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

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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



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