Hi, On 2/17/23 13:02, Orlando Chamberlain wrote: > 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. Yes checking for a regular ioread32 returning 0xffffffff sounds like it should work. Can you add a check for that in the next version please ? Note this means we still need to do an iomap + unmap as you pointed out in another email, but I see no way around that. Regards, Hans > >> >> 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 >>> >>> >> >
