Patch "[media] adv7604: Initialize drive strength to default when using DT" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    [media] adv7604: Initialize drive strength to default when using DT

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     adv7604-initialize-drive-strength-to-default-when-using-dt.patch
and it can be found in the queue-4.4 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 foo@baz Thu Nov  9 18:22:51 CET 2017
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Tue, 29 Nov 2016 09:23:48 -0200
Subject: [media] adv7604: Initialize drive strength to default when using DT

From: Lars-Peter Clausen <lars@metafoo.de>


[ Upstream commit da8892d410db224d9a24104529794e6e37e0c100 ]

The adv7604 driver platform data contains fields for configuring the drive
strength of the output pins. When probing the driver through DT these
fields are not explicitly initialized, which means they are left at 0. This
is a reserved setting for the drive strength configuration though and can
cause signal integrity issues.

Whether these signal integrity issues are visible depends on the PCB
specifics (e.g. the higher the load capacitance for the output the more
visible the issue). But it has been observed on existing solutions at high
pixel clock rates.

Initialize the drive strength settings to the power-on-reset value of the
device when probing through devicetree to avoid this issue.

Fixes: 0e158be0162b ("adv7604: Add DT support")

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/i2c/adv7604.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/media/i2c/adv7604.c
+++ b/drivers/media/i2c/adv7604.c
@@ -2856,6 +2856,9 @@ static int adv76xx_parse_dt(struct adv76
 	state->pdata.alt_data_sat = 1;
 	state->pdata.op_format_mode_sel = ADV7604_OP_FORMAT_MODE0;
 	state->pdata.bus_order = ADV7604_BUS_ORDER_RGB;
+	state->pdata.dr_str_data = ADV76XX_DR_STR_MEDIUM_HIGH;
+	state->pdata.dr_str_clk = ADV76XX_DR_STR_MEDIUM_HIGH;
+	state->pdata.dr_str_sync = ADV76XX_DR_STR_MEDIUM_HIGH;
 
 	return 0;
 }


Patches currently in stable-queue which might be from lars@metafoo.de are

queue-4.4/adv7604-initialize-drive-strength-to-default-when-using-dt.patch