Re: [PATCH v5 05/14] PCI: Add pcie_print_link_status() to log link speed and whether it's limited

From: Jakub Kicinski
Date: Fri Apr 13 2018 - 00:33:05 EST


On Fri, 30 Mar 2018 16:05:18 -0500, Bjorn Helgaas wrote:
> + if (bw_avail >= bw_cap)
> + pci_info(dev, "%d Mb/s available bandwidth (%s x%d link)\n",
> + bw_cap, PCIE_SPEED2STR(speed_cap), width_cap);
> + else
> + pci_info(dev, "%d Mb/s available bandwidth, limited by %s x%d link at %s (capable of %d Mb/s with %s x%d link)\n",
> + bw_avail, PCIE_SPEED2STR(speed), width,
> + limiting_dev ? pci_name(limiting_dev) : "<unknown>",
> + bw_cap, PCIE_SPEED2STR(speed_cap), width_cap);

I was just looking at using this new function to print PCIe BW for a
NIC, but I'm slightly worried that there is nothing in the message that
says PCIe... For a NIC some people may interpret the bandwidth as NIC
bandwidth:

[ 39.839989] nfp 0000:04:00.0: Netronome Flow Processor NFP4000/NFP6000 PCIe Card Probe
[ 39.848943] nfp 0000:04:00.0: 63.008 Gb/s available bandwidth (8 GT/s x8 link)
[ 39.857146] nfp 0000:04:00.0: RESERVED BARs: 0.0: General/MSI-X SRAM, 0.1: PCIe XPB/MSI-X PBA, 0.4: Explicit0, 0.5: Explicit1, fre4

It's not a 63Gbps NIC... I'm sorry if this was discussed before and I
didn't find it. Would it make sense to add the "PCIe: " prefix to the
message like bnx2x used to do? Like:

nfp 0000:04:00.0: PCIe: 63.008 Gb/s available bandwidth (8 GT/s x8 link)

Sorry for a very late comment.