From: "Michel Dänzer" <michel@daenzer.net>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 5/5] drm/i915: Allow vblank interrupts during modeset and eliminate some vblank races
Date: Tue, 25 Feb 2014 11:58:26 +0900 [thread overview]
Message-ID: <1393297106.27769.48.camel@thor.local> (raw)
In-Reply-To: <20140224121101.GN3852@intel.com>
On Mon, 2014-02-24 at 14:11 +0200, Ville Syrjälä wrote:
> On Mon, Feb 24, 2014 at 12:48:55PM +0900, Michel Dänzer wrote:
> > On Fre, 2014-02-21 at 21:03 +0200, ville.syrjala@linux.intel.com wrote:
> > >
> > > We can kill of the drm_vblank_{pre,post}_modeset() calls since those are
> > > there simply to make drm_vblank_get() fail during a modeset.
> >
> > Actually, their original purpose was to keep the DRM vblank counter
> > consistent across modesets, assuming the modeset resets the hardware
> > vblank counter.
>
> I see. Well, actually I really don't. The code is too funky for me to
> tell what it actually ends up doing. The obvious way would be to
> resample the hardware counter at drm_vblank_post_modeset(), which the
> code certainly doesn't do. But maybe it did something sensible in the
> past.
When the pre/post-modeset hooks were originally added, it worked like
this: the pre-modeset hook enabled the vblank interrupt, which updated
the DRM vblank counter from the driver/HW counter. The post-modeset hook
disabled the vblank interrupt again, which recorded the post-modeset
driver/HW counter value.
But the vblank code has changed a lot since then, not sure it still
works like that.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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next prev parent reply other threads:[~2014-02-25 2:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-21 19:03 [PATCH 0/5] drm: Allow vblank interrupts during modeset and make the code less racy ville.syrjala
2014-02-21 19:03 ` [PATCH 1/5] drm: Use correct spinlock flavor in drm_vblank_get() ville.syrjala
2014-02-26 19:24 ` [Intel-gfx] " Jesse Barnes
2014-02-21 19:03 ` [PATCH 2/5] drm: Make the vblank disable timer per-crtc ville.syrjala
2014-02-26 19:32 ` Jesse Barnes
2014-02-21 19:03 ` [PATCH 3/5] drm: Allow the driver to reject vblank requests only when it really has the vblank interrupts disabled ville.syrjala
2014-02-26 19:41 ` Jesse Barnes
2014-03-04 9:24 ` Daniel Vetter
2014-03-05 12:38 ` Ville Syrjälä
2014-03-05 13:55 ` Daniel Vetter
2014-02-21 19:03 ` [PATCH 4/5] drm: Allow reenabling of vblank interrupts even if refcount>0 ville.syrjala
2014-02-26 19:44 ` Jesse Barnes
2014-03-04 9:16 ` Daniel Vetter
2014-03-05 12:33 ` Ville Syrjälä
2014-02-21 19:03 ` [PATCH 5/5] drm/i915: Allow vblank interrupts during modeset and eliminate some vblank races ville.syrjala
2014-02-24 3:48 ` Michel Dänzer
2014-02-24 12:11 ` Ville Syrjälä
2014-02-25 2:58 ` Michel Dänzer [this message]
2014-02-26 19:48 ` Jesse Barnes
2014-03-04 9:13 ` Daniel Vetter
2014-05-28 9:12 ` Michel Dänzer
2014-05-28 11:19 ` [Intel-gfx] " Ville Syrjälä
2014-05-29 4:11 ` Michel Dänzer
2014-05-29 10:56 ` Daniel Vetter
2014-05-30 3:13 ` Michel Dänzer
2014-02-28 8:56 ` Ville Syrjälä
2014-03-04 9:15 ` Daniel Vetter
-- strict thread matches above, loose matches on Subject: below --
2025-05-07 21:55 Morales Manuel
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