linux-kernel - Re: [PATCH] remoteproc/mtk_scp: Move clk ops outside send

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Message-ID: <CAGXv+5FSc4H5QtMTZP7jj+SjDcU2u024cPm9LEAdT3oUoBusNg@mail.gmail.com>
Date:   Thu, 5 Jan 2023 17:03:21 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Tinghan Shen <tinghan.shen@...iatek.com>,
        Tzung-Bi Shih <tzungbi@...nel.org>,
        Allen-KH Cheng <allen-kh.cheng@...iatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] remoteproc/mtk_scp: Move clk ops outside send_lock

On Wed, Jan 4, 2023 at 4:31 PM Chen-Yu Tsai <wenst@...omium.org> wrote:
>
> Clocks are properly reference counted and do not need to be inside the
> lock range.
>
> Right now this triggers a false-positive lockdep warning on MT8192 based
> Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
> sub-device, the (actual) cros-ec I2C adapter registration, I2C client
> (not on cros-ec) probe doing i2c transfers and enabling clocks.
>
> This is a false positive because the cros-ec-rpmsg under mtk-scp does
> not have an I2C adapter, and also each I2C adapter and cros-ec instance
> have their own mutex.
>
> Move the clk operations outside of the send_lock range.

Well this managed to untangle the lockdep warning a bit, but it still
appears. I'll keep looking into it.