On Tue, Sep 4, 2018 at 4:43 PM Daniel Vetter <daniel at ffwll.ch> wrote: > > On Tue, Sep 4, 2018 at 3:33 PM, Bas Nieuwenhuizen > <bas at basnieuwenhuizen.nl> wrote: > > On Tue, Sep 4, 2018 at 3:04 PM Daniel Vetter <daniel at ffwll.ch> wrote: > >> > >> On Tue, Sep 04, 2018 at 02:33:02PM +0200, Bas Nieuwenhuizen wrote: > >> > On Tue, Sep 4, 2018 at 2:26 PM Daniel Vetter <daniel at ffwll.ch> wrote: > >> > > > >> > > On Tue, Sep 04, 2018 at 12:44:19PM +0200, Christian König wrote: > >> > > > Am 04.09.2018 um 12:15 schrieb Daniel Stone: > >> > > > > Hi, > >> > > > > > >> > > > > On Tue, 4 Sep 2018 at 11:05, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > >> > > > > > On Tue, Sep 4, 2018 at 3:00 AM, Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl> 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. > >> > > > > >> > > > The problem here is that at least for some parameters we actually don't know > >> > > > which formats are actually used. > >> > > > > >> > > > The following are not real world examples, but just to explain the general > >> > > > problem. > >> > > > > >> > > > The memory configuration for example can be not ASIC specific, but rather > >> > > > determined by whoever took the ASIC and glued it together with VRAM on a > >> > > > board. It is not likely that somebody puts all the VRAM chips on one > >> > > > channel, but it is still perfectly possible. > >> > > > > >> > > > Same is true for things like harvesting, e.g. of 16 channels halve of them > >> > > > could be bad and we need to know which to actually use. > >> > > > >> > > For my understanding: This leaks outside the chip when sharing buffers? > >> > > All the information you only need locally to a given amdgpu instance > >> > > don't really need to be encoded in modifiers. > >> > > > >> > > Pointers to code where this is all decided (kernel and radeonsi would be > >> > > good starters I guess) would be really good here. > >> > > >> > I extracted the information on which bits are relevant mostly from the > >> > AddrFromCoord functions in addrlib in mesa: > >> > > >> > for macro-tiles: > >> > https://gitlab.freedesktop.org/mesa/mesa/blob/master/src/amd/addrlib/r800/egbaddrlib.cpp#L1587 > >> > > >> > for micro-tiles (or the micro-tiles in macro-tiles): > >> > > >> > https://gitlab.freedesktop.org/mesa/mesa/blob/master/src/amd/addrlib/core/addrlib1.cpp#L3016 > >> > >> So this is the decoding thing. How many of these actually exist, even when > >> taking all the other information into account? > >> > >> E.g. given a platform + memory config (seems needed) + drm_fourcc + stride > >> + height + width, how much of all these bits do you actually still freely > >> pick? > > > > Basically you pick ARRAY_MODE (linear, micro-tile, macro-tile, sparse, > > thick variants of macro-tile), MICRO_TILE_MODE(display, non-display, > > depth, display-rotated) + whether to use compression, everything else > > is fixed given those option, the properties of the chip and the > > format. > > > > > >> > >> It might be that all the things you need to know from the memory config > >> don't encode smaller than the macro/micro/whatever else stuff. But that's > >> kinda the angle that we looked at this for everyone else. > >> > >> E.g. for multi-plane stuff, if everyone picks the same config for the > >> 2nd/3rd plane, then you don't actually need to encode that. It just > >> becomes part of the implied stuff in the modifier. > > > > The problem is some GPUs are compatible for say 8-bpp images, but not > > for 32-bpp surfaces. e.g. lets look at the following table showing the > > current configuration for all GFX6-GFX8 GPU: > > > > format: (bank width, bank height, macro tile aspect, num banks) for > > 8-bpp, 16-bpp and 32 bpp single-sample followed by the PIPE_CONFIG > > > > verde: (1, 4, 2, 16) (1, 2, 2, 16) (1, 1, 2, 16) ADDR_SURF_P4_8x16 > > oland: (1, 4, 2, 16) (1, 2, 2, 16) (1, 1, 2, 16) ADDR_SURF_P4_8x16 > > hainan: (1, 4, 2, 16) (1, 2, 2, 16) (1, 1, 2, 16) ADDR_SURF_P2 > > tahiti/pitcairn: (1, 4, 1, 16) (1, 2, 1, 16) (1, 1, 1, 16) > > ADDR_SURF_P8_32x32_8x16 > > bonaire: (1,4,4,16) (1, 2, 4, 16) (1, 1, 2, 16) ADDR_SURF_P4_16x16 > > hawaii: (1, 4, 2, 16) (1, 2, 2, 16) (1, 1, 1, 16) ADDR_SURF_P16_32x32_16x16 > > CIK APUs: (1,4,4, 8), (1,2,4,8), (1, 2, 2, 8) ADDR_SURF_P2 > > topaz: (4, 4, 2, 8) (4, 4, 2, 8) (2, 4, 2, 8) ADDR_SURF_P2 > > fiji: (1, 4, 2, 8) (1, 4, 2, 8) (1, 4, 2, 8) ADDR_SURF_P16_32x32_16x16 > > tonga:: (1, 4, 4, 16), (1, 4, 4, 16) (1, 4, 4, 16) ADDR_SURF_P8_32x32_16x16 > > polaris11/12: (1, 4, 4, 16), (1, 4, 4, 16) (1, 4, 4, 16) ADDR_SURF_P4_16x16 > > polaris10: (1, 4, 4, 16), (1, 4, 4, 16) (1, 4, 4, 16) ADDR_SURF_P8_32x32_16x16 > > stoney,carrizo: (1, 4, 4, 8) (1, 2, 4, 8), (1, 1, 2, 8) ADDR_SURF_P2 > > > > We see here that e.g. Stoney and the CIK APUs are compatible for 8-bpp > > and 16-bpp, but not 32-bpp. or bonaire and polaris11/12 are only > > compatible for 8-bpp. > > > > So we can't just assume that if the first plane properties match that > > they do so for the second plane, because we don't know what GPU it is > > coming from. > > > > And we can make a canonical table from this but then if we change the > > above tables in the kernel that runs into compatibility issues. > > > I think that's roughly what nvidia ended up doing (not sure they > published anything, haven't seen any patches on dri-devel). Two parts: > - Bunch of flags/bits for the major mode, like {display, non-display, > DCC} and so on. > - For each of the major modes a list of enumerated modes actually used > in reality. For DCC this would be the generation, for more plain > formats it would be the above table. Table entries would be per-bpp > (in case that matters, or whatever matters for amd gpus). > > Imo would be totally ok to put the relevant lookup tables into > drm_fourcc.h directly. Or any other suitable place. Right, the issue would be that the tables are configured int he kernel https://cgit.freedesktop.org/~agd5f/linux/tree/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c?h=amd-staging-drm-next#n417 and having a shared hardcoded table means that if the kernel tables change we break userspace. That would be a new commitment on the side of the kernel driver. (If I can get an okay for that commitment from Alex/Christian I'd be totally happy to switch it over) > > From a quick look about 16 bits total. Gives you 40bits of second > chances and "oops totally sorry". I purposefully left 8 bits as a version field for those oopses. > -Daniel > > > > >> -Daniel > >> > >> > > >> > > -Daniel > >> > > > >> > > > > >> > > > Regards, > >> > > > Christian. > >> > > > > >> > > > > > >> > > > > 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 at lists.freedesktop.org > >> > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > >> > > > > >> > > > >> > > -- > >> > > Daniel Vetter > >> > > Software Engineer, Intel Corporation > >> > > http://blog.ffwll.ch > >> > > _______________________________________________ > >> > > dri-devel mailing list > >> > > dri-devel at lists.freedesktop.org > >> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > >> > >> -- > >> Daniel Vetter > >> Software Engineer, Intel Corporation > >> http://blog.ffwll.ch > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch
