Hi, On 2/18/23 13:52, Orlando Chamberlain wrote: > 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. Ok, this sounds good to me, thanks. 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 >>>>> >>>>> >>>> >>> >> >
