From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3834C2D73BC for ; Wed, 1 Apr 2026 12:18:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775045886; cv=pass; b=Oh6vjN9K7N8jB4jd+6VmoiHtvS6ACnft/qPRGNdduYQTgelmzKP4FROaQX9Omn+eQtixo806m371hpF2y9z2RxqgJxTn+0wlqNGY3oO7z3S00KOiKt7hauw4jiFG7SGht6A+S0njxtiRHIDC9h13qIQMLHB18yNS8zgghPBg9f8= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775045886; c=relaxed/simple; bh=P1yzacvLUkrEigtV6ZpE5C0T8rHIaXKp1Bon9OV4CFk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=iWcScFC922OIQNa/hvPNSAVCzvKwEPDol8posx79d48noCNrzHtb+JttGGpOmELdTM73XgJ/oXvFZJUZcEFTXDZa3ETnOaOrVuBXO/t3sCnwMWSN19eW3rZ0WIBL3beSvsOJMngGLsJ5OLQbCm4kRWMJRsri3kaKHrY8MH+02tY= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=nicolas.frattaroli@collabora.com header.b=Nxt0+cq6; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=nicolas.frattaroli@collabora.com header.b="Nxt0+cq6" ARC-Seal: i=1; a=rsa-sha256; t=1775045868; cv=none; d=zohomail.com; s=zohoarc; b=H1BQJNJAvj1eSES0MQZ9UUdZ9ccmZ6tj/Du8W8KG3vLP/lWvBcL4euPlw85GSb+5i+xQ8xslLM9KS+EVKk1teZ/IKvLBAN1cBOED+pbE9zqIuvxsufHDsR7CWSSJbQIfZfBwQtErGUbWnY26mMzuHjnw9YZSf4+kpNGwZ6F6KQU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1775045868; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=TJw/CfjLzcxAm0bwEh1CoqJ4c/lgYdwpRSlmJHfE8G4=; b=aCYLIKfDg53kTBR63ZNm9bcs66Bs9tIfGPuc2WuTfQ++NI+85+IMw/Tdn6eJbB2ZOGQs1oI7C4Sqn5bYCjGFW9rTEhz8GZtVfazqEZtyADFoojtO7J9UMlsVdeOfqNCh4MvneL53l1+BIozvgLBFjGwiXBuqnq0oARhA4g6/GQQ= 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=1775045868; s=zohomail; d=collabora.com; i=nicolas.frattaroli@collabora.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Content-Type:Message-Id:Reply-To; bh=TJw/CfjLzcxAm0bwEh1CoqJ4c/lgYdwpRSlmJHfE8G4=; b=Nxt0+cq69CXIGx4R6KzZm74ISy3GRmpkRhHKSPlyG63YpTkvoyQtN6/T43xU6YOs K7/9ljK17RZsFmiARbznv62BB8EEl75+48gDkU0NcArJJ6rr998NuKWIVCBa7R/r0MU kKD0Gf0kvrO/2i6O9NFn5lZM5qSUVixCk20J5Eb4= Received: by mx.zohomail.com with SMTPS id 1775045867079379.81221661362736; Wed, 1 Apr 2026 05:17:47 -0700 (PDT) From: Nicolas Frattaroli To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Ville =?UTF-8?B?U3lyasOkbMOk?= , Daniel Stone , Dmitry Baryshkov Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, Derek Foreman , Marius Vlad Subject: Re: [PATCH v6 0/2] Add "link bpc" DRM property Date: Wed, 01 Apr 2026 14:17:41 +0200 Message-ID: <4517017.tdWV9SEqCh@workhorse> In-Reply-To: <20260330-link-bpc-v6-0-ff124af93e48@collabora.com> References: <20260330-link-bpc-v6-0-ff124af93e48@collabora.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" On Monday, 30 March 2026 10:33:08 Central European Summer Time Nicolas Frattaroli wrote: > This series adds a new "link bpc" DRM property. It reflects the display > link's actual achieved output bits per component, considering any > degradation of the bit depth done by drivers for bandwidth or other > reasons. The property's value is updated during an atomic commit, which > is also when it fires an uevent if it changed to let userspace know. > > There's a weston implementation at [1] which makes use of this new > property. It is not representative of the entire use case of the > property, but rather a proof-of-concept. > > [1]: https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1850 > > --- > Changes in v6: > - Drop amdgpu patch to unblock series. > - Reword property documentation to make it more explicit as to what bits > this counts and why someone would want this. > - Reword first patch message to do the same. > - Link to v5: https://lore.kernel.org/r/20260319-link-bpc-v5-0-5306cd04a708@collabora.com > > Changes in v5: > - Split "drm/connector: hdmi: Add a 'link bpc' property" into two > patches; one adding the property, the other making use for it in the > HDMI helpers (Maxime) > - Apply Maxime's Ack to the two split patches as per the review > - Link to v4: https://lore.kernel.org/r/20260311-link-bpc-v4-0-51775e964720@collabora.com > > Changes in v4: > - Throw out the workqueue and delayed work item > - Remove the drm_connector_update_link_bpc_state function > - Reimplement it by updating the property and firing the uevent in > commit_tail > - Check that the provided max_bpc value in attach_link_bpc_property is > within the expected range > - Clamp the connector state's link_bpc value between 8 and max_bpc so > that no value outside the declared range is ever written to the drm > property > - Update and reword doc strings > - Add an amdgpu implementation > - Link to v3: https://lore.kernel.org/r/20251022162843.1759-1-marius.vlad@collabora.com/T/ > > Changes in v3: > - remove VRR mention from commit description (Ville) > - add DRM_MODE_PROP_IMMUTABLE to flags (Ville) > - provide helpers functions for drivers to use (can be used by other > types of connectors, not just HDMI) > - send uevent informating userspace when 'link bpc' connector state > changed (Daniel @ https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1850) > - added missing doc entry > - Link to v2: https://lore.kernel.org/r/20251006083043.3115-1-marius.vlad@collabora.com/T/ > > Changes in v2: > - replace return with EBUSY if connector already exists (Dmitry) > - add i-g-t test and an implementation for Weston (Dmitry) > - re-wording patch description (Jani) > - Link to v1: https://lore.kernel.org/r/20250801101750.1726-1-marius.vlad@collabora.com/T/ > > Signed-off-by: Nicolas Frattaroli > > --- > Nicolas Frattaroli (2): > drm/connector: Add a 'link bpc' property > drm/connector: hdmi: Add support for 'link bpc' property > > drivers/gpu/drm/display/drm_hdmi_state_helper.c | 2 + > drivers/gpu/drm/drm_atomic_helper.c | 9 +++ > drivers/gpu/drm/drm_atomic_uapi.c | 2 + > drivers/gpu/drm/drm_connector.c | 88 +++++++++++++++++++++++++ > include/drm/drm_connector.h | 16 +++++ > 5 files changed, 117 insertions(+) > --- > base-commit: 3a48a999a2e3c3d1988d44370ed8f43ff54700b6 > change-id: 20260309-link-bpc-d0afc475ac49 > > Best regards, > -- > Nicolas Frattaroli > > There's a lot of unresolved discussion on v5 of the series going on at the moment, so please don't merge v6 despite the acks, there will likely be a v7. Kind regards, Nicolas Frattaroli