From: Keith Packard <keithp@keithp.com>
To: Dave Airlie <airlied@gmail.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915/crt: Remove 0xa0 probe for CRT
Date: Mon, 04 Apr 2011 18:04:35 -0700 [thread overview]
Message-ID: <yun1v1hik4c.fsf@aiko.keithp.com> (raw)
In-Reply-To: <BANLkTik+NFzAww9VHspE2-09_kZU2vAXXQ@mail.gmail.com>
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On Tue, 5 Apr 2011 10:19:16 +1000, Dave Airlie <airlied@gmail.com> wrote:
> On Tue, Apr 5, 2011 at 2:26 AM, Keith Packard <keithp@keithp.com> wrote:
> > On Mon, 04 Apr 2011 16:29:55 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> >
> >> Yes. I'm saying that that the controller accepts a write to port 0xa0.
> >
> > So it's the GMBUS controller itself then, I guess. Weird.
> >
> > Let me see if I understand how it used to work and why fixing the GMBUS
> > reset causes it to break in this case.
> >
>
> I could be missing something here, but aren't i2c addresses 8-bit in this case?
>
> 7-bit addr + direction bit, which means 0xa0 isn't valid i2c address,
> since in Linux
> the read/write bits are specified separately.
Could this be is a mis-translation of some X server code? The X
server stuck the direction bit in the LSB of the I2C address and
required that the drivers shift the register up and add the direction
bit manually (yes, a terrible API).
This is starting to make a lot more sense now. 0xa0 == 0x50 << 1.
--
keith.packard@intel.com
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next prev parent reply other threads:[~2011-04-05 1:04 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
2011-04-04 16:26 ` Keith Packard
2011-04-05 0:19 ` Dave Airlie
2011-04-05 1:04 ` Keith Packard [this message]
2011-04-05 9:18 ` Chris Wilson
2011-04-05 1:57 ` Keith Packard
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