Messages in this thread | | | Date | Wed, 10 Mar 2021 19:02:22 +0000 | From | Paul Cercueil <> | Subject | Re: [PATCH v2 0/5] Add option to mmap GEM buffers cached |
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Hi Thomas,
Le lun. 8 mars 2021 à 9:41, Thomas Zimmermann <tzimmermann@suse.de> a écrit : > Hi Paul, > > having individual functions for each mode only makes sense if the > decision is at compile time. But in patch 5, you're working around > your earlier design by introducing in-driver helpers that select the > correct CMA function. > > In SHMEM helpers we have the flag map_wc in the GEM structure that > selects the pages caching mode (wc vs uncached). I think CMA should > use this design as well. Have a map_noncoherent flag in the CMA GEM > object and set it from the driver's implementation of > gem_create_object.
Is that a new addition? That severely reduces the patchset size, which is perfect.
I'll send a V3 then.
Cheers, -Paul
> And in the long run, we could try to consolidate all drivers/helpers > mapping flags in struct drm_gem_object. > > Best regards > Thomas > > Am 07.03.21 um 21:28 schrieb Paul Cercueil: >> Rework of my previous patchset which added support for GEM buffers >> backed by non-coherent memory to the ingenic-drm driver. >> >> Having GEM buffers backed by non-coherent memory is interesting in >> the particular case where it is faster to render to a non-coherent >> buffer then sync the data cache, than to render to a write-combine >> buffer, and (by extension) much faster than using a shadow buffer. >> This is true for instance on some Ingenic SoCs, where even simple >> blits (e.g. memcpy) are about three times faster using this method. >> >> For the record, the previous patchset was accepted for 5.10 then had >> to be reverted, as it conflicted with some changes made to the DMA >> API. >> >> This new patchset is pretty different as it adds the functionality to >> the DRM core. The first three patches add variants to existing >> functions >> but with the "non-coherent memory" twist, exported as GPL symbols. >> The >> fourth patch adds a function to be used with the damage helpers. >> Finally, the last patch adds support for non-coherent GEM buffers to >> the >> ingenic-drm driver. The functionality is enabled through a module >> parameter, and is disabled by default. >> >> Cheers, >> -Paul >> >> Paul Cercueil (5): >> drm: Add and export function drm_gem_cma_create_noncoherent >> drm: Add and export function drm_gem_cma_dumb_create_noncoherent >> drm: Add and export function drm_gem_cma_mmap_noncoherent >> drm: Add and export function drm_gem_cma_sync_data >> drm/ingenic: Add option to alloc cached GEM buffers >> >> drivers/gpu/drm/drm_gem_cma_helper.c | 223 >> +++++++++++++++++++--- >> drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 49 ++++- >> drivers/gpu/drm/ingenic/ingenic-drm.h | 4 + >> drivers/gpu/drm/ingenic/ingenic-ipu.c | 14 +- >> include/drm/drm_gem_cma_helper.h | 13 ++ >> 5 files changed, 273 insertions(+), 30 deletions(-) >> > > -- > 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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