From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756743AbcEXSJ4 (ORCPT ); Tue, 24 May 2016 14:09:56 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:37841 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964956AbcEXRzr (ORCPT ); Tue, 24 May 2016 13:55:47 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Arindam Nath , Alex Deucher , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 09/53] drm/radeon: fix DP link training issue with second 4K monitor Date: Tue, 24 May 2016 10:54:39 -0700 Message-Id: <1464112523-3701-10-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1464112523-3701-1-git-send-email-kamal@canonical.com> References: <1464112523-3701-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt11 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Arindam Nath commit 1a738347df2ee4977459a8776fe2c62196bdcb1b upstream. There is an issue observed when we hotplug a second DP 4K monitor to the system. Sometimes, the link training fails for the second monitor after HPD interrupt generation. The issue happens when some queued or deferred transactions are already present on the AUX channel when we initiate a new transcation to (say) get DPCD or during link training. We set AUX_IGNORE_HPD_DISCON bit in the AUX_CONTROL register so that we can ignore any such deferred transactions when a new AUX transaction is initiated. Signed-off-by: Arindam Nath Reviewed-by: Alex Deucher Signed-off-by: Alex Deucher Signed-off-by: Kamal Mostafa --- drivers/gpu/drm/radeon/radeon_dp_auxch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/radeon/radeon_dp_auxch.c b/drivers/gpu/drm/radeon/radeon_dp_auxch.c index 3b0c229..db64e00 100644 --- a/drivers/gpu/drm/radeon/radeon_dp_auxch.c +++ b/drivers/gpu/drm/radeon/radeon_dp_auxch.c @@ -105,7 +105,7 @@ radeon_dp_aux_transfer_native(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg tmp &= AUX_HPD_SEL(0x7); tmp |= AUX_HPD_SEL(chan->rec.hpd); - tmp |= AUX_EN | AUX_LS_READ_EN; + tmp |= AUX_EN | AUX_LS_READ_EN | AUX_HPD_DISCON(0x1); WREG32(AUX_CONTROL + aux_offset[instance], tmp); -- 2.7.4