From 84e9dfd5185285df55ae9068c89cde1a88baa7b7 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Wed, 10 Nov 2021 11:37:02 +0100 Subject: drm: Clarify semantics of struct drm_mode_config.{min, max}_{width, height} MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add additional information on the semantics of the size fields in struct drm_mode_config. Also add a TODO to review all driver for correct usage of these fields. Signed-off-by: Thomas Zimmermann Acked-by: Noralf Trønnes Link: https://patchwork.freedesktop.org/patch/msgid/20211110103702.374-10-tzimmermann@suse.de --- Documentation/gpu/todo.rst | 15 +++++++++++++++ include/drm/drm_mode_config.h | 13 +++++++++++++ 2 files changed, 28 insertions(+) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 6593c4c4006e..f504d363fef5 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -452,6 +452,21 @@ Contact: Thomas Zimmermann , Christian König, Daniel Vette Level: Intermediate +Review all drivers for setting struct drm_mode_config.{max_width,max_height} correctly +-------------------------------------------------------------------------------------- + +The values in struct drm_mode_config.{max_width,max_height} describe the +maximum supported framebuffer size. It's the virtual screen size, but many +drivers treat it like limitations of the physical resolution. + +The maximum width depends on the hardware's maximum scanline pitch. The +maximum height depends on the amount of addressable video memory. Review all +drivers to initialize the fields to the correct values. + +Contact: Thomas Zimmermann + +Level: Intermediate + Core refactorings ================= diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index 48b7de80daf5..91ca575a78de 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -359,6 +359,19 @@ struct drm_mode_config_funcs { * Core mode resource tracking structure. All CRTC, encoders, and connectors * enumerated by the driver are added here, as are global properties. Some * global restrictions are also here, e.g. dimension restrictions. + * + * Framebuffer sizes refer to the virtual screen that can be displayed by + * the CRTC. This can be different from the physical resolution programmed. + * The minimum width and height, stored in @min_width and @min_height, + * describe the smallest size of the framebuffer. It correlates to the + * minimum programmable resolution. + * The maximum width, stored in @max_width, is typically limited by the + * maximum pitch between two adjacent scanlines. The maximum height, stored + * in @max_height, is usually only limited by the amount of addressable video + * memory. For hardware that has no real maximum, drivers should pick a + * reasonable default. + * + * See also @DRM_SHADOW_PLANE_MAX_WIDTH and @DRM_SHADOW_PLANE_MAX_HEIGHT. */ struct drm_mode_config { /** -- cgit v1.2.3