On Wed, 2011-04-27 at 11:08 +0200, Michel Dänzer wrote:
On Mit, 2011-04-27 at 18:58 +1000, Christopher James Halse Rogers wrote:
On Wed, 2011-04-27 at 10:32 +0200, Michel Dänzer wrote:
On Mit, 2011-04-27 at 16:10 +1000, christopher.halse.rogers@canonical.com wrote:
From: Christopher James Halse Rogers christopher.halse.rogers@canonical.com
This is the least-bad behaviour. It means that we signal the vblank event before it actually happens, but since we're disabling vblanks there's no guarantee that it will *ever* happen otherwise.
This may indeed be the best we can do for events that are pending when the CRTC is disabled[0], but I can't see anything that would prevent new events from getting scheduled (or synchronous vblank waits from timing out) while the CRTC is disabled?
[0] Though it might unnecessarily send events prematurely when the CRTC is just disabled temporarily, e.g. as part of a modeset.
Also, this patch won't seem to help at all for other drivers which don't call drm_vblank_off() directly when disabling a CRTC.
This is true. On the other hand, the other drivers don't wedge the vblank code into a state where vblanks cannot be re-enabled. So it's only a problem when disabling one of 2+ monitors on those drivers,
And with DPMS?
whereas it's easily triggerable on single monitor systems on intel.
Anyway, this patch is probably good at least as a preliminary fix for the inconsistent vblank state with the intel driver.
Maybe it would be possible to move those calls to core code, and/or only force sending out events when the CRTC isn't just getting disabled temporarily.
As in: have the core modesetting code call drm_vblank_off before making the driver-specific calls when disabling a crtc? I'll look into it - that would appear to be a more general solution.
Yeah, something like that, thanks.
Ok. This appears to be surprisingly difficult. Particularly, the vblank code indexes crtcs based on the driver-private numbering, and there doesn't appear to be a generic interface to grab this number; Intel uses the DRM_IOCTL_I915_GET_PIPE_FROM_CRTC_ID ioctl, radeon uses something different.
I'll see what I can come up with, but I don't think I'm sufficiently familiar with the kms code to quickly come up with a nice API.