From: Keith Packard <keithp@keithp.com>
To: Jesse Barnes <jbarnes@virtuousgeek.org>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: don't set unpin_work if vblank_get fails
Date: Mon, 22 Aug 2011 11:45:05 -0700 [thread overview]
Message-ID: <yunei0d5lqm.fsf@aiko.keithp.com> (raw)
In-Reply-To: <20110822110531.57d85c32@jbarnes-desktop>
[-- Attachment #1.1: Type: text/plain, Size: 1645 bytes --]
On Mon, 22 Aug 2011 11:05:31 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> This fixes a race where we may try to finish a page flip and decrement
> the refcount even if our vblank_get failed and we ended up with a
> spurious flip pending interrupt.
>
> Fixes https://bugs.freedesktop.org/show_bug.cgi?id=34211.
>
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 2319f62..0910537 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6896,6 +6896,10 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
> work->old_fb_obj = intel_fb->obj;
> INIT_WORK(&work->work, intel_unpin_work_fn);
>
> + ret = drm_vblank_get(dev, intel_crtc->pipe);
> + if (ret)
> + goto free_work;
> +
> /* We borrow the event spin lock for protecting unpin_work */
> spin_lock_irqsave(&dev->event_lock, flags);
> if (intel_crtc->unpin_work) {
> @@ -6906,6 +6910,11 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
> return -EBUSY;
You'll need a drm_vblank_put above this return.
> }
> intel_crtc->unpin_work = work;
> + /*
> + * Past this point, if we fail we'll let the flip completion code
> + * clean up the vblank refcount and pin work. It'll be a spurious
> + * completion, but we handle that case.
> + */
I don't see how this is going to happen reliably; the hardware will have
to generate a suitable interrupt, which on IRL and later will have to be
an actual page flip interrupt.
--
keith.packard@intel.com
[-- Attachment #1.2: Type: application/pgp-signature, Size: 189 bytes --]
[-- Attachment #2: Type: text/plain, Size: 159 bytes --]
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2011-08-22 18:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-22 18:05 [PATCH] drm/i915: don't set unpin_work if vblank_get fails Jesse Barnes
2011-08-22 18:45 ` Keith Packard [this message]
2011-08-29 16:44 ` Jesse Barnes
2011-08-29 16:45 ` Jesse Barnes
2011-09-20 4:04 ` Keith Packard
2011-11-11 20:36 ` Jesse Barnes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=yunei0d5lqm.fsf@aiko.keithp.com \
--to=keithp@keithp.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jbarnes@virtuousgeek.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).