[PATCH] drm/bridge: analogix_dp: Improve panel on time

[PATCH] drm/bridge: analogix_dp: Improve panel on time

[Sean Paul]

In order to reduce the time required to turn on the panel, this patch
makes 2 assumptions:
1- In detect(): if there's a panel, we're connected.
2- In get_modes(): if there's a panel, let the panel driver decide if
   it should prepare/unprepare in order to get the modes.

The first is straightforward, and shouldn't need further explanation. The
second should eliminate the prepare/unprepare delays from get_modes() in
most cases, since panels generally hardcode their modes in the driver as
opposed to reading EDID. If a panel does need to read EDID, it should be
responsible for ensuring it's in a state in which it can.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 23 ++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index e9c9aeb..18f622a 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -924,15 +924,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
 	struct edid *edid;
 	int ret, num_modes = 0;
 
-	ret = analogix_dp_prepare_panel(dp, true, false);
-	if (ret) {
-		DRM_ERROR("Failed to prepare panel (%d)\n", ret);
-		return 0;
-	}
-
 	if (dp->plat_data->panel) {
 		num_modes += drm_panel_get_modes(dp->plat_data->panel);
 	} else {
+		ret = analogix_dp_prepare_panel(dp, true, false);
+		if (ret) {
+			DRM_ERROR("Failed to prepare panel (%d)\n", ret);
+			return 0;
+		}
+
 		edid = drm_get_edid(connector, &dp->aux.ddc);
 		if (edid) {
 			drm_mode_connector_update_edid_property(&dp->connector,
@@ -940,15 +940,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
 			num_modes += drm_add_edid_modes(&dp->connector, edid);
 			kfree(edid);
 		}
+
+		ret = analogix_dp_prepare_panel(dp, false, false);
+		if (ret)
+			DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
 	}
 
 	if (dp->plat_data->get_modes)
 		num_modes += dp->plat_data->get_modes(dp->plat_data, connector);
 
-	ret = analogix_dp_prepare_panel(dp, false, false);
-	if (ret)
-		DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
-
 	return num_modes;
 }
 
@@ -972,6 +972,9 @@ analogix_dp_detect(struct drm_connector *connector, bool force)
 	enum drm_connector_status status = connector_status_disconnected;
 	int ret;
 
+	if (dp->plat_data->panel)
+		return connector_status_connected;
+
 	ret = analogix_dp_prepare_panel(dp, true, false);
 	if (ret) {
 		DRM_ERROR("Failed to prepare panel (%d)\n", ret);
-- 
2.8.0.rc3.226.g39d4020

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Re: [PATCH] drm/bridge: analogix_dp: Improve panel on time

[Archit Taneja]

On 09/07/2016 04:53 PM, Sean Paul wrote:
> In order to reduce the time required to turn on the panel, this patch
> makes 2 assumptions:
> 1- In detect(): if there's a panel, we're connected.
> 2- In get_modes(): if there's a panel, let the panel driver decide if
>     it should prepare/unprepare in order to get the modes.
>
> The first is straightforward, and shouldn't need further explanation. The
> second should eliminate the prepare/unprepare delays from get_modes() in
> most cases, since panels generally hardcode their modes in the driver as
> opposed to reading EDID. If a panel does need to read EDID, it should be
> responsible for ensuring it's in a state in which it can.

Looks fine to me. I'll queue it to drm-misc if there are no comments on
it in the next couple days.

Thanks,
Archit

>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> ---
>   drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 23 ++++++++++++----------
>   1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index e9c9aeb..18f622a 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -924,15 +924,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
>   	struct edid *edid;
>   	int ret, num_modes = 0;
>
> -	ret = analogix_dp_prepare_panel(dp, true, false);
> -	if (ret) {
> -		DRM_ERROR("Failed to prepare panel (%d)\n", ret);
> -		return 0;
> -	}
> -
>   	if (dp->plat_data->panel) {
>   		num_modes += drm_panel_get_modes(dp->plat_data->panel);
>   	} else {
> +		ret = analogix_dp_prepare_panel(dp, true, false);
> +		if (ret) {
> +			DRM_ERROR("Failed to prepare panel (%d)\n", ret);
> +			return 0;
> +		}
> +
>   		edid = drm_get_edid(connector, &dp->aux.ddc);
>   		if (edid) {
>   			drm_mode_connector_update_edid_property(&dp->connector,
> @@ -940,15 +940,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
>   			num_modes += drm_add_edid_modes(&dp->connector, edid);
>   			kfree(edid);
>   		}
> +
> +		ret = analogix_dp_prepare_panel(dp, false, false);
> +		if (ret)
> +			DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
>   	}
>
>   	if (dp->plat_data->get_modes)
>   		num_modes += dp->plat_data->get_modes(dp->plat_data, connector);
>
> -	ret = analogix_dp_prepare_panel(dp, false, false);
> -	if (ret)
> -		DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
> -
>   	return num_modes;
>   }
>
> @@ -972,6 +972,9 @@ analogix_dp_detect(struct drm_connector *connector, bool force)
>   	enum drm_connector_status status = connector_status_disconnected;
>   	int ret;
>
> +	if (dp->plat_data->panel)
> +		return connector_status_connected;
> +
>   	ret = analogix_dp_prepare_panel(dp, true, false);
>   	if (ret) {
>   		DRM_ERROR("Failed to prepare panel (%d)\n", ret);
>

-- 
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