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TAGGED_RCPT(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:dkim,suse.de:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.com:url,bootlin.com:url] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -3.01 X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: A4A2B4D20D Hi Am 11.03.26 um 05:55 schrieb Chen-Yu Tsai: > On Tue, Mar 10, 2026 at 4:21 PM Thomas Zimmermann wrote: >> Hi >> >> Am 10.03.26 um 04:25 schrieb Chen-Yu Tsai: >>> In commit 9b54a32c7c6a ("drm/mediatek: mtk_gem: Partial refactor and >>> use drm_gem_dma_object") the MediaTek DRM driver was refactored to use >>> drm_gem_dma_object, but custom callbacks were still needed to deal with >>> using the first device of the pipeline as the DMA device, instead of >>> the MMSYS device that the DRM driver binds to. >>> >>> Turns out there is already partial support for dedicated DMA devices in >>> the DRM subsystem for PRIME imports. The preceding patches add support >>> for dedicated DMA devices to the GEM DMA helpers. >>> >>> This allows us to just set the dedicated DMA device for the DRM device, >>> and drop all the custom GEM callbacks. Also drop the .dma_dev field >>> from the driver private data as it is no longer needed. >> My impression is that this patch should be split up: first replace >> dma_dev with the dma device; then replace the now-duplicate code with >> shared helpers. > I'm not sure which of the following you are thinking about: > > a) one patch with just the drm_dev_set_dma_dev() call, > one patch dropping the custom GEM callbacks > > In this case the first patch has no actual effect, since nothing is using > drm_dev->dma_dev. I think this is not a good split. > > b) one patch adding drm_dev_set_dma_dev() and replacing priv->dma_dev > with drm_dev_dma_dev(), > one patch dropping the custom GEM callbacks > > In this case the first patch would modify a bunch of places that then > get dropped in the second. The churn maybe isn't worth it. > > c) one patch adding drm_dev_set_dma_dev() and replacing > drm_gem_prime_import_dev() with drm_gem_prime_import(), > one patch dropping the custom GEM callbacks > > Functionally the second patch would depend on the first. Not my call to make, but the driver maintainers. What I meant was option b). Switching dma_dev for drm_dev_dma_dev() and replacing the mediatek code with common helpers can both introduce regressions.  Having two patches might make later bisecting easier. > > > I still think having one single patch is better. > >>> There are slight differences in the mmap helper: the VM_DONTDUMP and >>> VM_IO flags are no longer set. Both were lifted from drm_gem_mmap_obj(). >>> VM_IO probably doesn't make sense since the buffer is allocated using >>> dma_alloc_attrs(). >> We can add VM_DONTDUMP to gem-dma's mmap helper. [1] It's most likely >> the right thing to not dump graphics buffers and standard practice in >> most other GEM memory managers. > Makes sense. I can add a patch to the series to do this. Rather send it out separately. This affects many drivers and we shouldn't hide such a change somewhere in an unrelated series. Best regards Thomas > >> [1] >> https://elixir.bootlin.com/linux/v6.19.6/source/drivers/gpu/drm/drm_gem_dma_helper.c#L537 >> >>> Signed-off-by: Chen-Yu Tsai >> The changes look correct, so I'm here's the >> >> Reviewed-by: Thomas Zimmermann >> >> But this patch requires a review from the driver maintainer as well. > Sure, and I need to respin the series because I forgot to remove the > deleted file from the Makefile. > > > Thanks > ChenYu -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)