drm/exynos: fimd: vrefresh is zero

[Andrzej Hajda]

On 05/05/2016 11:12 AM, Andrzej Hajda wrote:
> 
> Regarding the initial question, mode->vrefresh is set in
> drm_helper_probe_single_connector_modes. I guess division by zero could
> be caused by lack of clock in timings provided by dts timing node.
> As I remember in the past dts timings were passed without provided
> clock, in such case driver calculated mode->clock for some default value
> of vrefresh (60Hz for fimd if I remember correctly). Later validation
> code was added and the clock should be always provided.
> DTS files were updated after some time and the recalculation code was
> removed from fimd driver. So it is possible you are a victim of this change.

One more thing, I have looked at Exynos DTS files in mainline. In case
of exynos5*.dts files clock-frequency is set to 50000, it is of course
insanely low value and vrefresh calculated for such timings will be 0.
So please verify if clock-frequency is not too low in your case.

Regards
Andrzej

> 
> Regarding usage by drivers, from a quick look it seems to be used for
> something more than debugging by:
> - amdgpu,
> - exynos,
> - adv7511,
> - intel_dp(?),
> - mdp5_cmd_encoder(?),
> - nouveau,
> - omap(?),
> - tilcdc.
> 
> Regards
> Andrzej
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