[PATCH 5/5] drm/bridge: ti-sn65dsi86: support booloader enabled display

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

Request the enable gpio ASIS to avoid disabling bridge during probe, if
already enabled.  And if already enabled, defer enabling runpm until
attach to avoid cutting off the power to the bridge.

Once we get to attach, we know panel and drm driver are probed
successfully, so at this point it i s safe to enable runpm and reset the
bridge.  If we do it earlier, we kill efifb (in the case that panel or
drm driver do not probe successfully, giving the user no way to see what
is going on.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 7a046bcdd81b..8bdc33576992 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -257,6 +257,12 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge)
 						   .node = NULL,
 						 };
 
+	if (gpiod_get_value(pdata->enable_gpio)) {
+		pm_runtime_enable(pdata->dev);
+		ti_sn_bridge_resume(pdata->dev);
+		ti_sn_bridge_suspend(pdata->dev);
+	}
+
 	ret = drm_connector_init(bridge->dev, &pdata->connector,
 				 &ti_sn_bridge_connector_funcs,
 				 DRM_MODE_CONNECTOR_eDP);
@@ -813,7 +819,7 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
 	dev_set_drvdata(&client->dev, pdata);
 
 	pdata->enable_gpio = devm_gpiod_get(pdata->dev, "enable",
-					    GPIOD_OUT_LOW);
+					    GPIOD_ASIS);
 	if (IS_ERR(pdata->enable_gpio)) {
 		DRM_ERROR("failed to get enable gpio from DT\n");
 		ret = PTR_ERR(pdata->enable_gpio);
@@ -843,7 +849,9 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
-	pm_runtime_enable(pdata->dev);
+	if (!gpiod_get_value(pdata->enable_gpio)) {
+		pm_runtime_enable(pdata->dev);
+	}
 
 	i2c_set_clientdata(client, pdata);
 
-- 
2.20.1