From: Chris Wilson <chris@chris-wilson.co.uk>
To: DRI Development <dri-devel@lists.freedesktop.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH] drm: kms_helper: don't lose hotplug event
Date: Thu, 25 Oct 2012 10:07:46 +0100 [thread overview]
Message-ID: <6c3329$6th7mi@orsmga002.jf.intel.com> (raw)
In-Reply-To: <1351106213-3809-1-git-send-email-daniel.vetter@ffwll.ch>
On Wed, 24 Oct 2012 21:16:53 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> There's a race window (small for hpd, 10s large for polled outputs)
> where userspace could sneak in with an unrelated connnector probe
> ioctl call and eat the hotplug event (since neither the hpd nor the
> poll code see a state change).
>
> To avoid this, check whether the connector state changes in all other
> ->detect calls (in the current helper code that's only probe_single)
> and if that's the case, fire off a hotplug event. Note that we can't
> directly call the hotplug event handler, since that expects that no
> locks are held (due to reentrancy with the fb code to update the kms
> console).
>
> Also, this requires that drivers using the probe_single helper
> function set up the poll work. All current drivers do that already,
> and with the reworked hpd handling there'll be no downside to
> unconditionally setting up the poll work any more.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Aye, we do want the hotplug notification for the desktop to respond to
if the user happens to steal it by haplessly querying the system with
xrandr. lgtm,
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
next prev parent reply other threads:[~2012-10-25 9:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 19:16 [PATCH] drm: kms_helper: don't lose hotplug event Daniel Vetter
2012-10-25 9:07 ` Chris Wilson [this message]
2012-11-23 16:42 ` Daniel Vetter
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