Hi All,
Is there any callback available, at the crtc level, that can validate the probed modes before making them available for userspace? I mean: I know that there is connector->mode_valid(), but I couldn't find any equivalent crtc->mode_valid(). I found mode_fixup() but this is called after giving the mode to userspace, which is not what I need.
For reference here is the situation I'm facing:
ARCPGU is a DRM driver that uses ADV7511 as connector/bridge. The PGU encodes raw video into a stream that ADV can understands and in order to do this it needs a pixel clock. Currently this pixel clock value is fixed, so technically arcpgu driver supports only one video mode. There is a patch currently on discussion that adds more supported frequencies for arcpgu, but there are still some frequencies that will not be supported. This is NOT a limitation in ADV7511, so it doesn't make sense to limit the available modes in adv, we could instead limit the modes in the crtc level (i.e. the pgu).
In order to know if a mode can be displayed or not it is as simple as call clk_round_rate() and check if the returned frequency is the same. But in order to do this I need some sort of callback that is called at the crtc level and before delivering modes to userspace.
I believe this would be a good addition to arcpgu because this way we wouldn't "fool" userspace by delivering modes that will fail in atomic check. The user may still specify manually a mode, this will still fail in atomic check, but the difference is that this mode will not be in the probed list.
Best regards,
Jose Miguel Abreu