On Wed, 10 Apr 2019 at 22:45, Ilia Mirkin <imir...@alum.mit.edu> wrote: > > All docs are in the proper method address, i.e. "in bytes" -- in the > future, please refer to them that way since all the code and > documentation do. > > There is no reference to method 2c8 in the mesa driver (except the > GLOBAL_BASE thing that's only on fermi, I won't get into the details > of what that does, but it's completely irrelevant to what you're > looking at, and gone on Kepler). > > There's also no reference to method 2c8 in libdrm_nouveau nor in the > nouveau kernel driver (that I can see). > > Some notes I have do indicate that method 2c8 does in fact exist > starting with the KeplerC 3d class (GK208 iirc), and has something to > do with "sync points" whatever those are. However we've never used it, > and I don't have any details on how it operates. Syncpoints are only available on Tegra HW as far as I know, and are used to implement some android synchronization method. We don't use them, nor do I know any of their details off the top of my head.
The NVGPU driver source appears to indicate it makes use of them, and would probably be a reasonable reference for you. Ben. > > All the waiting is done using the SEMAPHORE_* methods I pointed at in > my earlier email. If the CPU has to wait for the GPU to finish > something, we can use a kernel-based wait, which basically waits for > an interrupt to occur, or we can use a CPU-based wait which spins and > waits for some value in memory to get to a particular number. If the > CPU does not have to wait, you just want the command stream processing > to wait inside the GPU, then you can also use those SEMAPHORE_* > methods, e.g. nvc0_hw_query_fifo_wait in nvc0_query_hw.c. > > Hope this helps, > > -ilia > > On Wed, Apr 10, 2019 at 6:59 AM Fernando Sahmkow <fsahmko...@gmail.com> wrote: > > > > yeah 0xB2 in words not bytes (*4). Nouveau does write this method in > > Maxwell GPUs (we have compiled test apps with nouveau and asserted it was > > written). Here's what my colleague fincs REed: > > https://github.com/devkitPro/libdrm_nouveau/blob/master/source/pushbuf.c#L399-L407 > > methods are word aligned (so multiplied by 4 for bytes). As far as I know > > the driver side writes some syncpoints to set fences, this method seems to > > tamper with those syncpoints, the thing is that I don't know why or how. > > > > I think this is related to glFencSync and glWaitClientSync. How are this > > methods implemented from both sides (within the gpu and within the > > driver/host communication) ? > > > > El mié., 10 abr. 2019 a las 0:56, Ilia Mirkin (<imir...@alum.mit.edu>) > > escribió: > >> > >> Hi Fernando, > >> > >> Perhaps you can elaborate? The question doesn't really make sense to me. > >> > >> What register are you talking about? Do you perhaps mean a method call > >> in the b197 class? (And what's 0xB2? Methods are always at multiples > >> of 4... do you mean 0x2c8 perhaps? If so, that's not documented post > >> Fermi in the 3d class.) And lastly, what do you mean by syncpoints > >> exactly? There are various class methods that will allow you to wait > >> for a value in memory to be equal (or greater) than a value in the > >> command stream, for example (e.g. QUERY_GET -- method 0x1b0c, or the > >> fifo-level 0x10..0x1c SEMAPHORE_* methods) -- is that what you're > >> talking about? > >> > >> -ilia > >> > >> On Tue, Apr 9, 2019 at 9:46 PM Fernando Sahmkow <fsahmko...@gmail.com> > >> wrote: > >> > > >> > bump > >> > > >> > El mar., 2 abr. 2019 a las 11:11, Fernando Sahmkow > >> > (<fsahmko...@gmail.com>) escribió: > >> >> > >> >> Hi guys how are you doing? I have some questions on how the GPU handles > >> >> syncpoints from the commandlist. > >> >> > >> >> I do know the register 0xB2 is the one written in the Maxwell3D Engine. > >> >> As far as I know bits 0:15 are the syncpoint id, bit 16 is unknown for > >> >> me, bit 20 is increment? What other bits are set and what should be > >> >> done on increment? > >> >> > >> >> Thanks in advance. > >> > > >> > > >> > > >> > -- > >> > Atentamente, > >> > Fernando A. Sahmkow > >> > Móvil: +584242280286 > >> > Correo: fsahmko...@gmail.com > >> > _______________________________________________ > >> > Nouveau mailing list > >> > nouv...@lists.freedesktop.org > >> > https://lists.freedesktop.org/mailman/listinfo/nouveau > > > > > > > > -- > > Atentamente, > > Fernando A. Sahmkow > > Móvil: +584242280286 > > Correo: fsahmko...@gmail.com > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
