linux-kernel - Re: [PATCH v5] drm/msm/dp: power off DP phy at suspend

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Date:   Thu, 03 Jun 2021 14:59:49 -0700
From:   khsieh@...eaurora.org
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org, robdclark@...il.com,
        sean@...rly.run, vkoul@...nel.org, abhinavk@...eaurora.org,
        aravindh@...eaurora.org, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] drm/msm/dp: power off DP phy at suspend

On 2021-06-03 13:22, Stephen Boyd wrote:
> Can you Cc dri-devel?
> 
Sorry for dropping this cc.
Should I re submit this v5 with cc=dri-devel?



> Quoting Kuogee Hsieh (2021-06-03 08:40:46)
>> 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.
>>