Re: Possible PCI Regression Linux 5.3-rc1

[Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>]

On Mon, Aug 05, 2019 at 03:34:50PM +0300, Mika Westerberg wrote:
> Hi,
> 
> On Sun, Aug 04, 2019 at 08:47:43AM +0000, Nicholas Johnson wrote:
> > Reversing the following commit solves the issue:
> > 
> > commit c2bf1fc212f7e6f25ace1af8f0b3ac061ea48ba5
> > Author: Mika Westerberg <mika.westerberg@linux.intel.com>
> > PCI: Add missing link delays required by the PCIe spec
> > 
> > Mika, care to weigh in (assuming you are back from four weeks leave)? 
> 
> I'm back now.
> 
> > Clearly this creates delays in "lspci -vt" in some Thunderbolt systems, 
> > but not all - otherwise you would have caught it. You mentioned Ice Lake 
> > in the commit log so perhaps it works fine on Ice Lake.
> 
> I also tried it on other systems but it may be that something is
> missing. Can you add "pciepordrv.dyndbg" to the kernel command line (or
> change the dev_dbg() in wait_for_downstream_link() to dev_info() instead
> and attach the dmesg along with full 'sudo lspci -vv' output to the
> following bugzilla (as I think they are the same issue in the end):
> 
>   https://bugzilla.kernel.org/show_bug.cgi?id=204413
> 
> Thanks!

Done. Please note the update I sent to my own email with more 
information, elaborating that it is reading the config from under the 
NHI which causes the delay. If bus 05 is under the NHI, then the 
following command has a delay:

$ cat /sys/bus/pci/devices/0000\:05\:00.0/config

Whereas reading config from all the other busses is fine. This is what 
is holding up the lspci command.

If possible, please look over my patches briefly to catch any silly 
mistakes or trivial changes to get stuff out of the way for thorough 
review later. I really want to at least get the alignment patch in which 
will help Linux with native enumeration and solve your bug report.

Thanks!

Regards,
Nicholas.