solution for submission ;-)
I've successfully tested your patch on a custom i.MX6Solo board.
Therefore feel free to add
Tested-by: Richard Leitner <richard.leitner@skidata.com>
regards;rl
next prev parent reply other threads:[~2020-02-28 12:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 13:40 [PATCH] dmaengine: imx-sdma: fix context cache Martin Fuzzey
2020-01-29 20:19 ` Fabio Estevam
2020-02-24 16:57 ` Vinod Koul
2020-02-28 12:44 ` Richard Leitner [this message]
2020-03-02 7:36 ` Robin Gong
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