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

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>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250521173204.1.Ic0375a9360698592f27afbf1f60f4996d504ed4f@changeid

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index e90effae11701c5830fec0503849af774fe40d5b..6c45c9e879ece8ff192b11234b6d1e1b5d76208e 100644 (file)
--- 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.
         */