From patchwork Wed Jul 19 01:42:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zack Rusin X-Patchwork-Id: 13318055 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 27B5DEB64DC for ; Wed, 19 Jul 2023 01:43:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 41F4010E3EC; Wed, 19 Jul 2023 01:43:08 +0000 (UTC) Received: from letterbox.kde.org (letterbox.kde.org [46.43.1.242]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8AE1F10E3F2 for ; Wed, 19 Jul 2023 01:42:40 +0000 (UTC) Received: from vertex.vmware.com (pool-173-49-113-140.phlapa.fios.verizon.net [173.49.113.140]) (Authenticated sender: zack) by letterbox.kde.org (Postfix) with ESMTPSA id 7248A3262B6; Wed, 19 Jul 2023 02:42:38 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kde.org; s=users; t=1689730959; bh=5pvP7ou4tTt9c7uiOWK9JZ2IMgYt+qy5f2CKcoNIqgY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CrIHbI+2A1Dz2XiHviLEX4FmKapZh7S06NIYUDjUyO3nOQ/3Jpn5XsTSF5mPejqLc aEaDDbJQRmEJswGhSIah7FMoIp7fxI60qp9sR2DlLD7lCEF26Z1/1KCYImLUJcWZbc 4pCTLH6n4l1lVN3TRu+yr7P1wrsL7TmW3sxt3wZJZ3GJj2/RgHEJS9TzlRFJIVEVzP Z23Ru/me3nYwDFcoaN/ezsnkVU5DjEwy8xMqv8FNwG3F8tnTvQnm2eFDLxf1A0+vbg pLySXVw/Wfy0NKZQBavgfiuoR7bKq8uXtiZ1dATygL56BmNSelm5+zcekl5cDEuuXr Oo+wqne9iY2iA== From: Zack Rusin To: dri-devel@lists.freedesktop.org Subject: [PATCH v5 9/9] drm: Introduce documentation for hotspot properties Date: Tue, 18 Jul 2023 21:42:18 -0400 Message-Id: <20230719014218.1700057-10-zack@kde.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230719014218.1700057-1-zack@kde.org> References: <20230719014218.1700057-1-zack@kde.org> MIME-Version: 1.0 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: , Reply-To: Zack Rusin Cc: javierm@redhat.com, banackm@vmware.com, krastevm@vmware.com, ppaalanen@gmail.com, iforbes@vmware.com, mombasawalam@vmware.com 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 Reviewed-by: Javier Martinez Canillas Acked-by: Pekka Paalanen Reviewed-by: Simon Ser --- 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 c92d425cb2dd..7159b3e90a8a 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 1dc00ad4c33c..f3f2eae83cca 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