linux-kernel - [PATCH v4 2/2] drm/bridge: analogix

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Date:   Tue,  1 Mar 2022 18:11:39 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Jonas Karlman <jonas@...boo.se>, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Sean Paul <sean@...rly.run>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Doug Anderson <dianders@...omium.org>,
        linux-rockchip@...ts.infradead.org,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Brian Norris <briannorris@...omium.org>
Subject: [PATCH v4 2/2] drm/bridge: analogix_dp: Enable autosuspend

DP AUX transactions can consist of many short operations. There's no
need to power things up/down in short intervals.

I pick an arbitrary 100ms; for the systems I'm testing (Rockchip
RK3399), runtime-PM transitions only take a few microseconds.

Signed-off-by: Brian Norris <briannorris@...omium.org>
---

Changes in v4:
 - call pm_runtime_mark_last_busy() and
   pm_runtime_dont_use_autosuspend()
 - drop excess pm references around drm_get_edid(), now that we grab and
   hold in the dp-aux helper

Changes in v3:
 - New in v3

 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 16be279aed2c..b248d352f2bd 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1119,9 +1119,7 @@ static int analogix_dp_get_modes(struct drm_connector *connector)
 			return 0;
 		}
 
-		pm_runtime_get_sync(dp->dev);
 		edid = drm_get_edid(connector, &dp->aux.ddc);
-		pm_runtime_put(dp->dev);
 		if (edid) {
 			drm_connector_update_edid_property(&dp->connector,
 							   edid);
@@ -1642,7 +1640,8 @@ static ssize_t analogix_dpaux_transfer(struct drm_dp_aux *aux,
 
 	ret = analogix_dp_transfer(dp, msg);
 out:
-	pm_runtime_put(dp->dev);
+	pm_runtime_mark_last_busy(dp->dev);
+	pm_runtime_put_autosuspend(dp->dev);
 
 	return ret;
 }
@@ -1775,6 +1774,8 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
 	if (ret)
 		return ret;
 
+	pm_runtime_use_autosuspend(dp->dev);
+	pm_runtime_set_autosuspend_delay(dp->dev, 100);
 	pm_runtime_enable(dp->dev);
 
 	ret = analogix_dp_create_bridge(drm_dev, dp);
@@ -1786,6 +1787,7 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
 	return 0;
 
 err_disable_pm_runtime:
+	pm_runtime_dont_use_autosuspend(dp->dev);
 	pm_runtime_disable(dp->dev);
 	drm_dp_aux_unregister(&dp->aux);
 
@@ -1804,6 +1806,7 @@ void analogix_dp_unbind(struct analogix_dp_device *dp)
 	}
 
 	drm_dp_aux_unregister(&dp->aux);
+	pm_runtime_dont_use_autosuspend(dp->dev);
 	pm_runtime_disable(dp->dev);
 }
 EXPORT_SYMBOL_GPL(analogix_dp_unbind);
-- 
2.35.1.574.g5d30c73bfb-goog