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 5BFF1FA1FE1 for ; Wed, 22 Apr 2026 18:24:47 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 70E3610E08E; Wed, 22 Apr 2026 18:24:46 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=collabora.com header.i=nicolas.frattaroli@collabora.com header.b="ROn2zXPo"; dkim-atps=neutral Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) by gabe.freedesktop.org (Postfix) with ESMTPS id 277BF10E08E; Wed, 22 Apr 2026 18:24:45 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; t=1776882272; cv=none; d=zohomail.com; s=zohoarc; b=dLEa9x4IS9TjivUY7VPYnkO1F3Yu6KnjmTrJmjp0ldYQTYqwRqWt5uFHjSHDvOpE6TZCgpEr5B4m2zijFKVo6s1c6pXFIaiVbJMGYnHHXYxohXNt51uW7RZLqwZJUP6aqOytBAl+J2g3rqjvCw4REU5WCUR1/tnvLfGCsb1uZpI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1776882272; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=mEk38yepoHA8K74NovTtgivPyLiqXKjReVl++qj9Aak=; b=bU//KzT7PBmR64a4OtXn2qknzjyb41mXn4zyOAxQrwc7pVJM/88hYfMCLoES76j3DuWFQTJld4D8WVHFHY4uOW6ClWGAmMyzufSWRUZ8vQbEDBTdWWE9GM0fzvAetDDzZk6p2+5uPz+mnZOZBOra8RYYBmmjuMy4gfmjnCwgmn4= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=nicolas.frattaroli@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1776882272; s=zohomail; d=collabora.com; i=nicolas.frattaroli@collabora.com; h=From:From:Subject:Subject:Date:Date:Message-Id:Message-Id:MIME-Version:Content-Type:Content-Transfer-Encoding:To:To:Cc:Cc:Reply-To; bh=mEk38yepoHA8K74NovTtgivPyLiqXKjReVl++qj9Aak=; b=ROn2zXPoy7x+RdnJHTi0PqAMc/Fezp56Bm1v74rbJiDcJPApkl33fcWh4fb46uxW 7zCnnZYatt5AI3SEtNMWZBVhkRBTsEXwCOXWL823i1z4Py/EDE3diba6/O3TvdawX7X OLrhK2M8henqeUveUUdV8gtxDGqHjJLbF93aGt50= Received: by mx.zohomail.com with SMTPS id 1776882269764220.28331060882078; Wed, 22 Apr 2026 11:24:29 -0700 (PDT) From: Nicolas Frattaroli Subject: [PATCH v9 0/2] Pass down hot-plug CONNECTOR ID to user-space Date: Wed, 22 Apr 2026 20:24:06 +0200 Message-Id: <20260422-hot-plug-passup-v9-0-aef804255986@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/22PwW6DMBBEfwX5XFN2wQZy6n9UPazBDpYgJjagV hH/XkNTRQrZy2pkz5udGwvaWx3YKbkxrxcbrLtEUb8lrOnoctbctlEzzFBmgMA7N/Gxn898pBD mkZtKt1luyib+YNE1em3s9078/IraeDfwqfOa/jkCtpGY51UKAgrgwAfydg7p0lP70bi+J+U8p Y0b7kivr3O8bfrjMkVB8/g62OmUtD4G2PH9vtmW2tkwOf+z11rk7rk3yA8NFskzTkRGQlvLTKm nCzbeUj4YCOWRUUaGqRBBIZEScGyxewsQr701YamN0Fhg9Sq/euQXiEdGFRmiMaSlogKgfmas6 /oLKTnVMuwBAAA= X-Change-ID: 20260121-hot-plug-passup-f8ed03f7c202 To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Stanislav Lisovskiy , =?utf-8?q?Ville_Syrj=C3=A4l=C3=A4?= , Louis Chauvet , Haneen Mohammed , Melissa Wen , Daniel Stone , Ian Forbes , Dmitry Baryshkov Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, kernel@collabora.com, wayland-devel@lists.freedesktop.org, Nicolas Frattaroli , Marius Vlad X-Mailer: b4 0.15.2 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This series addresses a shortcoming whereby a hot plug event is sent without it being passed the actual connector that caused it. This takes into consideration both the polling path and the HPD (Hot Plug Detect) path. The motivation is that user-space applications such as Weston would previously receive non-connector-specific hotplug events, and then have to figure out themselves which connector needs to have a modeset executed on. This notably did not work when the hotplug events came in too fast, resulting in Weston missing an on-off-on transition of a connector, seeing that its state was unchanged from "on" so can't be the one that was hotplugged, and skipping reinitialising it as it looks through the other connectors that could've caused it. The real world implication is that on setups with slightly sketchy HDMI connections, a brief flicker in the HPD signal could result in video output bidding farewell entirely until a manual proper re-plug was performed. By sending connector specific hotplug events, this ambiguity is resolved without any change to the user-space API. Future work should however make the kernel