lkml.org 
[lkml]   [2016]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC][PATCH 2/3] drm/bridge: adv7511: Add 200ms delay on power-on
    Date
    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@linux.ie>
    Cc: Archit Taneja <architt@codeaurora.org>
    Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
    Cc: Lars-Peter Clausen <lars@metafoo.de>
    Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
    Cc: dri-devel@lists.freedesktop.org
    Signed-off-by: John Stultz <john.stultz@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
    \
     
     \ /
      Last update: 2016-11-22 01:38    [W:6.627 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site