[Mesa-dev] [android-x86-devel] Re: gralloc_drm_pipe

[Daniel Stone]

Hey,

On 29 March 2016 at 19:06, Rob Clark <robdclark at gmail.com> wrote:
> On Tue, Mar 29, 2016 at 1:51 PM, Daniel Stone <daniel at fooishbar.org> wrote:
>> Yep, you got it right: in the original intention, the only mappable
>> GBM BOs were cursor BOs. This is mostly because we lacked modifiers,
>> so it was assumed that they would be in a magic undiscoverable tiling
>> format.
>>
>> Now we have modifiers, whilst adding those to the API (both allocation
>> and gbm_bo_get_*() for legacy allocations), you could then do a
>> gbm_bo_{,un}map_range(). I'm assuming these mostly wouldn't actually
>> map and unmap in a VMA sense, but rather primarily perform cache
>> maintenance.
>
> right, or let's say whether the entire vma is mapped or not should be
> implementation specific.
>
> It would probably be useful if the ptr returned had the offset already
> added, since this is how transfer_map works.. and (hopefully?) the
> gralloc API lets us return a separate pitch for the mapped ptr (which
> might be different from the src buffer)?  That would accommodate
> upload/download sanely.  (Fwiw, even some UMA drivers need to do
> staging copies for some formats..  although I guess gralloc probably
> doesn't care about z32_float_s8x24_uint and that sort of thing ;-))

Yep, absolutely agreed. Who volunteers? :)

Cheers,
Daniel