drm/exynos: fimd: vrefresh is zero

[Alex Deucher]

On Sat, Apr 30, 2016 at 5:37 PM, Tobias Jakobi
<tjakobi at math.uni-bielefeld.de> wrote:
> Hello,
>
> while playing around with FIMD enabled, I noticed that when first using
> the device a zero division was triggered in fimd_calc_clkdiv(). I
> remembered that I had a similar issue some time ago.
>
> I added a stub fimd_atomic_check() which shows that vrefresh is zero
> when fimd_calc_clkdiv() is called.
>
> [  164.059361] [drm:exynos_plane_mode_set] plane : offset_x/y(0,0),
> width/height(1366,768)
> [  164.067175] [drm:fimd_atomic_check] xres=1366, yres=768, refresh=0,
> intl=0
> [  164.074198] [drm:drm_atomic_helper_check_planes] [CRTC:24:crtc-0]
> atomic driver check failed
>
> I went back to the git log and noticed that some time ago in
> 50bbfbffa5c894def440ce8157dfe53e60960d35 the fimd_mode_fixup() call was
> removed.
>
> I'm now wondering where exactly vrefresh is set to a sane value. As far
> as I can see of_get_videomode() is used to fetch the video mode from the
> DT, and drm_display_mode_from_videomode() is used to convert it. However
> vrefresh is nowhere set.
>
> So is something broken here, or am I missing something?
>

There is no guarantee that vrefresh is actually set.  I think the only
way to reliably get it is to call drm_mode_vrefresh().


Alex