From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965182AbbGHPtr (ORCPT ); Wed, 8 Jul 2015 11:49:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:47950 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933912AbbGHPlK (ORCPT ); Wed, 8 Jul 2015 11:41:10 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jim Bride , Jani Nikula , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 30/56] drm/i915/hsw: Fix workaround for server AUX channel clock divisor Date: Wed, 8 Jul 2015 08:40:11 -0700 Message-Id: <1436370037-25874-31-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1436370037-25874-1-git-send-email-kamal@canonical.com> References: <1436370037-25874-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt23 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jim Bride commit e058c945e03a629c99606452a6931f632dd28903 upstream. According to the HSW b-spec we need to try clock divisors of 63 and 72, each 3 or more times, when attempting DP AUX channel communication on a server chipset. This actually wasn't happening due to a short-circuit that only checked the DP_AUX_CH_CTL_DONE bit in status rather than checking that the operation was done and that DP_AUX_CH_CTL_TIME_OUT_ERROR was not set. [v2] Implemented alternate solution suggested by Jani Nikula. Signed-off-by: Jim Bride Signed-off-by: Jani Nikula Signed-off-by: Kamal Mostafa --- drivers/gpu/drm/i915/intel_dp.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 6b50a14..4ac4a41 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -481,10 +481,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, DP_AUX_CH_CTL_RECEIVE_ERROR)) continue; if (status & DP_AUX_CH_CTL_DONE) - break; + goto done; } - if (status & DP_AUX_CH_CTL_DONE) - break; } if ((status & DP_AUX_CH_CTL_DONE) == 0) { @@ -493,6 +491,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, goto out; } +done: /* Check for timeout or receive error. * Timeouts occur when the sink is not connected */ -- 1.9.1