Hi, On Tue, 4 Sep 2018 at 11:05, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > On Tue, Sep 4, 2018 at 3:00 AM, Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx> wrote: > > +/* The chip this is compatible with. > > + * > > + * If compression is disabled, use > > + * - AMDGPU_CHIP_TAHITI for GFX6-GFX8 > > + * - AMDGPU_CHIP_VEGA10 for GFX9+ > > + * > > + * With compression enabled please use the exact chip. > > + * > > + * TODO: Do some generations share DCC format? > > + */ > > +#define AMDGPU_MODIFIER_CHIP_GEN_SHIFT 40 > > +#define AMDGPU_MODIFIER_CHIP_GEN_MASK 0xff > > Do you really need all the combinations here of DCC + gpu gen + tiling > details? When we had the entire discussion with nvidia folks they > eventually agreed that they don't need the massive pile with every > possible combination. Do you really plan to share all these different > things? > > Note that e.g. on i915 we spec some of the tiling depending upon > buffer size and buffer format (because that's how the hw works), not > using explicit modifier flags for everything. Right. The conclusion, after people went through and started sorting out the kinds of formats for which they would _actually_ export real colour buffers for, that most vendors definitely have fewer than 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 possible formats to represent, very likely fewer than 340,282,366,920,938,463,463,374,607,431,768,211,456 formats, probably fewer than 72,057,594,037,927,936 formats, and even still generally fewer than 281,474,976,710,656 if you want to be generous and leave 8 bits of the 56 available. If you do use 256 bits in order to represent 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 modifiers per format, userspace would start hitting OOM pretty quickly as it attempted to enumerate and negotiate acceptable modifiers. Either that or we need to replace the fixed 64-bit modifier tokens with some kind of eBPF script. Cheers, Daniel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
