[media] adv7604: Initialize drive strength to default when using DT
authorLars-Peter Clausen <lars@metafoo.de>
Tue, 29 Nov 2016 11:23:48 +0000 (09:23 -0200)
committerMauro Carvalho Chehab <mchehab@s-opensource.com>
Mon, 30 Jan 2017 17:39:40 +0000 (15:39 -0200)
commitda8892d410db224d9a24104529794e6e37e0c100
tree85b1f1205d653ac116fb28747c196389291ab752
parent32dd9e873bba08fbcf31682c38c76efd90a476e3
[media] adv7604: Initialize drive strength to default when using DT

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>
drivers/media/i2c/adv7604.c