[PATCH] video: rockchip: Add missing dpcd_write() call to link_train_ce()

[Simon Glass]

On Tue, 6 Oct 2020 at 14:40, Alper Nebi Yasak <alpernebiyasak at gmail.com> wrote:
>
> Found this by comparing it to the coreboot driver, a form of this call
> was introduced there in their commit b9a7877568cf ("rockchip/*: refactor
> edp driver"). This is copy-pasted from U-Boot's link_train_cr() slightly
> above it.
>
> Without this on a gru-kevin chromebook, I have:
>
>     clock recovery at voltage 0 pre-emphasis 0
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     channel eq failed, ret=-5
>     link train failed!
>     rk_vop_probe() Device failed: ret=-5
>
> With this, it looks like training succeeds:
>
>     clock recovery at voltage 0 pre-emphasis 0
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
>     using signal parameters: voltage 0.4V pre_emph 3.5dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 6dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 6dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 6dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 6dB
>     using signal parameters: voltage 0.4V pre_emph 6dB
>     requested signal parameters: lane 0 voltage 0.4V pre_emph 0dB
>     requested signal parameters: lane 1 voltage 0.4V pre_emph 0dB
>     requested signal parameters: lane 2 voltage 0.4V pre_emph 0dB
>     requested signal parameters: lane 3 voltage 0.4V pre_emph 0dB
>     using signal parameters: voltage 0.4V pre_emph 0dB
>     channel eq at voltage 0 pre-emphasis 0
>     config video failed
>     rk_vop_probe() Device failed: ret=-110
>
> The "config video failed" error also goes away when I disable higher
> log levels, and it claims to have successfully probed the device.
>
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak at gmail.com>
> ---
> I'm testing this with a lot of other patches to make the board work. The
> actual tree I'm using is available here:
>
>     https://github.com/alpernebbi/u-boot/commits/rk3399-gru-kevin/wip
>     (currently at commit c0dc4b42afe770671ce7bb0dd519d894a3acdea0)
>
>  drivers/video/rockchip/rk_edp.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>

Reviewed-by: Simon Glass <sjg at chromium.org>