[RFC][PATCH 2/3] drm/bridge: adv7511: Add 200ms delay on power-on

From: John Stultz
Date: Mon Nov 21 2016 - 19:37:42 EST

Secton 4.1 of the adv7511 programming guide advises one waits
200ms after powering on the chip before trying to communicate
with it via i2c. Not doing so can cause reliability issues when
probing the EDID.


So this patch simply adds a 200ms sleep at the end of the
power_on path. This greatly improves EDID probing reliabilty
on hotplug with the HiKey device.

Cc: David Airlie <airlied@xxxxxxxx>
Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
Cc: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index b240e05..2114a4c 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -361,6 +361,8 @@ static void __adv7511_power_on(struct adv7511 *adv7511)

+ msleep(200);
if (adv7511->type == ADV7533)