[PATCH 4.4.y] drm: adv7511: Re-write the i2c address before EDID probing

[Nhan Ngoc. Nguyen]

This patch is ported from linux stable 4.9, commit 3587c856675c45809010c2cee5b21096f6e8e938.
So I think I don't need to port on version 4.9.

On 9/8/2017 2:21 PM, Greg KH wrote:
> On Fri, Sep 08, 2017 at 09:46:02AM +0700, Nhan Nguyen wrote:
>> commit 3587c856675c45809010c2cee5b21096f6e8e938 upstream.
>>
>> I've found that by just turning the chip on and off via the
>> POWER_DOWN register, I end up getting i2c_transfer errors on
>> HiKey.
>>
>> Investigating further, it turns out that some of the register
>> state in hardware is getting lost, as the device registers are
>> reset when the chip is powered down.
>>
>> Thus this patch simply re-writes the i2c address to the
>> ADV7511_REG_EDID_I2C_ADDR register to ensure its properly set
>> before we try to read the EDID data.
>>
>> 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
>> Cc: stable at vger.kernel.org
>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> Tested-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> Signed-off-by: John Stultz <john.stultz at linaro.org>
>> Signed-off-by: Archit Taneja <architt at codeaurora.org>
>> Signed-off-by: Thong Ho <thong.ho.px at rvc.renesas.com>
>> Signed-off-by: Nhan Nguyen <nhan.nguyen.yb at renesas.com>
>> Link: http://patchwork.freedesktop.org/patch/msgid/1484614372-15342-7-git-send-email-john.stultz@linaro.org
>> ---
>>   drivers/gpu/drm/i2c/adv7511.c | 11 +++++++----
>>   1 file changed, 7 insertions(+), 4 deletions(-)
> Can you provide a working backport for the 4.9-stable kernel as well?
>
> Also, please do not send backports for patches that do not also work in
> newer stable kernels, like 4.9, I backported some of this series there,
> but I shouldn't have to check for you.
>
> thanks,
>
> greg k-h