Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932378AbbG1Jot (ORCPT ); Tue, 28 Jul 2015 05:44:49 -0400 Received: from mail-wi0-f175.google.com ([209.85.212.175]:35167 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932351AbbG1Joq (ORCPT ); Tue, 28 Jul 2015 05:44:46 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jim Bride , Jani Nikula , Jiri Slaby Subject: [PATCH 3.12 021/124] drm/i915/hsw: Fix workaround for server AUX channel clock divisor Date: Tue, 28 Jul 2015 11:42:35 +0200 Message-Id: <1dec7c0ba1c46a8a6008daf90afc05b5805582f1.1438076484.git.jslaby@suse.cz> X-Mailer: git-send-email 2.4.6 In-Reply-To: <90d8a5681e4a9e320611b422f0ed012e148c2bca.1438076484.git.jslaby@suse.cz> References: <90d8a5681e4a9e320611b422f0ed012e148c2bca.1438076484.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1802 Lines: 56 From: Jim Bride 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- 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 b0191f25cd55..5a9ef60ab625 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -394,10 +394,8 @@ 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) { @@ -406,6 +404,7 @@ 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 */ -- 2.4.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/