On Mi, 2025-08-06 at 10:58 +0200, Christian König wrote: > On 31.07.25 07:36, Philipp Zabel wrote: > > This is an attempt at fixing amd#2295 [1]: > > > > On an AMD Rembrandt laptop with 680M iGPU and 6700S dGPU, calling > > vkEnumeratePhysicalDevices() wakes up the sleeping dGPU, even if all > > the application wants is to find and use the iGPU. This causes a delay > > of about 2 seconds on this system, followed by a few seconds of > > increased power draw until runtime PM turns the dGPU back off again. > > > > [1] https://gitlab.freedesktop.org/drm/amd/-/issues/2295 > > > > Patch 1 avoids power up on some ioctls that don't need it. > > Patch 2 avoids power up on open() by postponing fpriv initialization to > > the first ioctl() that wakes up the dGPU. > > Patches 3 and 4 add AMDGPU_INFO to the list of non-waking ioctls, > > returning cached values for some queries. > > Patch 5 works around an explicit register access from libdrm. > > Patch 6 shorts out the syncobj ioctls while fpriv is still > > uninitialized. This avoids waking up the dGPU during Vulkan syncobj > > feature detection. > > This idea came up multiple times now but was never completed. > > IIRC Pierre-Eric last worked on it, it would probably be a good idea to dig > up his patches from the mailing list.
Thank you, I wasn't aware of those patches [1]. Pierre-Eric did mention them in https://gitlab.freedesktop.org/mesa/mesa/-/issues/13001, but I didn't pick up on that back then. [1] https://lore.kernel.org/all/20240618153003.146168-1-pierre-eric.pelloux-pra...@amd.com/ Is that the latest version? It looks to me like the review stalled out on a disagreement whether the GB_ADDR_CONFIG query should be a separate ioctl or whether it should be added to drm_amdgpu_info_device. The discussion was later continued at https://gitlab.freedesktop.org/mesa/libdrm/-/merge_requests/368, seemingly coming to the conclusion that keeping the register read (but cached) is the way to go? I didn't find a newer series with that implemented. > > > > regards > > Philipp > > > > Signed-off-by: Philipp Zabel <p.za...@pengutronix.de> > > --- > > Alex Deucher (1): > > drm/amdgpu: don't wake up the GPU for some IOCTLs > > > > Philipp Zabel (5): > > drm/amdgpu: don't wake up the GPU when opening the device > > drm/amdgpu: don't query xclk in AMDGPU_INFO_DEV_INFO > > drm/amdgpu: don't wake up the GPU for some AMDGPU_INFO queries > > drm/amdgpu: don't wake up the GPU for mmGB_ADDR_CONFIG register read > > That is both unnecessary an insufficient. Unnecessary because we already have > a mechanism to cache register values and insufficient because IIRC you need > to add a bunch of more registers to the cached list. This series was (just barely) sufficient for my purpose, which was only to make vkEnumeratePhysicalDevices() not wake the dGPU on my Laptop. I didn't realize there already was a caching mechanism in the lower layers. > See Pierre-Erics latest patch set, I think we already solved that but I'm not > 100% sure. If I found the correct version, it seems Sima's suggestion of pushing runtime pm handling down from amdgpu_drm_ioctl into the amdgpu ioctl callbacks [2] would be the best first next step? [2] https://lore.kernel.org/amd-gfx/ZnvJHwnNAvDrRMVG@phenom.ffwll.local/ regards Philipp
