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From: Keith Packard <keithp@keithp.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device
Date: Tue, 17 Dec 2013 16:14:11 -0800	[thread overview]
Message-ID: <868uvjrp64.fsf@miki.keithp.com> (raw)
In-Reply-To: <20131217185742.GP22448@nuc-i3427.alporthouse.com>


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Chris Wilson <chris@chris-wilson.co.uk> writes:

> Ok, so as no vgaarb_clients have yet been registered and so the call to
> grab the IO resource does not actually disable VGA IO routing to the
> nvidia card.

Yikes! This explains a lot.

> If you care to update the changelog to explain the problem is that
> vgaarb is ineffective before all clients are registered, then I think
> this is a good temporary hack. It should be possible for vgaarb to mark
> resources as locked if the device is interpretting IO access and has no
> method for disabling the IO grab (and then a vga_tryget() check here).

Sounds like vgaarb should not assume that all devices using VGA are
registered drivers. That also sounds like a significantly harder fix.

If SR01 is required before disabling VGA, then perhaps we should not
disable VGA at all in this case though. That sounds safer, although if
VGA was enabled, it will suck a bit more power?

-- 
keith.packard@intel.com

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_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
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WARNING: multiple messages have this Message-ID (diff)
From: Keith Packard <keithp@keithp.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device
Date: Tue, 17 Dec 2013 16:14:11 -0800	[thread overview]
Message-ID: <868uvjrp64.fsf@miki.keithp.com> (raw)
In-Reply-To: <20131217185742.GP22448@nuc-i3427.alporthouse.com>

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Chris Wilson <chris@chris-wilson.co.uk> writes:

> Ok, so as no vgaarb_clients have yet been registered and so the call to
> grab the IO resource does not actually disable VGA IO routing to the
> nvidia card.

Yikes! This explains a lot.

> If you care to update the changelog to explain the problem is that
> vgaarb is ineffective before all clients are registered, then I think
> this is a good temporary hack. It should be possible for vgaarb to mark
> resources as locked if the device is interpretting IO access and has no
> method for disabling the IO grab (and then a vga_tryget() check here).

Sounds like vgaarb should not assume that all devices using VGA are
registered drivers. That also sounds like a significantly harder fix.

If SR01 is required before disabling VGA, then perhaps we should not
disable VGA at all in this case though. That sounds safer, although if
VGA was enabled, it will suck a bit more power?

-- 
keith.packard@intel.com

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  reply	other threads:[~2013-12-18  0:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-17 17:12 [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device Keith Packard
2013-12-17 17:12 ` Keith Packard
2013-12-17 17:27 ` Chris Wilson
2013-12-17 17:27   ` [Intel-gfx] " Chris Wilson
2013-12-17 18:17   ` Keith Packard
2013-12-17 18:57     ` Chris Wilson
2013-12-17 18:57       ` Chris Wilson
2013-12-18  0:14       ` Keith Packard [this message]
2013-12-18  0:14         ` Keith Packard

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