On Wed, Mar 24, 2021 at 11:13 AM Michel Dänzer <michel@xxxxxxxxxxx> wrote:
On 2021-03-23 4:32 p.m., Mark Yacoub wrote:
> On Tue, Mar 23, 2021 at 11:02 AM Alex Deucher <alexdeucher@xxxxxxxxx> wrote:
>>
>> On Wed, Mar 10, 2021 at 11:15 AM Mark Yacoub <markyacoub@xxxxxxxxxxxx> wrote:
>>>
>>> From: Mark Yacoub <markyacoub@xxxxxxxxxx>
>>>
>>> On initializing the framebuffer, call drm_any_plane_has_format to do a
>>> check if the modifier is supported. drm_any_plane_has_format calls
>>> dm_plane_format_mod_supported which is extended to validate that the
>>> modifier is on the list of the plane's supported modifiers.
>>>
>>> The bug was caught using igt-gpu-tools test: kms_addfb_basic.addfb25-bad-modifier
>>>
>>> Tested on ChromeOS Zork by turning on the display, running an overlay
>>> test, and running a YT video.
>>>
>>> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
>>> Cc: Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: default avatarMark Yacoub <markyacoub@xxxxxxxxxxxx>
>>
>> I'm not an expert with modifiers yet. Will this break chips which
>> don't currently support modifiers?
> No it shouldn't. When you don't support modifiers yet, your will
> default to Linear Modifier (DRM_FORMAT_MOD_LINEAR),
> [...]
No modifier support does not imply linear. It's generally signalled via DRM_FORMAT_MOD_INVALID, which roughly means "tiling is determined by driver specific mechanisms".
Doesn't quite work that way in the kernel sadly. If you don't set DRM_MODE_FB_MODIFIERS then the modifier fields have to be 0 (which happens to alias DRM_FORMAT_MOD_LINEAR and then now deprecated DRM_FORMAT_MOD_NONE). This is verified in shared drm code.
(and all userspace code I've seen simply doesn't set DRM_MODE_FB_MODIFIERS if the incoming modifier is DRM_FORMAT_MOD_INVALID)
--
Earthling Michel Dänzer | https://redhat.com
Libre software enthusiast | Mesa and X developer
_______________________________________________
amd-gfx mailing list
amd-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/amd-gfx
_______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
