From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757716Ab2C1NFe (ORCPT ); Wed, 28 Mar 2012 09:05:34 -0400 Received: from smtp.fireflyinternet.com ([109.228.6.236]:6286 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757220Ab2C1NFd (ORCPT ); Wed, 28 Mar 2012 09:05:33 -0400 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.66.37; From: Chris Wilson Subject: Re: [PATCH 14/14 v5] drm/i915/intel_i2c: remove POSTING_READ() from gmbus transfers To: Daniel Kurtz , Daniel Vetter , Keith Packard , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Benson Leung , Yufeng Shen , Daniel Kurtz In-Reply-To: <1332939117-6513-15-git-send-email-djkurtz@chromium.org> References: <1332939117-6513-1-git-send-email-djkurtz@chromium.org> <1332939117-6513-15-git-send-email-djkurtz@chromium.org> Date: Wed, 28 Mar 2012 14:05:13 +0100 X-Originating-IP: 78.156.66.37 Message-ID: <1332939924_127442@CP5-2952> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 28 Mar 2012 20:51:57 +0800, Daniel Kurtz wrote: > The POSTING_READ() calls were originally added to make sure the writes > were flushed before any timing delays and across loops. > However, the normal I915_READ() and I915_WRITE() macros already call > readl() / writel(), which already have an explicit mb(). > > Now that the code has settled a bit, let's remove them. > > Signed-off-by: Daniel Kurtz > --- > drivers/gpu/drm/i915/intel_i2c.c | 5 ----- > 1 files changed, 0 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c > index 2865313..be2852e 100644 > --- a/drivers/gpu/drm/i915/intel_i2c.c > +++ b/drivers/gpu/drm/i915/intel_i2c.c > @@ -131,7 +131,6 @@ static void set_clock(void *data, int state_high) > GPIO_CLOCK_VAL_MASK; > > I915_WRITE_NOTRACE(bus->gpio_reg, reserved | clock_bits); > - POSTING_READ(bus->gpio_reg); We do need the write flush here (and set_data) as the next action is a udelay loop which is not per-se a mb. -Chris -- Chris Wilson, Intel Open Source Technology Centre