VK_EXT_image_drm_format_modifier dependency on samplerYcbcrConversion feature

[Icenowy]

The document of VK_EXT_image_drm_format_modifier extension only declares dependency on "VK_KHR_sampler_ycbcr_conversion OR Vulkan version 1.1".

Do an implementation need to implement samplerYcbcrConversion to implement VK_EXT_image_drm_format_modifier?

By the way, this extension seems to be currently the only way to specify the line stride of an imported image -- the allocator (e.g. a display controller driver) may have different stride alignment requirement with the current Vulkan device. This leads to garbage display output when importing DC's buffer, see https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38810#note_3227522 . If samplerYcbcrConversion is required, maybe it will be useful to have a simpler codepath to enforce the line stride of an imported single-plane image.

[Icenowy]

@cubanismo according to spec's Contact information.

[cubanismo]

TSG Discussion: Need more time for spec research. There may be some missing requirements/interactions here, but no clear yet.

[Icenowy]

(My idea is that it's only the definition of EXT_image_drm_format_modifier depends on enums introduced in KHR_sampler_ycbcr_conversion , so the "KHR_sampler_ycbcr_conversion or Vulkan 1.1" is correct and VVL is wrong)