# Re: \[RFT PATCHv2\] drm/exynos: Enable DP clock to fix display on Exynos5250 and other

- From: Javier Martinez Canillas \<hidden\>
- Date: 2015-03-27 19:21:37 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2015/03/4461021
- Thread: https://ratatoskr.run/dri-devel/2015/03/4460847/t.md

```text
Hello Krzysztof,

On 03/27/2015 05:08 PM, Krzysztof Kozlowski wrote:
> After adding display power domain for Exynos5250 in commit
> 2d2c9a8d0a4f ("ARM: dts: add display power domain for exynos5250") the
> display on Chromebook Snow and others stopped working after boot.
> 
> The reason for this suggested Andrzej Hajda: the DP clock was disabled.
> This clock is required by Display Port and is enabled by bootloader.
> However when FIMD driver probing was deferred, the display power domain
> was turned off. This effectively reset the value of DP clock enable
> register.
> 
> When exynos-dp is later probed, the clock is not enabled and display is
> not properly configured:
> 
> exynos-dp 145b0000.dp-controller: Timeout of video streamclk ok
> exynos-dp 145b0000.dp-controller: unable to config video
> 
> Signed-off-by: Krzysztof Kozlowski <redacted>
> Reported-by: Javier Martinez Canillas <redacted>
> Fixes: 2d2c9a8d0a4f ("ARM: dts: add display power domain for exynos5250")
> Cc: <redacted>
> 
> ---
> 
> This should fix issue reported by Javier [1][2].
>

I tested this patch and does indeed solves both issues I reported
The exynos-dp probe deferral does not make the display to not be
working and also disabling and enabling the display with:

with /sys/devices/platform/exynos-drm/graphics/fb0/blank works.

Thanks a lot for fixing this issue.

On an Exynos5250 Snow Chromebook:

Tested-by: Javier Martinez Canillas <redacted>

Best regards,
Javier
```