This is a note to let you know that I've just added the patch titled

drm/bridge: adv7511: Re-write the i2c address before EDID probing

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: drm-bridge-adv7511-re-write-the-i2c-address-before-edid-probing.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 3587c856675c45809010c2cee5b21096f6e8e938 Mon Sep 17 00:00:00 2001

From: John Stultz john.stultz@linaro.org Date: Mon, 16 Jan 2017 16:52:52 -0800 Subject: drm/bridge: adv7511: Re-write the i2c address before EDID probing

From: John Stultz john.stultz@linaro.org

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@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 Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Tested-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: John Stultz john.stultz@linaro.org Signed-off-by: Archit Taneja architt@codeaurora.org Link: http://patchwork.freedesktop.org/patch/msgid/1484614372-15342-7-git-send-ema... Signed-off-by: Nhan Nguyen nhan.nguyen.yb@renesas.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c @@ -573,9 +573,17 @@ static int adv7511_get_modes(struct adv7 unsigned int count;

/* Reading the EDID only works if the device is powered */ - if (!adv7511->powered) + if (!adv7511->powered) { + unsigned int edid_i2c_addr = + (adv7511->i2c_main->addr << 1) + 4; + __adv7511_power_on(adv7511);

+ /* Reset the EDID_I2C_ADDR register as it might be cleared */ + regmap_write(adv7511->regmap, ADV7511_REG_EDID_I2C_ADDR, + edid_i2c_addr); + } + edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511);

if (!adv7511->powered)

Patches currently in stable-queue which might be from john.stultz@linaro.org are

queue-4.9/drm-bridge-adv7511-re-write-the-i2c-address-before-edid-probing.patch queue-4.9/drm-bridge-adv7511-rework-adv7511_power_on-off-so-they-can-be-reused-internally.patch queue-4.9/drm-bridge-adv7511-reuse-__adv7511_power_on-off-when-probing-edid.patch