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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Wed, 10 May 2023 15:46:58 -0700
Message-ID: <CAE-0n532y=ARQ_+urEA_b3zUn+gKTu1fgK_siHNt3CpbLB9PZg@mail.gmail.com>
Subject: Re: [PATCH v1 2/2] drm/msm/dp: add mutex to protect internal_hpd
 against race condition between different threads
To:     Kuogee Hsieh <quic_khsieh@quicinc.com>, agross@kernel.org,
        airlied@gmail.com, andersson@kernel.org, daniel@ffwll.ch,
        dianders@chromium.org, dmitry.baryshkov@linaro.org,
        dri-devel@lists.freedesktop.org, robdclark@gmail.com,
        sean@poorly.run, vkoul@kernel.org
Cc:     quic_abhinavk@quicinc.com, quic_jesszhan@quicinc.com,
        quic_sbillaka@quicinc.com, marijn.suijten@somainline.org,
        freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Quoting Kuogee Hsieh (2023-05-10 13:31:05)
> Intrenal_hpd is referenced by event thread but set by drm bridge callback
> context. Add mutex to protect internal_hpd to avoid conflicts between
> threads.
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---

This patch looks completely unnecessary. How can dp_bridge_hpd_enable()
be called at the same time that dp_bridge_hpd_disable() is called or
dp_bridge_hpd_notify() is called? Isn't there locking or ordering at a
higher layer?