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 1DD30C001E0 for ; Mon, 23 Oct 2023 07:47:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6946B10E16E; Mon, 23 Oct 2023 07:47:16 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5764510E16A for ; Mon, 23 Oct 2023 07:47:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698047233; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=E/xZBjexym1u5u7aqp8YN9N1r+zl4sR8DvaJhc8d5/Q=; b=aJoOS+e1aEDJz6F06+AiUUf5CeBQq89JkvsR4Fr71GxU4uPej+smSWSzT1F4N3Wjxd28J9 xl9OPfGBVlPewlCuxeivG1gqhrlJ8zzXL//1l14CDkjzw3PaJ3+udPRuOdOBWbpMz3BhBR frNmXq0Fse4DO4MkMV8Ts2mjoRZhVhE= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-107-bTJwXCK1NS-XcT0GMFLIfQ-1; Mon, 23 Oct 2023 03:47:07 -0400 X-MC-Unique: bTJwXCK1NS-XcT0GMFLIfQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 84BC21C06E28; Mon, 23 Oct 2023 07:47:06 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.45.225.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id DE89817312; Mon, 23 Oct 2023 07:47:01 +0000 (UTC) From: Albert Esteve To: qemu-devel@nongnu.org Subject: [PATCH v6 9/9] drm: Introduce documentation for hotspot properties Date: Mon, 23 Oct 2023 09:46:13 +0200 Message-ID: <20231023074613.41327-10-aesteve@redhat.com> In-Reply-To: <20231023074613.41327-1-aesteve@redhat.com> References: <20231023074613.41327-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 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: , Cc: linux-doc@vger.kernel.org, banackm@vmware.com, virtualization@lists.linux-foundation.org, Gerd Hoffmann , mombasawalam@vmware.com, iforbes@vmware.com, Jonathan Corbet , javierm@redhat.com, VMware Graphics Reviewers , David Airlie , Maxime Ripard , Hans de Goede , ppaalanen@gmail.com, dri-devel@lists.freedesktop.org, spice-devel@lists.freedesktop.org, Gurchetan Singh , Matt Roper , linux-kernel@vger.kernel.org, krastevm@vmware.com, Thomas Zimmermann Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Michael Banack To clarify the intent and reasoning behind the hotspot properties introduce userspace documentation that goes over cursor handling in para-virtualized environments. The documentation is generic enough to not special case for any specific hypervisor and should apply equally to all. Signed-off-by: Zack Rusin --- Documentation/gpu/drm-kms.rst | 6 ++++ drivers/gpu/drm/drm_plane.c | 58 ++++++++++++++++++++++++++++++++++- 2 files changed, 63 insertions(+), 1 deletion(-) diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index a0c83fc481264..158cdcc9351f9 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -577,6 +577,12 @@ Variable Refresh Properties .. kernel-doc:: drivers/gpu/drm/drm_connector.c :doc: Variable refresh properties +Cursor Hotspot Properties +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_plane.c + :doc: hotspot properties + Existing KMS Properties ----------------------- diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 1dc00ad4c33c3..f3f2eae83cca8 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -230,6 +230,61 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane return 0; } +/** + * DOC: hotspot properties + * + * HOTSPOT_X: property to set mouse hotspot x offset. + * HOTSPOT_Y: property to set mouse hotspot y offset. + * + * When the plane is being used as a cursor image to display a mouse pointer, + * the "hotspot" is the offset within the cursor image where mouse events + * are expected to go. + * + * Positive values move the hotspot from the top-left corner of the cursor + * plane towards the right and bottom. + * + * Most display drivers do not need this information because the + * hotspot is not actually connected to anything visible on screen. + * However, this is necessary for display drivers like the para-virtualized + * drivers (eg qxl, vbox, virtio, vmwgfx), that are attached to a user console + * with a mouse pointer. Since these consoles are often being remoted over a + * network, they would otherwise have to wait to display the pointer movement to + * the user until a full network round-trip has occurred. New mouse events have + * to be sent from the user's console, over the network to the virtual input + * devices, forwarded to the desktop for processing, and then the cursor plane's + * position can be updated and sent back to the user's console over the network. + * Instead, with the hotspot information, the console can anticipate the new + * location, and draw the mouse cursor there before the confirmation comes in. + * To do that correctly, the user's console must be able predict how the + * desktop will process mouse events, which normally requires the desktop's + * mouse topology information, ie where each CRTC sits in the mouse coordinate + * space. This is typically sent to the para-virtualized drivers using some + * driver-specific method, and the driver then forwards it to the console by + * way of the virtual display device or hypervisor. + * + * The assumption is generally made that there is only one cursor plane being + * used this way at a time, and that the desktop is feeding all mouse devices + * into the same global pointer. Para-virtualized drivers that require this + * should only be exposing a single cursor plane, or find some other way + * to coordinate with a userspace desktop that supports multiple pointers. + * If the hotspot properties are set, the cursor plane is therefore assumed to be + * used only for displaying a mouse cursor image, and the position of the combined + * cursor plane + offset can therefore be used for coordinating with input from a + * mouse device. + * + * The cursor will then be drawn either at the location of the plane in the CRTC + * console, or as a free-floating cursor plane on the user's console + * corresponding to their desktop mouse position. + * + * DRM clients which would like to work correctly on drivers which expose + * hotspot properties should advertise DRM_CLIENT_CAP_CURSOR_PLANE_HOTSPOT. + * Setting this property on drivers which do not special case + * cursor planes will return EOPNOTSUPP, which can be used by userspace to + * gauge requirements of the hardware/drivers they're running on. Advertising + * DRM_CLIENT_CAP_CURSOR_PLANE_HOTSPOT implies that the userspace client will be + * correctly setting the hotspot properties. + */ + /** * drm_plane_create_hotspot_properties - creates the mouse hotspot * properties and attaches them to the given cursor plane @@ -237,7 +292,8 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane * @plane: drm cursor plane * * This function enables the mouse hotspot property on a given - * cursor plane. + * cursor plane. Look at the documentation for hotspot properties + * to get a better understanding for what they're used for. * * RETURNS: * Zero for success or -errno -- 2.41.0