From: Chris Wilson <chris@chris-wilson.co.uk>
To: Keith Packard <keithp@keithp.com>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915/crt: Remove 0xa0 probe for CRT
Date: Mon, 04 Apr 2011 16:29:55 +0100 [thread overview]
Message-ID: <849307$cab831@azsmga001.ch.intel.com> (raw)
In-Reply-To: <yunipuuawav.fsf@aiko.keithp.com>
On Mon, 04 Apr 2011 08:08:40 -0700, Keith Packard <keithp@keithp.com> wrote:
> On Mon, 4 Apr 2011 07:26:44 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>
> > Following the fix to reset the GMBUS controller after a NAK, we finally
> > utilize the 0xa0 probe for a CRT connection. And discover that it is
> > useless as it simply detects the presence of the controller and not the
> > actual monitor. Given that we already probe 0x50 prior to performing the
> > EDID retrieval, we can simply remove the redundant probe to 0xa0.
>
> I don't understand -- are you saying that there is additional hardware
> somewhere in the machine responding to I2C transactions on the monitor's
> DDC bus?
Yes. I'm saying that that the controller accepts a write to port 0xa0.
> And if so, how was this extra transaction breaking things? The GMBUS
> reset patch should only have an effect when there are failed
> transactions, not successful ones, and then it should only cause future
> transactions to fail, not succeed. Besides, the 0xA0 transaction looks
> like the first one on the bus.
We do several i2c xfers before CRT.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
next prev parent reply other threads:[~2011-04-04 15:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-04 6:26 [PATCH 1/2] drm/i915/crt: Remove 0xa0 probe for CRT Chris Wilson
2011-04-04 6:26 ` [PATCH 2/2] drm/i915/crt: Explicitly return false if connected to a digital monitor Chris Wilson
2011-04-04 15:09 ` Keith Packard
2011-04-04 15:25 ` Chris Wilson
2011-04-04 16:27 ` Keith Packard
2011-04-04 15:08 ` [PATCH 1/2] drm/i915/crt: Remove 0xa0 probe for CRT Keith Packard
2011-04-04 15:29 ` Chris Wilson [this message]
2011-04-04 16:26 ` Keith Packard
2011-04-05 0:19 ` Dave Airlie
2011-04-05 1:04 ` Keith Packard
2011-04-05 9:18 ` Chris Wilson
2011-04-05 1:57 ` Keith Packard
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