Does gbm_bo_map() implicitly synchronise?

[Michel Dänzer]

On 2024-06-17 12:29, Pierre Ossman wrote:
>
> Just to avoid any uncertainty, are both of these things done implicitly by gbm_bo_map()/gbm_bo_unmap()?
> 
> I did test adding those steps just in case, but unfortunately did not see an improvement. My order was:
> 
> 1. gbm_bo_import(GBM_BO_USE_RENDERING)
> 2. gbm_bo_get_fd()
> 3. Wait for client to request displaying the buffer
> 4. gbm_bo_map(GBM_BO_TRANSFER_READ)
> 5. select(fd+1, &fds, NULL, NULL, NULL)

*If* select() is needed, it needs to be before gbm_bo_map(), because the latter may perform a blit from the real BO to a staging one for CPU access.


> 6. ioctl(DMA_BUF_IOCTL_SYNC, &{ .flags = DMA_BUF_SYNC_START | DMA_BUF_SYNC_READ })

gbm_bo_map() should do this internally if needed.


> 7. pixman_blt()
> 8. gbm_bo_unmap()


-- 
Earthling Michel Dänzer            |                  https://redhat.com
Libre software enthusiast          |         Mesa and Xwayland developer