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

[John Stultz]

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.

See:
http://www.analog.com/media/en/technical-documentation/user-guides/ADV7511_Programming_Guide.pdf

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 at linux.ie>
Cc: Archit Taneja <architt at codeaurora.org>
Cc: Wolfram Sang <wsa+renesas at sang-engineering.com>
Cc: Lars-Peter Clausen <lars at metafoo.de>
Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Cc: dri-devel at lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz at linaro.org>
---
 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)
 	 */
 	regcache_sync(adv7511->regmap);
 
+	msleep(200);
+
 	if (adv7511->type == ADV7533)
 		adv7533_dsi_power_on(adv7511);
 }
-- 
2.7.4