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drm: Clarify semantics of struct drm_mode_config.{min, max}_{width, height}

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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 <tzimmermann@suse.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211110103702.374-10-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2021-11-10 11:37:02 +01:00
parent 9239f3e180
commit 84e9dfd518
2 changed files with 28 additions and 0 deletions
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15
Documentation/gpu/todo.rst
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@ -452,6 +452,21 @@ Contact: Thomas Zimmermann <tzimmermann@suse.de>, 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 <tzimmermann@suse.de>
Level: Intermediate
Core refactorings
=================

13
include/drm/drm_mode_config.h
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@ -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 {
/**