From patchwork Thu Sep 27 20:57:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Dhinakaran Pandiyan X-Patchwork-Id: 10618555 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A603515A6 for ; Thu, 27 Sep 2018 20:57:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 989482B94D for ; Thu, 27 Sep 2018 20:57:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8CB5A2B95D; Thu, 27 Sep 2018 20:57:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 442972B94D for ; Thu, 27 Sep 2018 20:57:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F11366E625; Thu, 27 Sep 2018 20:57:43 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3986C6E062 for ; Thu, 27 Sep 2018 20:57:42 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Sep 2018 13:57:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,312,1534834800"; d="scan'208";a="266496577" Received: from dk-thinkpad-x260.jf.intel.com (HELO dk-ThinkPad-X260.fios-router.home) ([10.54.75.54]) by fmsmga005.fm.intel.com with ESMTP; 27 Sep 2018 13:57:41 -0700 From: Dhinakaran Pandiyan To: intel-gfx@lists.freedesktop.org Date: Thu, 27 Sep 2018 13:57:30 -0700 Message-Id: <20180927205735.16651-1-dhinakaran.pandiyan@intel.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Subject: [Intel-gfx] [CI 1/6] drm/i915/dp: Fix link retraining comment in intel_dp_long_pulse() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP 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 --- drivers/gpu/drm/i915/intel_dp.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 256a71c8c093..207b3ea2ed1a 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -5074,16 +5074,9 @@ intel_dp_long_pulse(struct intel_connector *connector, 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;