[SRU][Focal][PATCH 0/4] Enable sysfs reporting for 32 GT/s PCI link speed

[Thadeu Lima de Souza Cascardo]

On Tue, May 03, 2022 at 09:42:15AM -0500, Ian May wrote:
> BugLink: https://bugs.launchpad.net/bugs/1970798
> 
> SRU Justification
> 
> [Impact]
> 
> NVIDIA Collective Communication Library software uses sysfs to report performance statistics. Users have reported entries showing "Unknown speed" when they should be reporting "32 GT/s".
> 
> Example:
> "<pci busid="0000:0c:00.0" class="0x020700" vendor="0x15b3" device="0x1021" subsystem_vendor="0x15b3" subsystem_device="0x0082" link_speed="Unknown speed" link_width="16">"
> 
> PCIe 5.0 supports 32 GT/s and is available in the 5.4 kernel, but the patches for properly reporting speeds in sysfs are missing. The following upstream v5.7 patches add the reporting capability.
> 
> PCI ML submission
> https://lore.kernel.org/linux-pci/20200229030706.17835-1-helgaas@kernel.org/
> 
> Upstream Patches
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9cb3985af63555810bb07de50acdf4170771451d
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e56faff57f0b39661093c00e0262d4ab9088830e
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6348a34dcb98d8e285685a205f2a601817fa2d38
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=757bfaa2c3515803dde9a6728bbf8c8a3c5f098a
> 

If these commits are upstream, why are they submitted as SAUCE?

Aside from that, this looks good to me.

Cascardo.

> [Test Plan]
> 
> Testing these speeds requires special hardware. A Test kernel with these patches applied was provided to the customer and they confirmed the proper numbers are reported.
> 
> [Where problems could occur]
> 
> Changes are for reporting info so chance of problems should be low. If a problem did occur it would be with sysfs or pcie driver misreporting speeds.
> 
> [ Other ]
> 
> SF-00333784
> 
> Bjorn Helgaas (2):
>   UBUNTU: SAUCE: PCI: Add pci_speed_string()
>   UBUNTU: SAUCE: PCI: Use pci_speed_string() for all PCI/PCI-X/PCIe
>     strings
> 
> Yicong Yang (2):
>   UBUNTU: SAUCE: PCI: Add 32 GT/s decoding in some macros
>   UBUNTU: SAUCE: PCI: Add PCIE_LNKCAP2_SLS2SPEED() macro
> 
>  drivers/pci/pci-sysfs.c | 27 +++++----------------------
>  drivers/pci/pci.c       | 23 +++++++----------------
>  drivers/pci/pci.h       | 19 +++++++++++--------
>  drivers/pci/probe.c     | 40 ++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/slot.c      | 38 +-------------------------------------
>  include/linux/pci.h     |  2 +-
>  6 files changed, 65 insertions(+), 84 deletions(-)
> 
> -- 
> 2.25.1
> 
> 
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