Re: [PATCH v4 7/8] drm/msm/dp: add pm_runtime_force_suspend()/resume()

[Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>]

On 9/27/2023 3:00 PM, Dmitry Baryshkov wrote:
> On Wed, 27 Sept 2023 at 23:54, Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx> wrote:
> > After incorporated pm_runtime framework into eDP/DP driver, the
> incorporating
>
>
> > original dp_pm_suspend() to handle power off both DP phy and
> > controller during suspend and dp_pm_resume() to handle power on
> > both DP phy and controller during resume are not necessary since
> > those function are replaced by dp_pm_runtime_suspend() and
> > dp_pm_runtime_resume() through pm runtime framework.
> > Therefore add pm framework provides functions,
> > pm_runtime_force_suspend()/resume() to complete incorporating pm
> > runtime framework into DP driver.
> >
> > Changes in v4:
> > -- drop both dp_pm_prepare() and dp_pm_compete() from this change
> > -- delete ST_SUSPENDED state
> > -- rewording commit text to add more details regrading the purpose
> >     of this change
> >
> > Changes in v3:
> > -- replace dp_pm_suspend() with pm_runtime_force_suspend()
> > -- replace dp_pm_resume() with pm_runtime_force_resume()
> >
> > Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/dp/dp_display.c | 113 ++----------------------------------
> >   1 file changed, 5 insertions(+), 108 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> > index 9158a2c..711d262 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -49,7 +49,6 @@ enum {
> >          ST_CONNECTED,
> >          ST_DISCONNECT_PENDING,
> >          ST_DISPLAY_OFF,
> > -       ST_SUSPENDED,
> >   };
> >
> >   enum {
> > @@ -560,7 +559,7 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
> >          drm_dbg_dp(dp->drm_dev, "Before, type=%d hpd_state=%d\n",
> >                          dp->dp_display.connector_type, state);
> >
> > -       if (state == ST_DISPLAY_OFF || state == ST_SUSPENDED) {
> > +       if (state == ST_DISPLAY_OFF) {
> >                  mutex_unlock(&dp->event_mutex);
> >                  return 0;
> >          }
> > @@ -674,7 +673,7 @@ static int dp_irq_hpd_handle(struct dp_display_private *dp, u32 data)
> >          drm_dbg_dp(dp->drm_dev, "Before, type=%d hpd_state=%d\n",
> >                          dp->dp_display.connector_type, state);
> >
> > -       if (state == ST_DISPLAY_OFF || state == ST_SUSPENDED) {
> > +       if (state == ST_DISPLAY_OFF) {
> >                  mutex_unlock(&dp->event_mutex);
> >                  return 0;
> >          }
> > @@ -1321,110 +1320,10 @@ static int dp_pm_runtime_resume(struct device *dev)
> >          return 0;
> >   }
> >
> > -static int dp_pm_resume(struct device *dev)
> > -{
> > -       struct platform_device *pdev = to_platform_device(dev);
> > -       struct msm_dp *dp_display = platform_get_drvdata(pdev);
> > -       struct dp_display_private *dp;
> > -       int sink_count = 0;
> > -
> > -       dp = container_of(dp_display, struct dp_display_private, dp_display);
> > -
> > -       mutex_lock(&dp->event_mutex);
> > -
> > -       drm_dbg_dp(dp->drm_dev,
> > -               "Before, type=%d core_inited=%d phy_inited=%d power_on=%d\n",
> > -               dp->dp_display.connector_type, dp->core_initialized,
> > -               dp->phy_initialized, dp_display->power_on);
> > -
> > -       /* start from disconnected state */
> > -       dp->hpd_state = ST_DISCONNECTED;
> > -
> > -       /* turn on dp ctrl/phy */
> > -       dp_display_host_init(dp);
> > -
> > -       if (dp_display->is_edp)
> > -               dp_catalog_ctrl_hpd_enable(dp->catalog);
> > -
> > -       if (dp_catalog_link_is_connected(dp->catalog)) {
> > -               /*
> > -                * set sink to normal operation mode -- D0
> > -                * before dpcd read
> > -                */
> > -               dp_display_host_phy_init(dp);
> > -               dp_link_psm_config(dp->link, &dp->panel->link_info, false);
> > -               sink_count = drm_dp_read_sink_count(dp->aux);
> > -               if (sink_count < 0)
> > -                       sink_count = 0;
> > -
> > -               dp_display_host_phy_exit(dp);
> > -       }
> > -
> > -       dp->link->sink_count = sink_count;
> > -       /*
> > -        * can not declared display is connected unless
> > -        * HDMI cable is plugged in and sink_count of
> > -        * dongle become 1
> > -        * also only signal audio when disconnected
> > -        */
> > -       if (dp->link->sink_count) {
> > -               dp->dp_display.link_ready = true;
> > -       } else {
> > -               dp->dp_display.link_ready = false;
> > -               dp_display_handle_plugged_change(dp_display, false);
> > -       }
> > -
> > -       drm_dbg_dp(dp->drm_dev,
> > -               "After, type=%d sink=%d conn=%d core_init=%d phy_init=%d power=%d\n",
> > -               dp->dp_display.connector_type, dp->link->sink_count,
> > -               dp->dp_display.link_ready, dp->core_initialized,
> > -               dp->phy_initialized, dp_display->power_on);
> > -
> > -       mutex_unlock(&dp->event_mutex);
> > -
> > -       return 0;
> > -}
> > -
> > -static int dp_pm_suspend(struct device *dev)
> > -{
> > -       struct platform_device *pdev = to_platform_device(dev);
> > -       struct msm_dp *dp_display = platform_get_drvdata(pdev);
> > -       struct dp_display_private *dp;
> > -
> > -       dp = container_of(dp_display, struct dp_display_private, dp_display);
> > -
> > -       mutex_lock(&dp->event_mutex);
> > -
> > -       drm_dbg_dp(dp->drm_dev,
> > -               "Before, type=%d core_inited=%d  phy_inited=%d power_on=%d\n",
> > -               dp->dp_display.connector_type, dp->core_initialized,
> > -               dp->phy_initialized, dp_display->power_on);
> > -
> > -       /* mainlink enabled */
> > -       if (dp_power_clk_status(dp->power, DP_CTRL_PM))
> > -               dp_ctrl_off_link_stream(dp->ctrl);
> > -
> > -       dp_display_host_phy_exit(dp);
> I was under the impression that dp_pm_runtime_suspend / _resume
> functions perform phy init/exit only in eDP cases. Can we really drop
> the main suspend/resume functions?

