From: "Michel Dänzer" <michel@daenzer.net>
To: ville.syrjala@linux.intel.com
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 10/11] drm: Use vblank timestamps to guesstimate how many vblanks were missed
Date: Mon, 28 Sep 2015 11:57:20 +0900 [thread overview]
Message-ID: <5608AC90.9000305@daenzer.net> (raw)
In-Reply-To: <1442259832-23424-11-git-send-email-ville.syrjala@linux.intel.com>
On 15.09.2015 04:43, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> When lacking am accurate hardware frame counter, we can fall back to
> using the vblank timestamps to guesstimagte how many vblanks have
> elapsed since the last time the vblank counter was updated.
>
> Take the oppostunity to unify the vblank_disable_and_save() and
> drm_handle_vblank_events() to call the same function
> (drm_update_vblank_count()) to perform the vblank updates.
It would be nice to keep the drm_update_vblank_count unification
separate. As it is, it's very hard to keep track of which parts of the
patch are for each logical change.
BTW, I think the fact that I was hitting the problem fixed by 209e4dbc
("drm/vblank: Use u32 consistently for vblank counters") within a few
days indicates that there's another bug which causes the counter to jump
forward with drm_vblank_on/off(). It may not manifest itself with
current Intel hardware because that has a full 32-bit hardware frame
counter, turning the related calculations into no-ops. I haven't had
time to investigate this further yet.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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next prev parent reply other threads:[~2015-09-28 2:57 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-14 19:43 [PATCH 00/11] drm: vblank fixes and timestamp based missed vblank guesttimation ville.syrjala
2015-09-14 19:43 ` [PATCH 01/11] drm: s/int crtc/unsigned int pipe/ straggles ville.syrjala
2015-09-15 7:29 ` Thierry Reding
2015-09-22 9:05 ` Daniel Vetter
2015-09-14 19:43 ` [PATCH 02/11] drm: Move timestamping constants into drm_vblank_crtc ville.syrjala
2015-09-16 13:21 ` Maarten Lankhorst
2015-09-14 19:43 ` [PATCH 03/11] drm: Stop using linedur_ns and pixeldur_ns for vblank timestamps ville.syrjala
2015-09-14 19:43 ` [PATCH 04/11] drm: Kill pixeldur_ns ville.syrjala
2015-09-14 19:43 ` [PATCH 05/11] drm/i915: Fix vblank count variable types ville.syrjala
2015-09-14 19:43 ` [PATCH 06/11] drm: Pass flags to drm_update_vblank_count() ville.syrjala
2015-09-14 19:43 ` [PATCH 07/11] drm: Limit the number of .get_vblank_counter() retries ville.syrjala
2015-09-14 19:43 ` [PATCH 08/11] drm: Clean up drm_calc_vbltimestamp_from_scanoutpos() vbl_status ville.syrjala
2015-09-14 19:43 ` [PATCH 09/11] drm: store_vblank() is never called with NULL timestamp ville.syrjala
2015-09-14 19:43 ` [PATCH 10/11] drm: Use vblank timestamps to guesstimate how many vblanks were missed ville.syrjala
2015-09-28 2:57 ` Michel Dänzer [this message]
2015-09-30 14:42 ` Thierry Reding
2015-09-14 19:43 ` [PATCH 11/11] drm: Fix vblank timestamp races ville.syrjala
2015-09-22 9:10 ` Daniel Vetter
2015-09-22 11:15 ` Maarten Lankhorst
2015-09-22 11:31 ` Daniel Vetter
2015-09-22 12:36 ` Ville Syrjälä
2015-09-22 12:57 ` Daniel Vetter
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