From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [PATCH 09/13 v4] drm/i915/intel_i2c: use double-buffered writes
Date: Tue, 27 Mar 2012 19:45:22 +0100
Message-ID: <1332873931_116908@CP5-2952>
References: <1332873382-29373-1-git-send-email-djkurtz@chromium.org> <1332873382-29373-10-git-send-email-djkurtz@chromium.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1332873382-29373-10-git-send-email-djkurtz@chromium.org>
Sender: linux-kernel-owner@vger.kernel.org
To: Daniel Vetter <daniel@ffwll.ch>, Keith Packard <keithp@keithp.com>, David Airlie <airlied@linux.ie>, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc: Benson Leung <bleung@chromium.org>, Yufeng Shen <miletus@chromium.org>, Daniel Kurtz <djkurtz@chromium.org>
List-Id: dri-devel@lists.freedesktop.org

On Wed, 28 Mar 2012 02:36:18 +0800, Daniel Kurtz <djkurtz@chromium.org> wrote:
> @@ -276,6 +269,13 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
>  
>  		I915_WRITE(GMBUS3 + reg_offset, val);
>  		POSTING_READ(GMBUS2 + reg_offset);

You might as well squash this posting read as the write flush is
redundant given the following read of GMBUS2.

> +
> +		if (wait_for(I915_READ(GMBUS2 + reg_offset) &
> +			     (GMBUS_SATOER | GMBUS_HW_RDY),
> +			     50))
> +			return -ETIMEDOUT;
> +		if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
> +			return -ENXIO;

-- 
Chris Wilson, Intel Open Source Technology Centre