On Tue, Sep 4, 2018 at 5:52 PM, Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, Sep 4, 2018 at 4:43 PM Daniel Vetter <daniel@xxxxxxxx> wrote: >> >> On Tue, Sep 4, 2018 at 3:33 PM, Bas Nieuwenhuizen >> <bas@xxxxxxxxxxxxxxxxxxx> wrote: >> > On Tue, Sep 4, 2018 at 3:04 PM Daniel Vetter <daniel@xxxxxxxx> 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@xxxxxxxx> 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@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. >> >> > > > >> >> > > > 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) Yeah it'd make that table uapi - well the compressed from with duplicates removed, if you really want to make it tiny. But you can just add new entries if the heuristics for a given platform changes, as long as you keep the old entries working (if you shipped them ever ofc, otherwise totally ok to change as you see fit). -Daniel >> 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@xxxxxxxxxxxxxxxxxxxxx >> >> > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel >> >> > > > >> >> > > >> >> > > -- >> >> > > Daniel Vetter >> >> > > Software Engineer, Intel Corporation >> >> > > http://blog.ffwll.ch >> >> > > _______________________________________________ >> >> > > dri-devel mailing list >> >> > > dri-devel@xxxxxxxxxxxxxxxxxxxxx >> >> > > 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 -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
