[drm/exynos-fimd] Display regression in v3.12-rc1

[Andrzej Hajda]

Hi Sachin,

Could you test it with removed display-timings::clock-frequency property.
Currently in arch/arm/boot/dts/exynos4210-origen.dts
display-timings::clock-frequency is set to 50000,
this is incorrect value. With the property removed fimd calculates
clock-frequency from other properties with assumption of default
60Hz refresh rate.

It could work before because of_get_fb_videomode calculated refresh rate
from display-timings and with clock 50000, the result was 0(due to
rounding down in some division),
so fimd assumed he should use default refresh rate of 60Hz.

Regards
Andrzej

On 09/18/2013 07:22 AM, Sachin Kamat wrote:
> Hi Andrzej ,
>
> I was testing the latest Linux kernel release (v3.12-rc1) on
> Exynos4210 based Origen board.
> I found a display regression with that. I do not get any display on
> the LCD (other than backlight) with the latest kernel. Git bisect
> pointed me to the following commit:
> 111e6055d4e0d35c6a4b6cd37d7bb00a88eaffb4 ("drm/exynos: fimd: replace
> struct fb_videomode with videomode"). Reverting this patch does not
> cause the issue. Let me know if you need any other info to help
> identify the problem.
>