Re: platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe

["Daniel Walker (danielwa)" <danielwa@cisco.com>]

On Wed, Nov 13, 2024 at 06:04:44PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 13-Nov-24 5:33 PM, Hans de Goede wrote:
> > Hi,
> > 
> > On 13-Nov-24 5:24 PM, Hans de Goede wrote:
> >> Hi,
> >>
> >> On 13-Nov-24 4:42 PM, Daniel Walker (danielwa) wrote:
> >>>
> >>> Hi,
> >>>
> >>> I bisected an issue of a missing pci device to commit 2841631 the commit title
> >>> in the subject line which was included in v6.1 stable branch.
> >>>
> >>> There was a later fix for a similar missing pci device commit 36c676e2 which
> >>> appears to be for Goldmont/Apollo Lake. The hardware I'm using is
> >>> Goldmont/Denverton. This fix did not appear to change the behavior I'm seeing.
> >>>
> >>> The pci device which is disappearing is a custom gpio device.
> >>>
> >>> I tested v6.12-rc5-next to see if any other changes had fixed the issue, but there was
> >>> no change in behavior since commit 2841631 .
> >>>
> >>> When booting up the device is shown in the pci boot messages but the device
> >>> doesn't end up making it to lspci once you get to a prompt.
> >>
> >> Please give the attached patch a try, this will hopefully fix things.
> >>
> >> Once I have confirmation that this fixes things I'll post it to the list.
> >>
> >> Note this will not backport to the 6.1 stable branch cleanly due to
> >> changes in the x86_cpu_id macros in mainline. Backporting it should
> >> be trivial. Please send a backport to stable@vger.kernel.org yourself
> >> once this has been merged upstream.
> >>
> >> If you backport this, please also backport 36c676e2 first.
> > 
> > Never mind, self nack. This is correct for Gemini Lake which
> > has its SPI at device.function 13.2 like Apollo Lake.
> > 
> > But looking at the dmesg Denverton actually has it at 1f.1
> > aka 31.1 like most other Intel SoCs.
> > 
> > Which make me wonder why this does not work on Denverton.
> > 
> > It probably has something to do with these 2 messages:
> > 
> > pci 0000:00:1f.1: BAR 0 [mem 0xfd000000-0xfdffffff 64bit]: can't claim; no compatible bridge window
> > pci 0000:00:1f.1: BAR 0 [mem 0x280000000-0x280ffffff 64bit]: assigned
> > 
> > I'm guessing that this re-assignment is messing up
> > the p2sb BAR caching, after which things go wrong.
> 
> Hmm, but that should be fixed by 2c6370e66076 ("platform/x86: p2sb: Don't init until unassigned resources have been assigned")
> 
> and you are seeing this with 6.12, which has that.
> 
> Can you try adding a pr_info() to the top of p2sb_cache_resources()
> with 6.12 and then collec a new dmesg ?
> 
> If that pr_info() is done after the:
> 
> pci 0000:00:1f.1: BAR 0 [mem 0x280000000-0x280ffffff 64bit]: assigned
> 
> message then that does not explain things.
> 

I haven't testing adding a pr_info() but the messages seem to happen in the same
order in both working and non-working cases.

Does that matter?

Daniel