[PATCH v2 1/2] drm/bridge: it6505: Adapt runtime power management framework

[Pin-yen Lin]

Use pm_runtime_(get|put)_sync to control the bridge power, and add
SET_SYSTEM_SLEEP_PM_OPS with pm_runtime_force_(suspend|resume) to it6505
driver. Without SET_SYSTEM_SLEEP_PM_OPS, the bridge will be powered on
unnecessarily when no external display is connected.

Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
Signed-off-by: Pin-yen Lin <treapk...@chromium.org>

---

Changes in v2:
- Handle the error from pm_runtime_get_sync in it6505_extcon_work

 drivers/gpu/drm/bridge/ite-it6505.c | 33 +++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c 
b/drivers/gpu/drm/bridge/ite-it6505.c
index 2bb957cffd94..685d8e750b12 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -421,6 +421,7 @@ struct it6505 {
        struct notifier_block event_nb;
        struct extcon_dev *extcon;
        struct work_struct extcon_wq;
+       int extcon_state;
        enum drm_connector_status connector_status;
        enum link_train_status link_state;
        struct work_struct link_works;
@@ -2685,31 +2686,42 @@ static void it6505_extcon_work(struct work_struct *work)
 {
        struct it6505 *it6505 = container_of(work, struct it6505, extcon_wq);
        struct device *dev = &it6505->client->dev;
-       int state = extcon_get_state(it6505->extcon, EXTCON_DISP_DP);
-       unsigned int pwroffretry = 0;
+       int state, ret;
 
        if (it6505->enable_drv_hold)
                return;
 
        mutex_lock(&it6505->extcon_lock);
 
+       state = extcon_get_state(it6505->extcon, EXTCON_DISP_DP);
        DRM_DEV_DEBUG_DRIVER(dev, "EXTCON_DISP_DP = 0x%02x", state);
+
+       if (state == it6505->extcon_state)
+               goto unlock;
+
        if (state > 0) {
                DRM_DEV_DEBUG_DRIVER(dev, "start to power on");
                msleep(100);
-               it6505_poweron(it6505);
+               ret = pm_runtime_get_sync(dev);
+
+               /*
+                * On system resume, extcon_work can be triggered before
+                * pm_runtime_force_resume re-enables runtime power management.
+                * Handling the error here to make sure the bridge is powered 
on.
+                */
+               if (ret)
+                       it6505_poweron(it6505);
        } else {
                DRM_DEV_DEBUG_DRIVER(dev, "start to power off");
-               while (it6505_poweroff(it6505) && pwroffretry++ < 5) {
-                       DRM_DEV_DEBUG_DRIVER(dev, "power off fail %d times",
-                                            pwroffretry);
-               }
+               pm_runtime_put_sync(dev);
 
                drm_helper_hpd_irq_event(it6505->bridge.dev);
                memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
                DRM_DEV_DEBUG_DRIVER(dev, "power off it6505 success!");
        }
+       it6505->extcon_state = state;
 
+unlock:
        mutex_unlock(&it6505->extcon_lock);
 }
 
@@ -3032,8 +3044,10 @@ static __maybe_unused int it6505_bridge_suspend(struct 
device *dev)
        return it6505_poweroff(it6505);
 }
 
-static SIMPLE_DEV_PM_OPS(it6505_bridge_pm_ops, it6505_bridge_suspend,
-                        it6505_bridge_resume);
+static const struct dev_pm_ops it6505_bridge_pm_ops = {
+       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, 
pm_runtime_force_resume)
+       SET_RUNTIME_PM_OPS(it6505_bridge_suspend, it6505_bridge_resume, NULL)
+};
 
 static int it6505_init_pdata(struct it6505 *it6505)
 {
@@ -3315,6 +3329,7 @@ static int it6505_i2c_probe(struct i2c_client *client,
 
        DRM_DEV_DEBUG_DRIVER(dev, "it6505 device name: %s", dev_name(dev));
        debugfs_init(it6505);
+       pm_runtime_enable(dev);
 
        it6505->bridge.funcs = &it6505_bridge_funcs;
        it6505->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
-- 
2.38.0.rc1.362.ged0d419d3c-goog