Re: [PATCH v3 0/2] PCI: Distribute resources for root buses

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Wed, 30 Nov 2022 13:22:19 +0200
Mika Westerberg <mika.westerberg@linux.intel.com> wrote:

> Hi all,
> 
> This is third iteration of the patch series trying to solve the problem
> reported by Chris Chiu [1]. In summary the current resource
> distribution code does not cover the initial device enumeration so if we
> find unconfigured bridges they get the bare minimum.
> 
> This one tries to be slightly more generic and deal with PCI devices in
> addition to PCIe. I've tried this on a system with Maple Ridge
> Thunderbolt controller (the same as in the orignal bug report), on QEMU
> with similar PCI topology using following parameters:
> 
> 	-device pcie-pci-bridge,id=br1					\
> 	-device e1000,bus=br1,addr=2					\
> 	-device pci-bridge,chassis_nr=1,bus=br1,shpc=off,id=br2,addr=3	\
> 	-device e1000,bus=br1,addr=4					\
> 	-device e1000,bus=br2
> 
> Then on a QEMU similar to what Jonathan used when he found out the
> regression with multifunction devices:
> 
> 	-device pcie-root-port,port=0,id=root_port13,chassis=0,slot=2	\
> 	-device x3130-upstream,id=sw1,bus=root_port13,multifunction=on	\
> 	-device e1000,bus=root_port13,addr=0.1				\
> 	-device xio3130-downstream,id=fun1,bus=sw1,chassis=0,slot=3	\
> 	-device e1000,bus=fun1
> 
> The previous versions of the series can be found:
> 
> v2: https://lore.kernel.org/linux-pci/20221114115953.40236-1-mika.westerberg@linux.intel.com/
> v1: https://lore.kernel.org/linux-pci/20221103103254.30497-1-mika.westerberg@linux.intel.com/
> 
> Changes from v2:
>   * Make both patches to work with PCI devices too (do not expect that
>     the bridge is always first device on the bus).
>   * Allow distribution with bridges that do not have all resource
>     windows programmed (thereofore the pathch 2/2 is not revert anymore)

patch

>   * I did not add the tags from Rafael and Jonathan because the code is
>     not exactly the same anymore so was not sure if they still apply.

Fair enough - guess it's time for another look.

> 
> Changes from v1:
>   * Re-worded the commit message to hopefully explain the problem better
>   * Added Link: to the bug report
>   * Update the comment according to Bjorn's suggestion
>   * Dropped the ->multifunction check
>   * Use %#llx in log format.
> 
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=216000
> 
> Mika Westerberg (2):
>   PCI: Take other bus devices into account when distributing resources
>   PCI: Distribute available resources for root buses too
> 
>  drivers/pci/setup-bus.c | 122 ++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 117 insertions(+), 5 deletions(-)
>