[Mesa-dev] [PATCH 2/8] panfrost: Detect GPU version at runtime

[Alyssa Rosenzweig]

>  /* If set, we'll require the use of single render-target framebuffer
>   * descriptors (SFBD), for older hardware -- specifically, <T760 hardware, If

This require_sfbd field should also be set at the same time. In
particular, we'll want a (kernel-agnostic) routine to determine whether
a given chip version supports MFBD, so we know to use it or not.

In kernel-space, this corresponds to the "FEATURE_MRT" flag. We'll want
to import this to userspace, but tl;dr "T760+ is MFBD, T6XX/T720 is
SFBD".

> +        ctx->is_t6xx = pscreen->driver->query_gpu_version(pscreen) == 0x0750;

Where did this magic number come from? Is that for T760 or actually T600
or something else or...? For Midgard only, I suppose <= 0x0750 is
probably what you want but we'll see.

> +	unsigned (*query_gpu_version) (struct panfrost_screen *screen);

I'll implement this in the non-DRM module as well (tonight, if I get
time for it), but that's needed for merging to avoid regressing. Just
making a mental note to self -- nothing for you to worry about here :)
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