On Wed, May 26, 2021 at 09:58:36PM +0100, Will Deacon wrote:
> On Tue, May 11, 2021 at 01:40:20AM +0200, Maximilian Luz wrote:
> > The Microsoft Surface Pro X has host bridges defined as
> >
> > Name (_HID, EisaId ("PNP0A08") /* PCI Express Bus */) // _HID: Hardware ID
> > Name (_CID, EisaId ("PNP0A03") /* PCI Bus */) // _CID: Compatible ID
> >
> > Method (_CRS, 0, NotSerialized) // _CRS: Current Resource Settings
> > {
> > Name (RBUF, ResourceTemplate ()
> > {
> > Memory32Fixed (ReadWrite,
> > 0x60200000, // Address Base
> > 0x01DF0000, // Address Length
> > )
> > WordBusNumber (ResourceProducer, MinFixed, MaxFixed, PosDecode,
> > 0x0000, // Granularity
> > 0x0000, // Range Minimum
> > 0x0001, // Range Maximum
> > 0x0000, // Translation Offset
> > 0x0002, // Length
> > ,, )
> > })
> > Return (RBUF) /* \_SB_.PCI0._CRS.RBUF */
> > }
> >
> > meaning that the memory resources aren't (explicitly) defined as
> > "producers", i.e. host bridge windows.
> >
> > Commit 8fd4391ee717 ("arm64: PCI: Exclude ACPI "consumer" resources from
> > host bridge windows") introduced a check that removes such resources,
> > causing BAR allocation failures later on:
> >
> > [ 0.150731] pci 0002:00:00.0: BAR 14: no space for [mem size 0x00100000]
> > [ 0.150744] pci 0002:00:00.0: BAR 14: failed to assign [mem size 0x00100000]
> > [ 0.150758] pci 0002:01:00.0: BAR 0: no space for [mem size 0x00004000 64bit]
> > [ 0.150769] pci 0002:01:00.0: BAR 0: failed to assign [mem size 0x00004000 64bit]
> >
> > This eventually prevents the PCIe NVME drive from being accessible.
> >
> > On x86 we already skip the check for producer/window due to some history
> > with negligent firmware. It seems that Microsoft is intent on continuing
> > that history on their ARM devices, so let's drop that check here too.
> >
> > Signed-off-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>
> > ---
> >
> > Please note: I am not sure if this is the right way to fix that, e.g. I
> > don't know if any additional checks like on IA64 or x86 might be
> > required instead, or if this might break things on other devices. So
> > please consider this more as a bug report rather than a fix.
> >
> > Apologies for the re-send, I seem to have unintentionally added a blank
> > line before the subject.
> >
> > ---
> > arch/arm64/kernel/pci.c | 14 --------------
> > 1 file changed, 14 deletions(-)
>
> Adding Lorenzo to cc, as he'll have a much better idea about this than me.
>
> This is:
>
> https://lore.kernel.org/r/20210510234020.1330087-1-luzmaximilian@xxxxxxxxx
Sigh. We can't apply this patch since it would trigger regressions on
other platforms (IIUC the root complex registers would end up in the
host bridge memory windows).
I am not keen on reverting commit 8fd4391ee717 because it does the
right thing.
I think this requires a quirk and immediate reporting to Microsoft.
Bjorn, what are your thoughts on this ?
Thanks,
Lorenzo
