Am Freitag, den 10.01.2014, 10:23 -0500 schrieb Rob Clark:
On Tue, Jan 7, 2014 at 1:37 PM, Thomas Hellstrom thellstrom@vmware.com wrote:
Conclusion: Avoid using dma-buf mmap() outside of drivers that know exactly what they are doing, and avoid it at all cost.
well, to be fair, if you are using a gpu on the client side and pixman backend on the server side, you probably deserve the results.
Not to say that we shouldn't come up with a better way for sw access to dmabuf, but just saying there are folks out there who would find Benjamin's patch useful in it's current state (for example, platforms where you have open src bits for video decoder but not for gpu).
So I wouldn't block this patch strictly because we don't have a better mmap story yet.
Even with pixman on the server side transferring DMA-BUFs can be a big win, if your display subsystem is able to do the heavy-lifting with planes. I've a prototype where we do this exact thing: use pixman for the shell stuff and play video on a drm_plane.
And even mmap doesn't has to be as sucky as it is ATM, when someone gets some traction behind the bracketed stuff.
Regards, Lucas