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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Wed, 2 Jun 2021 17:23:04 -0700
Message-ID: <CAE-0n522L0hmAK40xj3TGimBjeqQgqO2YWsGOrYv-BPqr33tkA@mail.gmail.com>
Subject: Re: [PATCH v4] drm/msm/dp: power off DP phy at suspend
To:     Kuogee Hsieh <khsieh@codeaurora.org>, agross@kernel.org,
        bjorn.andersson@linaro.org, robdclark@gmail.com, sean@poorly.run,
        vkoul@kernel.org
Cc:     abhinavk@codeaurora.org, aravindh@codeaurora.org,
        freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Quoting Kuogee Hsieh (2021-06-02 09:43:05)
> Normal DP suspend operation contains two steps, display off followed
> by dp suspend, to complete system wide suspending cycle if display is
> up at that time. In this case, DP phy will be powered off at display
> off. However there is an exception case that depending on the timing
> of dongle plug in during system wide suspending, sometimes display off
> procedure may be skipped and dp suspend was called directly. In this
> case, dp phy is stay at powered on (phy->power_count = 1) so that at
> next resume dp driver crash at main link clock enable due to phy is
> not physically powered on. This patch will call dp_ctrl_off_link_stream()
> to tear down main link and power off phy at dp_pm_suspend() if main link
> had been brought up.
>
> Changes in V2:
> -- stashed changes into dp_ctrl.c
> -- add is_phy_on to monitor phy state
>
> Changes in V3:
> -- delete is_phy_on
> -- call dp_ctrl_off_link_stream() from dp_pm_suspend()
>
> Changes in V4:
> -- delete changes made at dp_power.c
> -- move main link status checking to dp_pm_suspend
>
> Fixes: 0114f31a2903 ("drm/msm/dp: handle irq_hpd with sink_count = 0 correctly)
> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> ---

Ok, this seems to work and is nice and small

Tested-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>