Re: [PATCH 6/8] drm/amd/display: Set DC options from modifiers.

On 2020-08-10 2:28 p.m., Daniel Vetter wrote:

Ok just learned that amdgpu hat set/get_tiling, so I'm upgrading my idea here to a very strong recommendation, i.e. please do this except if there's and amd ddx which somehow wants to change tiling mode while a fb exists, and expects this to propagate.

In i915 we even disallow the set_tiling ioctl with an error if an fb exists, just to make sure userspace behaves. Even if userspace uses set_tiling, this way we can at least enforce the same semantics of "client can't pull compositor over the table with a set_tiling at the wrong time" of modifiers.

FWIW, xf86-video-amdgpu doesn't have any code to set the tiling metadata, only Mesa and presumably AMD's Vulkan/OpenGL UMDs do.