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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2F11DCA5FD4 for ; Fri, 2 Oct 2026 09:28:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 91D3E10F813; Fri, 2 Oct 2026 09:28:33 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="WVhrEdIh"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id E1DA610F81B; Fri, 2 Oct 2026 09:28:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790933313; x=1822469313; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=sxgt4svY/TgU/8j1VAh62BCWuhGx/pOZGibuvtoS9gk=; b=WVhrEdIheFtNDH/ZlaZ2WCxXhH7K4B4NKvhhgzYd/UctG970vSRTI1u7 wEA639CYzlR2KhhZk+Km+fg9qeJ9Pzv6R3uzGwUzaGehYawD98L5/3o8s kikvG/uVTX6Gx1x/7aeDFgnaVh03YbU68yTN6eiiIPZ3LRKaBg7ww9pKP H8TWQkgXrLMGjhYBzIBAABpJLLTQrVd3ZK+TSD09CvWGBY3+r1xWWDc5Y DfFuK3/2piuiC3w3D8ArxVUkvyerdd4o1tEWd7TXFmo2QOsw4pY1W2hX1 h/ZFNQbuily2DCHhQi60Ef5dD2YOqaFUKSfRUjYlwwVVMQ5PwqEudYmTM Q==; X-CSE-ConnectionGUID: umQwfF0vQImfr0+2Pv2MNQ== X-CSE-MsgGUID: mfnOQ11ER8mjVGFREVK6CA== X-IronPort-AV: E=McAfee;i="6800,10657,11922"; a="94410617" X-IronPort-AV: E=Sophos;i="6.27,136,1787036400"; d="scan'208";a="94410617" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2026 02:28:32 -0700 X-CSE-ConnectionGUID: FSPQd3BKQ9+5htSjEiZsUA== X-CSE-MsgGUID: NSsIUt+PTVS3mdFueRNvJg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,136,1787036400"; d="scan'208";a="275762357" Received: from slindbla-desk.ger.corp.intel.com (HELO localhost) ([10.245.244.196]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2026 02:28:31 -0700 From: Jani Nikula To: FNU VISHWANATHA , dri-devel@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org, FNU VISHWANATHA Subject: Re: [PATCH 2/2] drm/i915/mst: Force link address reprobe after MST resume In-Reply-To: <44a15723fd2b9a9152c382dcf8df86e51bfabbe3@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland References: <20261001215705.3891147-1-fnu.vishwanatha@intel.com> <20261001215705.3891147-2-fnu.vishwanatha@intel.com> <44a15723fd2b9a9152c382dcf8df86e51bfabbe3@intel.com> Date: Fri, 02 Oct 2026 12:28:27 +0300 Message-ID: <0c60e374cfbeef12abf349b0750de5df8f4f1b9a@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 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" On Fri, 02 Oct 2026, Jani Nikula wrote: > On Thu, 01 Oct 2026, FNU VISHWANATHA wrote: >> After resume from warm boot/G3, immediately force a topology link address >> reprobe to ensure all MST ports are properly detected. This works around a >> race condition where some MST hubs incorrectly report port status bits before >> their internal state is fully initialized. >> >> By forcing the reprobe immediately after resume, combined with the fix in >> drm_dp_mst_handle_link_address_port() that detects input->output port >> transitions, we ensure that all displays are reliably detected even if the >> hub initially reports incorrect port status. >> >> Signed-off-by: FNU VISHWANATHA > > Is there a bug report about this with logs? > >> --- >> drivers/gpu/drm/i915/display/intel_dp.c | 18 ++++++++++++++++++ >> 1 file changed, 18 insertions(+) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c >> index 3a67990411b3..fceda523efa3 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dp.c >> +++ b/drivers/gpu/drm/i915/display/intel_dp.c >> @@ -7088,6 +7088,7 @@ void intel_dp_mst_resume(struct intel_display *display) >> >> for_each_intel_encoder(display->drm, encoder) { >> struct intel_dp *intel_dp; >> + struct drm_dp_mst_branch *mstb; >> int ret; >> >> if (encoder->type != INTEL_OUTPUT_DDI) >> @@ -7102,6 +7103,23 @@ void intel_dp_mst_resume(struct intel_display *display) >> if (ret) { >> intel_dp->is_mst = false; >> drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst.mgr, false); >> + continue; >> + } >> + >> + /* After resume, force a link address reprobe to ensure all ports >> + * are properly detected. This works around a race condition where >> + * some MST hubs incorrectly report port status bits during warm boot/G3. >> + * Ref: Sporadic second display not detected after warm boot/G3 >> + */ >> + if (intel_dp->is_mst) { >> + mutex_lock(&intel_dp->mst.mgr.lock); >> + mstb = intel_dp->mst.mgr.mst_primary; >> + if (mstb) { >> + drm_dp_mst_topology_get_mstb(mstb); >> + mstb->link_address_sent = false; >> + drm_dp_mst_topology_put_mstb(mstb); >> + } >> + mutex_unlock(&intel_dp->mst.mgr.lock); This is topology manager internal stuff we have no business messing with in drivers. So much so that drm_dp_mst_topology_get_mstb() and drm_dp_mst_topology_put_mstb() are *static* functions in drm_dp_mst_topology.c. How did you build and run this? >> } >> } >> } -- Jani Nikula, Intel