On 08/07/2014 08:50 AM, Daniel Vetter wrote:
On Thu, Aug 7, 2014 at 2:50 AM, Mario Kleiner
<mario.kleiner.de@xxxxxxxxx> wrote:
I'm not sure about all the new embedded drivers, if they have hw vblank
counters?
Quick grep says a lot don't have it or at least not implemented - they
use drm_vblank_count. Thinking about this, should we use that as a
signal to also set dev->vblnka_disable_allowed = false in
drm_vblank_init?
-Daniel
dev->vblank_disable_allowed = false; is already the default set in drm_vblank_init().
I think it was the idea of that flag that drivers which support a somewhat correct vblank dis/enable (= have useable hw vblank counters) opt-in to the vblank disable after some idle time by setting it to true.
The strange thing is that unconditional dev->vblank_disable_allowed =
true in drm_vblank_post_modeset()?
It's there since the first introduction of the flag.
The i915, gma500, armada and exynos drivers explicitely set the flag to
true to opt-in to the auto vblank disable. radeon gets it implicitely
set by calling the vblank_post_modeset function. Tegra also gets it via
the post_modeset, and nouveau on old cards with nv04 display engine.
armada, exynos and tegra don't have proper hw vblank counter queries,
but opt-in, so those will lose vblank counts whenever vblank irqs get
turned off.
It's a bit all over the place.
-mario
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