[Mesa-dev] [PATCH 4/5] r600g, radeonsi: Use write-combined persistent GTT mappings

[Michel Dänzer]

On 17.07.2014 21:00, Marek Olšák wrote:
> On Thu, Jul 17, 2014 at 12:01 PM, Michel Dänzer <michel at daenzer.net> wrote:
>> From: Michel Dänzer <michel.daenzer at amd.com>
>>
>> This is hopefully safe: The kernel makes sure writes to these mappings
>> finish before the GPU might start reading from them, and the GPU caches
>> are invalidated at the start of a command stream.
>>
> The resource flags actually tell you what you can do. If the COHERENT
> flag is set, the mapping must be cached.

Why is that required? As I explain above, we should satisfy the
requirements of the ARB_buffer_storage extension AFAICT.


As pointed out by you and Grigori in other posts, I should probably just
drop the special treatment of persistent mappings though, so the
placement and flags are derived from the buffer usage.


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer