Re: [PATCH 1/2] drm/radeon: Use drm_vblank_off/on to fix vblank counter trouble.

On 21.01.2016 17:16, Mario Kleiner wrote:

This patch replaces calls to drm_vblank_pre/post_modeset in the drivers dpms code with calls to drm_vblank_off/on, as recommended for drivers with hw counters that reset to zero during modeset.

Sounds like you fell for the drm_vblank_on/off propaganda. :( This was working fine with drm_vblank_pre/post_modeset, that it broke is simply a regression.

I'm not against switching to drm_vblank_on/off for 4.6, but it's not a solution for older kernels.