Re: [PATCH v2] platform/x86: p2sb: Defer P2SB device scan when P2SB device has func 0

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, Mar 04, 2024 at 03:24:58PM +0100, Hans de Goede wrote:
> On 3/4/24 3:17 PM, Andy Shevchenko wrote:
> > On Mon, Mar 04, 2024 at 04:09:49PM +0200, Andy Shevchenko wrote:
> >> On Mon, Mar 04, 2024 at 02:59:57PM +0100, Hans de Goede wrote:
> >>> On 3/4/24 1:13 PM, Shinichiro Kawasaki wrote:
> >>>> On Mar 04, 2024 / 12:04, Hans de Goede wrote:

...

> >>>> Thanks for sharing the insights.
> >>>
> >>> Looking closer at the actual unhiding I don't think accessing func 0
> >>> is the problem. The unhiding is always done on function 0 even when
> >>> retreiving the bar for function 2 (the SPI function).
> >>>
> >>> So taking that into account, as mentioned in the bugzilla, I think
> >>> the problem is probing the other functions (1, 3-7) by calling
> >>> pci_scan_single_device() on them.
> >>
> >> So, why we can't simply call pci_dev_present() on the function in a loop?
> > 
> > pci_device_is_present()
> 
> That takes a pci_dev as argument which we only have after calling
> pci_scan_single_device() and the calling of pci_scan_single_device()
> on some of the other functions is what is suspected of maybe causing
> the issue.
> 
> Also it is likely that if pci_scan_single_device() is actually
> a problem that then what is a problem is running it on an actual
> present device.

Which is weird. But okay, let's work around first the real issue, then
if I have time I will look into datasheet to see if there is anything
special about P2SB device(s).

> Devices which are not there also should not get confused
> by trying to probe them ...

-- 
With Best Regards,
Andy Shevchenko