From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFD8EC43441 for ; Mon, 19 Nov 2018 16:39:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7EE021104 for ; Mon, 19 Nov 2018 16:39:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="OsacfuXl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7EE021104 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732738AbeKTDDc (ORCPT ); Mon, 19 Nov 2018 22:03:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:36172 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731810AbeKTDDa (ORCPT ); Mon, 19 Nov 2018 22:03:30 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A34222145D; Mon, 19 Nov 2018 16:39:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542645561; bh=4B5gurcMpRQe0iMG1k4DlM8GAmOtACbsd7aFz/aP91I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OsacfuXlQjT2DmJv4+lRwdwhcH63eEy5pNoqnLt5E1Df5IuhgRpgcVEPYdb7rA/e5 URCkfPWvR744O5llQcMjQZlwVMKsfYwzc8VD6Vp706HP8oY9Gz0mSuJ8lZxOVzOPw+ M7u6vqDQlhC5xtg0F3WVT08P3A2BJRr8bHxCzH1k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lyude Paul , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Jani Nikula , Rodrigo Vivi , Jan-Marek Glogowski , Dhinakaran Pandiyan , Joonas Lahtinen Subject: [PATCH 4.19 190/205] drm/i915/dp: Fix link retraining comment in intel_dp_long_pulse() Date: Mon, 19 Nov 2018 17:28:17 +0100 Message-Id: <20181119162641.926279322@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181119162616.586062722@linuxfoundation.org> References: <20181119162616.586062722@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dhinakaran Pandiyan commit 49af5d95b9b3c21a84ad115a9db9acbc036d849a upstream. Comment claims link needs to be retrained because the connected sink raised a long pulse to indicate link loss. If the sink did so, intel_dp_hotplug() would have handled link retraining. Looking at the logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-apply Perform link quality check, unconditionally during long pulse"")', the issue is that the sink does not trigger an interrupt. What we want is ->detect() from user space to check link status and retrain. Ville's review for the original patch also indicates the same root cause. So, rewrite the comment. v2: Patch split and rewrote comment. Cc: Lyude Paul Cc: Ville Syrjälä Cc: Jani Nikula Cc: Rodrigo Vivi Cc: Jan-Marek Glogowski References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") Signed-off-by: Dhinakaran Pandiyan Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20180927205735.16651-1-dhinakaran.pandiyan@intel.com (cherry picked from commit 9ebd8202393dde9d3678c9ec162c1aa63ba17eac) Fixes: 399334708b4f ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") Cc: stable@vger.kernel.org Signed-off-by: Joonas Lahtinen Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/intel_dp.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4741,16 +4741,9 @@ intel_dp_long_pulse(struct intel_connect goto out; } else { /* - * If display is now connected check links status, - * there has been known issues of link loss triggering - * long pulse. - * - * Some sinks (eg. ASUS PB287Q) seem to perform some - * weird HPD ping pong during modesets. So we can apparently - * end up with HPD going low during a modeset, and then - * going back up soon after. And once that happens we must - * retrain the link to get a picture. That's in case no - * userspace component reacted to intermittent HPD dip. + * Some external monitors do not signal loss of link + * synchronization with an IRQ_HPD, so force a link status + * check. */ struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;