[PATCH] drm/panel-edp: Clarify the `prepare_to_enable` description in comments

[PATCH] drm/panel-edp: Clarify the `prepare_to_enable` description in comments

[Douglas Anderson]

It's unclear why I originally wrote in the description of
`prepare_to_enable` that "This is not specified in a standard way on
eDP timing diagrams" and then also wrote "It is effectively the time
from HPD going high till you can turn on the backlight." It seems
pretty clear that it's (T4+T5+T6+T8)-min. Either I was confused when I
wrote this or I was looking at some strange panel datasheet that I can
no longer find.

Update the description of the field so it's easier for people to fill
this in. Couch the description with "usually" in case there really was
some weird datasheet where things were specified in a different way.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/gpu/drm/panel/panel-edp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index 9adbe0f11421..74f5f9006a5b 100644
--- a/drivers/gpu/drm/panel/panel-edp.c
+++ b/drivers/gpu/drm/panel/panel-edp.c
@@ -113,7 +113,7 @@ struct panel_delay {
 	 *     // do fixed enable delay
 	 *     // enforce prepare_to_enable min time
 	 *
-	 * This is not specified in a standard way on eDP timing diagrams.
+	 * This is usually (T4+T5+T6+T8)-min on eDP timing diagrams.
 	 * It is effectively the time from HPD going high till you can
 	 * turn on the backlight.
 	 */
-- 
2.49.0.1151.ga128411c76-goog

Re: [PATCH] drm/panel-edp: Clarify the `prepare_to_enable` description in comments

[Neil Armstrong]

On 22/05/2025 02:32, Douglas Anderson wrote:
> It's unclear why I originally wrote in the description of
> `prepare_to_enable` that "This is not specified in a standard way on
> eDP timing diagrams" and then also wrote "It is effectively the time
> from HPD going high till you can turn on the backlight." It seems
> pretty clear that it's (T4+T5+T6+T8)-min. Either I was confused when I
> wrote this or I was looking at some strange panel datasheet that I can
> no longer find.
> 
> Update the description of the field so it's easier for people to fill
> this in. Couch the description with "usually" in case there really was
> some weird datasheet where things were specified in a different way.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
>   drivers/gpu/drm/panel/panel-edp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> index 9adbe0f11421..74f5f9006a5b 100644
> --- a/drivers/gpu/drm/panel/panel-edp.c
> +++ b/drivers/gpu/drm/panel/panel-edp.c
> @@ -113,7 +113,7 @@ struct panel_delay {
>   	 *     // do fixed enable delay
>   	 *     // enforce prepare_to_enable min time
>   	 *
> -	 * This is not specified in a standard way on eDP timing diagrams.
> +	 * This is usually (T4+T5+T6+T8)-min on eDP timing diagrams.
>   	 * It is effectively the time from HPD going high till you can
>   	 * turn on the backlight.
>   	 */

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH] drm/panel-edp: Clarify the `prepare_to_enable` description in comments

[Neil Armstrong]

Hi,

On Wed, 21 May 2025 17:32:05 -0700, Douglas Anderson wrote:
> It's unclear why I originally wrote in the description of
> `prepare_to_enable` that "This is not specified in a standard way on
> eDP timing diagrams" and then also wrote "It is effectively the time
> from HPD going high till you can turn on the backlight." It seems
> pretty clear that it's (T4+T5+T6+T8)-min. Either I was confused when I
> wrote this or I was looking at some strange panel datasheet that I can
> no longer find.
> 
> [...]

Thanks, Applied to https://gitlab.freedesktop.org/drm/misc/kernel.git (drm-misc-next)

[1/1] drm/panel-edp: Clarify the `prepare_to_enable` description in comments
      https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/0b3d99425891e3c4a87259afb88fbd1168dc7707

-- 
Neil