yes on eDP case since it is embedded.

for external DP case, there are two steps

step 1: enable DP controller's  hpd block and start waiting for hpd 
interrupts at dp_display_hpd_enable()

step 2:  at plugin interrupts,  dp_display_host_phy_init()

step 3: at unplug interrupt: dp_bridge_atomic_post_disable() 
dp_display_host_phy_exi()

at runtime, there is loop between step 2 and step 3

step  4: disable DP controller's  hpd block

> > -
> > -       /* host_init will be called at pm_resume */
> > -       dp_display_host_deinit(dp);
> > -
> > -       dp->hpd_state = ST_SUSPENDED;
> > -
> > -       drm_dbg_dp(dp->drm_dev,
> > -               "After, type=%d core_inited=%d phy_inited=%d power_on=%d\n",
> > -               dp->dp_display.connector_type, dp->core_initialized,
> > -               dp->phy_initialized, dp_display->power_on);
> > -
> > -       mutex_unlock(&dp->event_mutex);
> > -
> > -       return 0;
> > -}
> > -
> >   static const struct dev_pm_ops dp_pm_ops = {
> >          SET_RUNTIME_PM_OPS(dp_pm_runtime_suspend, dp_pm_runtime_resume, NULL)
> > -       .suspend = dp_pm_suspend,
> > -       .resume =  dp_pm_resume,
> > +       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> > +                                pm_runtime_force_resume)
> >   };
> >
> >   static struct platform_driver dp_display_driver = {
> > @@ -1658,9 +1557,6 @@ void dp_bridge_atomic_post_disable(struct drm_bridge *drm_bridge,
> >
> >          dp_display = container_of(dp, struct dp_display_private, dp_display);
> >
> > -       if (dp->is_edp)
> > -               dp_hpd_unplug_handle(dp_display, 0);
> Why?

dp_hpd_unplug_handle() does not tear down phy.

Therefore eDP does not need to call unplug handle.



> > -
> >          mutex_lock(&dp_display->event_mutex);
> >
> >          state = dp_display->hpd_state;
> > @@ -1748,6 +1644,7 @@ void dp_bridge_hpd_disable(struct drm_bridge *bridge)
> >          dp_catalog_ctrl_hpd_disable(dp->catalog);
> >
> >          dp_display->internal_hpd = false;
> > +       dp->hpd_state = ST_DISCONNECTED;
> Why? We have only disabled sending of the HPD events. The dongle might
> still be connected.

dp_bridge_hpd_disable() disable dp controller hpd block (no more hpd 
interrupt will be received).

dp_bridge_hpd_disable() should happen after DP main link had been teared 
down already.

Therefore hpd_state need to be in default state so that next plugin 
handle will be start with correct state.


> >          pm_runtime_mark_last_busy(&dp->pdev->dev);
> >          pm_runtime_put_autosuspend(&dp->pdev->dev);
> > --
> > 2.7.4
>
> --
> With best wishes
>
> Dmitry