From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932478AbbIDNJR (ORCPT ); Fri, 4 Sep 2015 09:09:17 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49852 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759387AbbIDNJE (ORCPT ); Fri, 4 Sep 2015 09:09:04 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Chris Wilson , =?UTF-8?q?Micha=C5=82=20Winiarski?= , Daniel Vetter , Luis Henriques Subject: [PATCH 3.16.y-ckt 017/130] drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop Date: Fri, 4 Sep 2015 14:06:45 +0100 Message-Id: <1441372118-5933-18-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1441372118-5933-1-git-send-email-luis.henriques@canonical.com> References: <1441372118-5933-1-git-send-email-luis.henriques@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson commit ee0a227b7ac6e75f28e10269f81c7ec6eb600952 upstream. Since we may conceivably encounter situations where the upper part of the 64bit register changes between reads, for example when a timestamp counter overflows, change the WARN into a retry loop. Signed-off-by: Chris Wilson Cc: Michał Winiarski Signed-off-by: Daniel Vetter Signed-off-by: Luis Henriques --- drivers/gpu/drm/i915/i915_drv.h | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 28c7afdfffbc..67f72fa5a769 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2682,15 +2682,14 @@ int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val); #define I915_READ64(reg) dev_priv->uncore.funcs.mmio_readq(dev_priv, (reg), true) #define I915_READ64_2x32(lower_reg, upper_reg) ({ \ - u32 upper = I915_READ(upper_reg); \ - u32 lower = I915_READ(lower_reg); \ - u32 tmp = I915_READ(upper_reg); \ - if (upper != tmp) { \ - upper = tmp; \ - lower = I915_READ(lower_reg); \ - WARN_ON(I915_READ(upper_reg) != upper); \ - } \ - (u64)upper << 32 | lower; }) + u32 upper, lower, tmp; \ + tmp = I915_READ(upper_reg); \ + do { \ + upper = tmp; \ + lower = I915_READ(lower_reg); \ + tmp = I915_READ(upper_reg); \ + } while (upper != tmp); \ + (u64)upper << 32 | lower; }) #define POSTING_READ(reg) (void)I915_READ_NOTRACE(reg) #define POSTING_READ16(reg) (void)I915_READ16_NOTRACE(reg)