在 2025-09-04星期四的 00:29 +0100，Andre Przywara写道： > Hi, > > the Allwinner A523/A527/T527 family of SoCs feature a Vivante > "VIP9000"(?) NPU, though it seems to be disabled on many SKUs. > See https://linux-sunxi.org/A523#Family_of_sun55iw3 for a table, the > row labelled "NPU" indicates which model has the IP. We suspect it's > all the same die, with the NPU selectively fused off on some > packages. > > Board vendors seem to use multiple SKUs of the SoC on the same board,
In the case of Amlogic things, they seem to provide different DT's, see arch/arm64/boot/dts/amlogic/meson-g12b-a311d-bananapi-m2s.dts and arch/arm64/boot/dts/amlogic/meson-g12b-s922x-bananapi-m2s.dts ; the A311D is NPU-equipped SKU. (Although I don't know why they included different DTSI's and then still enable &npu node in a311d variant of board DT) > so it's hard to say which particular board has the NPU or not. We > figured that on unsupported SoCs all the NPU registers read as 0, > though, so were wondering if that could be considered as a bail-out > check for the driver? > At the moment I get this, on a SoC with a disabled NPU: > [ 1.677612] etnaviv etnaviv: bound 7122000.npu (ops gpu_ops) > [ 1.683849] etnaviv-gpu 7122000.npu: model: GC0, revision: 0 > [ 1.690020] etnaviv-gpu 7122000.npu: Unknown GPU model > [ 1.696145] [drm] Initialized etnaviv 1.4.0 for etnaviv on minor 0 > [ 1.953053] etnaviv-gpu 7122000.npu: GPU not yet idle, mask: > 0x00000000 > > Chen-Yu got this on his board featuring the NPU: > etnaviv-gpu 7122000.npu: model: GC9000, revision: 9003 > > If I get the code correctly, then etnaviv_gpu_init() correctly > detects > the "unsupported" GPU model, and returns -ENXIO, but load_gpu() in > etnaviv_drv.c then somewhat ignores this, since it keeps looking for > more > GPUs, and fails to notice that *none* showed up: > /sys/kernel/debug/dri/etnaviv/gpu is empty in my case. > > Quick questions: > - Is reading 0 from VIVS_HI_CHIP_IDENTITY (or any other of the ID > registers) an invalid ID, so we can use that to detect those > disabled > NPUs? If not, can any other register used to check this? The whole > block seems to be RAZ/WI when the NPU is disabled. > > - Would it be acceptable to change the logic to error out of the > driver's init or probe routine when no GPU/NPU has been found, at > best with a proper error message? As it stands at the moment, the > driver is loaded, but of course nothing is usable, so it keeps > confusing users. > > Happy to provide a patch, but just wanted to test the waters. > > Cheers, > Andre
