linux-kernel - Re: [PATCH 4/7 v6] drm/i915/intel

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Message-ID: <1332960542_131144@CP5-2952>
Date:	Wed, 28 Mar 2012 19:48:51 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Daniel Kurtz <djkurtz@...omium.org>,
	Daniel Vetter <daniel@...ll.ch>,
	Keith Packard <keithp@...thp.com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:	Benson Leung <bleung@...omium.org>,
	Yufeng Shen <miletus@...omium.org>,
	Daniel Kurtz <djkurtz@...omium.org>
Subject: Re: [PATCH 4/7 v6] drm/i915/intel_i2c: use WAIT cycle, not STOP

On Thu, 29 Mar 2012 02:26:36 +0800, Daniel Kurtz <djkurtz@...omium.org> wrote:
> The i915 is only able to generate a STOP cycle (i.e. finalize an i2c
> transaction) during a DATA or WAIT phase.  In other words, the
> controller rejects a STOP requested as part of the first transaction in a
> sequence.

The original docs have "this can only cause a STOP to be generated if a
GMBUS cycle is generated, the GMBUS is currently in a data phase, or it
is in a WAIT phase."

So from that it seems STOP | INDEX? | WAIT is always a valid
combination and is explicitly listed in the register set.

I defer to actual testing though ;)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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