Hi Christian Am 12.11.20 um 18:16 schrieb Christian König: > Am 12.11.20 um 14:21 schrieb Thomas Zimmermann: >> In order to avoid eviction of vmap'ed buffers, pin them in their GEM >> object's vmap implementation. Unpin them in the vunmap implementation. >> This is needed to make generic fbdev support work reliably. Without, >> the buffer object could be evicted while fbdev flushed its shadow buffer. >> >> In difference to the PRIME pin/unpin functions, the vmap code does not >> modify the BOs prime_shared_count, so a vmap-pinned BO does not count as >> shared. >> >> The actual pin location is not important as the vmap call returns >> information on how to access the buffer. Callers that require a >> specific location should explicitly pin the BO before vmapping it. > > Well is the buffer supposed to be scanned out? No, not by the fbdev helper. > > If yes then the pin location is actually rather important since the > hardware can only scan out from VRAM. For relocatable BOs, fbdev uses a shadow buffer that makes all any relocation transparent to userspace. It flushes the shadow fb into the BO's memory if there are updates. The code is in drm_fb_helper_dirty_work(). [1] During the flush operation, the vmap call now pins the BO to wherever it is. The actual location does not matter. It's vunmap'ed immediately afterwards. For dma-buf sharing, the regular procedure of pin + vmap still apply. This should always move the BO into GTT-managed memory. Best regards Thomas [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/drm_fb_helper.c#n432 > > Regards, > Christian. > >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> >> --- >> drivers/gpu/drm/radeon/radeon_gem.c | 51 +++++++++++++++++++++++++++-- >> 1 file changed, 49 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c >> b/drivers/gpu/drm/radeon/radeon_gem.c >> index d2876ce3bc9e..eaf7fc9a7b07 100644 >> --- a/drivers/gpu/drm/radeon/radeon_gem.c >> +++ b/drivers/gpu/drm/radeon/radeon_gem.c >> @@ -226,6 +226,53 @@ static int radeon_gem_handle_lockup(struct >> radeon_device *rdev, int r) >> return r; >> } >> +static int radeon_gem_object_vmap(struct drm_gem_object *obj, >> struct dma_buf_map *map) >> +{ >> + static const uint32_t any_domain = RADEON_GEM_DOMAIN_VRAM | >> + RADEON_GEM_DOMAIN_GTT | >> + RADEON_GEM_DOMAIN_CPU; >> + >> + struct radeon_bo *bo = gem_to_radeon_bo(obj); >> + int ret; >> + >> + ret = radeon_bo_reserve(bo, false); >> + if (ret) >> + return ret; >> + >> + /* pin buffer at its current location */ >> + ret = radeon_bo_pin(bo, any_domain, NULL); >> + if (ret) >> + goto err_radeon_bo_unreserve; >> + >> + ret = drm_gem_ttm_vmap(obj, map); >> + if (ret) >> + goto err_radeon_bo_unpin; >> + >> + radeon_bo_unreserve(bo); >> + >> + return 0; >> + >> +err_radeon_bo_unpin: >> + radeon_bo_unpin(bo); >> +err_radeon_bo_unreserve: >> + radeon_bo_unreserve(bo); >> + return ret; >> +} >> + >> +static void radeon_gem_object_vunmap(struct drm_gem_object *obj, >> struct dma_buf_map *map) >> +{ >> + struct radeon_bo *bo = gem_to_radeon_bo(obj); >> + int ret; >> + >> + ret = radeon_bo_reserve(bo, false); >> + if (ret) >> + return; >> + >> + drm_gem_ttm_vunmap(obj, map); >> + radeon_bo_unpin(bo); >> + radeon_bo_unreserve(bo); >> +} >> + >> static const struct drm_gem_object_funcs radeon_gem_object_funcs = { >> .free = radeon_gem_object_free, >> .open = radeon_gem_object_open, >> @@ -234,8 +281,8 @@ static const struct drm_gem_object_funcs >> radeon_gem_object_funcs = { >> .pin = radeon_gem_prime_pin, >> .unpin = radeon_gem_prime_unpin, >> .get_sg_table = radeon_gem_prime_get_sg_table, >> - .vmap = drm_gem_ttm_vmap, >> - .vunmap = drm_gem_ttm_vunmap, >> + .vmap = radeon_gem_object_vmap, >> + .vunmap = radeon_gem_object_vunmap, >> }; >> /* > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
