On Sat, 18 Feb 2023 11:49:52 +0100 Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > 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. I'll check that GMUX_MMIO_COMMAND_SEND (16th byte) is not 0xff, as if the gmux is present it will reset that to 0x00, unless a command isn't finished yet, in which case it will be one of 0x1, 0x4, 0x41, or 0x44. > > 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 > >>> > >>> > >> > > >
