linux-kernel - Re: [PATCH 0/3] i2c: i2c-qcom-geni: More properly fix the DMA race

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Date:   Sat, 10 Oct 2020 16:16:48 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Wolfram Sang <wsa@...nel.org>,
        Akash Asthana <akashast@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        linux-i2c@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Girish Mahadevan <girishm@...eaurora.org>,
        Karthikeyan Ramasubramanian <kramasub@...eaurora.org>,
        Mukesh Kumar Savaliya <msavaliy@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] i2c: i2c-qcom-geni: More properly fix the DMA race

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@...aro.org>


-- 
With best wishes
Dmitry