Hi Am 25.10.19 um 15:32 schrieb Gerd Hoffmann: > Hi, > >>> I had a flag to set this in the initial version of the shmem helper >>> modeled after udl, but Thomas Hellstrom brought up a question and it was >>> dropped. The issue was beyond my understanding: >>> >>> [PATCH v3 0/2] drm: Add shmem GEM library >>> https://lists.freedesktop.org/archives/dri-devel/2018-September/190001.html >> >> If I understand that discussion correctly, the concern was that write >> combining and shared memory would not work well together. So you went >> with always-cached? >> >> Just recently, Gerd added unconditional write combining in rev 0be8958936. > > Well, it's not really added. It's the same thing drm_gem_mmap_obj() > does for you when you don't have a drm_gem_object_funcs.mmap callback. > > But, yes, the reason this is done in the driver's mmap() callback with > the new mmap code path is to give drivers the option to override this > by supplying their own mmap() handler. So going with shmem helpers + > custom mmap callback is a reasonable approach. > > HTH, Absolutely. Thanks everyone for the feedback. Best regards Thomas > Gerd > > _______________________________________________ > 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
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