On 2021-04-13 20:17, Stephen Boyd wrote:

Quoting Kuogee Hsieh (2021-04-13 16:11:30)

...

At dongle unplug, dp initializes audio_comp followed by sending disconnect event notification to audio and to make sure audio had shutdown completely by wait for audio completion notification at display_disable(). This patch

Is this dp_display_disable()? Doubtful that display_disable() is the function we're talking about.

yes

...

will not re initialize audio_comp at display_disable() if audio shutdown is triggered by dongle unplugged.

This commit text seems to say the why before the what, where why is "dp initializes audio_comp followed by sending disconnect.." and the what is "this patch will no re-initialized audio_comp...". Can you reorder this so the what comes before the why?

ok

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Signed-off-by: Kuogee Hsieh khsieh@codeaurora.org

drivers/gpu/drm/msm/dp/dp_display.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 0ba71c7..1d71c95 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -894,8 +894,10 @@ static int dp_display_disable(struct dp_display_private *dp, u32 data) /* wait only if audio was enabled */ if (dp_display->audio_enabled) { /* signal the disconnect event */

•           reinit_completion(&dp->audio_comp);
  

•           dp_display_handle_plugged_change(dp_display, false);
  

•           if (dp->hpd_state != ST_DISCONNECT_PENDING) {
  

•                   reinit_completion(&dp->audio_comp);
  

Why is this reinitialized here at all? Wouldn't it make more sense to initialize the completion once at cable plug in and then not initialize the completion anywhere else? Or initialize the completion whenever dp_display->audio_enabled is set to true and then only wait for the completion here if that boolean is true? Or initialize the completion when dp_display_handle_plugged_change() is passed true for the 'plugged' argument? yes, i think it is better approach, this will take care of both unplug and suspend.

I started reading the code and quickly got lost figuring out how dp_display_handle_plugged_change() worked and the interaction between the dp display code and the audio codec embedded in here. There seem to be a couple of conditions that cut off things early, like dp_display->audio_enabled and audio->engine_on. Why? Why does dp_display_signal_audio_complete() call complete_all() vs. just complete()? Please help! :(

...

•                   dp_display_handle_plugged_change(dp_display, 
  

false);

I think it's this way because dp_hpd_unplug_handle() is the function that sets the hpd_state to ST_DISCONNECT_PENDING and then reinitializes the completion (why?) and calls dp_display_handle_plugged_change(). So the commit text could say that reinitializing the completion again here at dp_display_disable() is racing with the audio code in the case that dp_hpd_unplug_handle() already called dp_display_handle_plugged_change() and it would make more sense. But the question still stands why that race even exists in the first place vs. initializing the completion variable in only one place unconditionally when the cable is connected, in dp_hpd_plug_handle() or dp_display_post_enable().

...

•           }
            if (!wait_for_completion_timeout(&dp->audio_comp,
                            HZ * 5))
                    DRM_ERROR("audio comp timeout\n");