From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:41893 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752999AbbH0Pj5 (ORCPT ); Thu, 27 Aug 2015 11:39:57 -0400 From: Sasha Levin To: stable@vger.kernel.org, stable-commits@vger.kernel.org Cc: Chris Wilson , =?UTF-8?q?Micha=C5=82=20Winiarski?= , Daniel Vetter , Sasha Levin Subject: [added to the 3.18 stable tree] drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop Date: Thu, 27 Aug 2015 11:37:26 -0400 Message-Id: <1440689954-10813-8-git-send-email-sasha.levin@oracle.com> In-Reply-To: <1440689954-10813-1-git-send-email-sasha.levin@oracle.com> References: <1440689954-10813-1-git-send-email-sasha.levin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: From: Chris Wilson This patch has been added to the 3.18 stable tree. If you have any objections, please let us know. =============== [ Upstream commit ee0a227b7ac6e75f28e10269f81c7ec6eb600952 ] 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 Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Signed-off-by: Sasha Levin --- 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 a849713..c68e9f2 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2899,15 +2899,14 @@ 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) -- 2.1.4