Convert drivers to use the new of_graph_get_remote_node() helper
instead of parsing the endpoint node and then getting the remote device
node. Now drivers can just specify the device node and which
port/endpoint and get back the connected remote device node. The details
of the graph binding are nicely abstracted into the core OF graph code.

This changes some error messages to debug messages (in the graph core).
Graph connections are often "no connects" depending on the particular
board, so we want to avoid spurious messages. Plus the kernel is not a
DT validator.
Signed-off-by: NRob Herring <robh@kernel.org>
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>
Tested-by: NLiviu Dudau <liviu.dudau@arm.com>
Tested-by: NEric Anholt <eric@anholt.net>
Tested-by: NJyri Sarha <jsarha@ti.com>
Tested by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: NSean Paul <seanpaul@chromium.org>

On some boards the hpd pin of a hdmi connector is wired up to a gpio
pin. Since in the DRM world the tfp410 driver is responsible for
handling the connector, add support for hpd gpios in this very driver.
Reviewed-by: NJyri Sarha <jsarha@ti.com>
Signed-off-by: NChristopher Spinrath <christopher.spinrath@rwth-aachen.de>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/2e47786ab3d04078ae70d0c4064f7c4d@rwthex-s1-b.rwth-ad.de

Fixes the following sparse warning:

drivers/gpu/drm/bridge/ti-tfp410.c:223:24: warning:
 symbol 'tfp410_platform_driver' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170209152549.30711-1-weiyj.lk@gmail.com

Add very basic ti-tfp410 DVI transmitter driver. The only feature
separating this from a completely dummy bridge is the EDID read
support trough DDC I2C. Even that functionality should be in a
separate generic connector driver. However, because of missing DRM
infrastructure support the connector is implemented within the bridge
driver. Some tfp410 HW specific features may be added later if needed,
because there is a set of registers behind i2c if it is connected.

This implementation is tested against my new tilcdc bridge support
and it works with BeagleBone DVI-D Cape Rev A3. A DT binding document
is also updated.
Signed-off-by: NJyri Sarha <jsarha@ti.com>
Acked-by: NRob Herring <robh@kernel.org>