From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Stultz Subject: [RFC][PATCH 2/3] drm/bridge: adv7511: Add 200ms delay on power-on Date: Mon, 21 Nov 2016 16:37:31 -0800 Message-ID: <1479775052-28194-3-git-send-email-john.stultz@linaro.org> References: <1479775052-28194-1-git-send-email-john.stultz@linaro.org> Return-path: In-Reply-To: <1479775052-28194-1-git-send-email-john.stultz@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: lkml Cc: John Stultz , David Airlie , Archit Taneja , Wolfram Sang , Lars-Peter Clausen , Laurent Pinchart , dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org 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 Cc: Archit Taneja Cc: Wolfram Sang Cc: Lars-Peter Clausen Cc: Laurent Pinchart Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz --- 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