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Subject: Re: [PATCH 0/3] i2c: i2c-qcom-geni: More properly fix the DMA race
To:     Douglas Anderson <dianders@chromium.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Wolfram Sang <wsa@kernel.org>,
        Akash Asthana <akashast@codeaurora.org>
Cc:     linux-arm-msm@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
        linux-i2c@vger.kernel.org, Andy Gross <agross@kernel.org>,
        Girish Mahadevan <girishm@codeaurora.org>,
        Karthikeyan Ramasubramanian <kramasub@codeaurora.org>,
        Mukesh Kumar Savaliya <msavaliy@codeaurora.org>,
        linux-kernel@vger.kernel.org
References: <20201008225235.2035820-1-dianders@chromium.org>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Message-ID: <4dcdc8b3-94aa-8e68-934d-70542897db6a@linaro.org>
Date:   Sat, 10 Oct 2020 16:16:48 +0300
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On 09/10/2020 01:52, Douglas Anderson wrote:
> Previously I landed commit 02b9aec59243 ("i2c: i2c-qcom-geni: Fix DMA
> transfer race") to fix a race we were seeing.  While that most
> definitely fixed the race we were seeing, it looks like it causes
> problems in the TX path, which we didn't stress test until we started
> trying to update firmware on devices.
> 
> Let's revert that patch and try another way: fix the original problem
> by disabling the interrupts that aren't relevant to DMA transfers.
> Now we can stress both TX and RX cases and see no problems.  I also
> can't find any place to put an msleep() that causes problems anymore.
> 
> Since this problem only affects i2c, I'm hoping for an Ack from Bjorn
> and then all these patches can go through the i2c tree.  However, if
> maintainers want to work a different way out to land that's OK too.

These patches fix I2C DMA issues on SM8250 we were observing
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


-- 
With best wishes
Dmitry