On Fri, 17 Feb 2023 11:05:31 +1100 Orlando Chamberlain <orlandoch.dev@xxxxxxxxx> wrote: > > > > Question are we not worried about MacBooks with an "APP000B" > > ACPI device (with a value IORSOURCE_MEM entry) but which do not > > actually have a gmux, because they are iGPU only ? > > It looks like iMac20,1, iMac20,2, and iMacPro1,1 have APP000B: > > apple_gmux: Failed to find gmux I/O resource > > iMac20,2: https://linux-hardware.org/?probe=ec2af584b3&log=dmesg > iMac20,1: https://linux-hardware.org/?probe=fee7644b9c&log=dmesg > iMacPro1,1: https://linux-hardware.org/?probe=6c26c9ff8c&log=dmesg > > But I'm not sure if they actually have it or not. I'll see if I can > get people with those models to test if it's a real gmux. There does > seem to be a pattern in that those three all have AMD GPU's. Kerem Karabay managed to find the acpi tables and macOS's ioreg from and iMacPro1,1: https://github.com/khronokernel/DarwinDumped/blob/master/iMacPro/iMacPro1%2C1/Darwin%20Dumper/DarwinDumper_3.0.4_30.12_15.30.40_iMacPro1%2C1_Apple_X64_High%20Sierra_17C2120_apple/ACPI%20Tables/DSL/DSDT.dsl#L10423 https://github.com/khronokernel/DarwinDumped/blob/master/iMacPro/iMacPro1%2C1/Darwin%20Dumper/DarwinDumper_3.0.4_30.12_15.30.40_iMacPro1%2C1_Apple_X64_High%20Sierra_17C2120_apple/IORegistry/IOReg.txt#L5096 The DSDT table has the same APP000B device as MacBooks with actual gmux, while the ioreg has no mention of Apple's driver AppleMuxControl2 being used for that device. I think that confirms Apple has not fixed the issue of putting APP000B's where they don't need to. Solutions to this I can think of are: - Use DMI matching to ignore product_names "iMacPro1,1" "iMac20,1", "iMac20,2" - Maybe check if the MMIO region for gmux is filled with 0xff* *I don't know if this would work or not as I don't have a machine to check with. On my machine everything surrounding the 16 bytes used for gmux is 0xff: # hexdump -n48 -C -s 0xfe0b01f0 /dev/mem fe0b01f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| fe0b0200 00 00 3e 4f 00 00 00 00 00 00 00 00 00 00 14 00 |..>O............| fe0b0210 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| so maybe on the iMacPro and iMac's, this would all be 0xff. > > I've looked at dmesg or at least lsmod on all the models with the T2 > chip and there wasn't evidence of any other models having that error > or having apple-gmux loaded on any models that shouldn't have a gmux, > other than the three mentioned above. Of course I don't know if its > possible for there to be firmware versions where this isn't the case. > > > > > I have learned the hard way (through backlight control regressions > > in 6.1) that at least some older model MacBooks with an IO resource > > have an APP000B ACPI device without them actually having a gmux, > > these get caught by the version check and then do not pass the > > indexed check so that apple_gmux_detect() properly returns false. > > > > Maybe make gmux_mmio_read32() a static inline inside > > include/linux/apple-gmux.h and try to read the version here ? > > For that would we need to ioremap() and iounmap()? > > > > Has this been tested on iGPU only T2 Macs? > > I don't think so. > > > > > Regards, > > > > Hans > > > > >