explicitly request a modeset from userspace through a more robust path, either by using link-status (nb. the userspace side may not handle it properly at present) or by exposing the epoch counter through the uAPI such that fragile state comparison code is no longer needed. This change results in potentially more hotplug events being sent than previously, as n changed connectors at a time result in n hotplug events, rather than just a single one. Signed-off-by: Nicolas Frattaroli --- Changes in v9: - Get rid of the kmalloc_array by splitting the hotplug event into its two constituent parts to avoid the deadlock. - Link to v8: https://patch.msgid.link/20260422-hot-plug-passup-v8-0-5cfae6ba4119@collabora.com Changes in v8: - Drop pending_hp patch - Add patch correcting epoch_counter documentation - Rework implementation such that hotplug events are still sent outside the mode_config mutex, but don't iterate through the connector list without the lock. - Link to v7: https://patch.msgid.link/20260415-hot-plug-passup-v7-0-9a27ef5e2428@collabora.com Changes in v7 RESEND: - None, other than removing the leftover diffstat from the cover letter - Link to v7: https://lore.kernel.org/r/20260217-hot-plug-passup-v7-0-f8221b2aab51@collabora.com Changes in v7: - Drop the two vkms patches, as I don't want them to be blocked on review. I still think they're correct, but they're not essential and don't need to block this series. - Link to v6: https://lore.kernel.org/r/20260123-hot-plug-passup-v6-0-aaaf61d960bb@collabora.com Changes in v6: - Rewrote cover letter to explain the motivation for this series more plainly - Rename "status_changed" to "pending_hp" - Set "pending_hp" in the existing path that would also affect epoch_counter - No longer set the boolean in drm_helper_probe_single_connector_modes, as it does not appear to be necessary - Reword commits to better justify the changes - Link to v5: https://lore.kernel.org/r/20251111162338.15141-1-marius.vlad@collabora.com/ Changes in v5: - vkms: add support for sending the CONNECTOR ID when hot-plugging through ConfigFS - as reported by Louis, vkms can now make use of ConfigFS to simulate connector status. - vkms: add a small change to ignore previous/old drm connector status when sending out hot-plug uevent. - Link to v4: https://lore.kernel.org/r/20251103174558.7709-1-marius.vlad@collabora.com/ Changes in v4: - removed the "This patch" bit - Dmitry - added a short note when the flag is set and cleared - Dmitry - address double dead-locking detected - kbot: https://lore.kernel.org/dri-devel/202509251410.fdfbcac3-lkp@intel.com/ - virtual connectors do not seem have any kind of hotplug - added polling in vkms - as noted by Ian - Link to v3: https://lore.kernel.org/r/20250923083636.4749-1-marius.vlad@collabora.com/ Changes in v3: - Address comments from Dmitry: - guard connector status write with mode_config.mutex - avoid setting up the connector status and immediately unset it. Do the unset in drm_kms_helper_hotplug_event/drm_kms_helper_connector_hotplug_event - Link to v2: https://lore.kernel.org/r/20250729165708.9947-1-marius.vlad@collabora.com/ Changes in v2: - Address comments from Daniel: - split patch into 2, one that introduces a bool to track connector connection status change and a patch that uses that to be able to send hot plug events with the proper CONNECTOR ID to udev and further pass that down to user-space - nuke out mutex when iterating connector list - fix typo - Link to v1: https://lore.kernel.org/r/20250627131751.2004-1-marius.vlad@collabora.com/ --- Nicolas Frattaroli (2): drm/connector: Fix epoch_counter docs to reflect reality drm: Send per-connector hotplug events drivers/gpu/drm/drm_probe_helper.c | 37 ++++++++++++++++--------------------- include/drm/drm_connector.h | 5 ++++- 2 files changed, 20 insertions(+), 22 deletions(-) --- base-commit: 489e26ada57ce96a2ee3e5853cfe74981ef85bbd change-id: 20260121-hot-plug-passup-f8ed03f7c202 Best regards, -- Nicolas Frattaroli