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%3Ba=su...
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