> -----Original Message----- > From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx] > Sent: Friday, March 30, 2018 2:05 PM > To: Tal Gilboa <talgi@xxxxxxxxxxxx> > Cc: Tariq Toukan <tariqt@xxxxxxxxxxxx>; Keller, Jacob E > <jacob.e.keller@xxxxxxxxx>; Ariel Elior <ariel.elior@xxxxxxxxxx>; Ganesh > Goudar <ganeshgr@xxxxxxxxxxx>; Kirsher, Jeffrey T > <jeffrey.t.kirsher@xxxxxxxxx>; everest-linux-l2@xxxxxxxxxx; intel-wired- > lan@xxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-pci@xxxxxxxxxxxxxxx > Subject: [PATCH v5 05/14] PCI: Add pcie_print_link_status() to log link speed and > whether it's limited > > From: Tal Gilboa <talgi@xxxxxxxxxxxx> > > Add pcie_print_link_status(). This logs the current settings of the link > (speed, width, and total available bandwidth). > > If the device is capable of more bandwidth but is limited by a slower > upstream link, we include information about the link that limits the > device's performance. > > The user may be able to move the device to a different slot for better > performance. > > This provides a unified method for all PCI devices to report status and > issues, instead of each device reporting in a different way, using > different code. > > Signed-off-by: Tal Gilboa <talgi@xxxxxxxxxxxx> > [bhelgaas: changelog, reword log messages, print device capabilities when > not limited] > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > --- > drivers/pci/pci.c | 29 +++++++++++++++++++++++++++++ > include/linux/pci.h | 1 + > 2 files changed, 30 insertions(+) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index e00d56b12747..cec7aed09f6b 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -5283,6 +5283,35 @@ u32 pcie_bandwidth_capable(struct pci_dev *dev, > enum pci_bus_speed *speed, > return *width * PCIE_SPEED2MBS_ENC(*speed); > } > > +/** > + * pcie_print_link_status - Report the PCI device's link speed and width > + * @dev: PCI device to query > + * > + * Report the available bandwidth at the device. If this is less than the > + * device is capable of, report the device's maximum possible bandwidth and > + * the upstream link that limits its performance to less than that. > + */ > +void pcie_print_link_status(struct pci_dev *dev) > +{ > + enum pcie_link_width width, width_cap; > + enum pci_bus_speed speed, speed_cap; > + struct pci_dev *limiting_dev = NULL; > + u32 bw_avail, bw_cap; > + > + bw_cap = pcie_bandwidth_capable(dev, &speed_cap, &width_cap); > + bw_avail = pcie_bandwidth_available(dev, &limiting_dev, &speed, > &width); > + > + 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); > +} Personally, I would make thic last one a pci_warn() to indicate it at a higher log level, but I'm ok with the wording, and if consensus is that this should be at info, I'm ok with that. Thanks, Jake > +EXPORT_SYMBOL(pcie_print_link_status); > + > /** > * pci_select_bars - Make BAR mask from the type of resource > * @dev: the PCI device for which BAR mask is made > diff --git a/include/linux/pci.h b/include/linux/pci.h > index f2bf2b7a66c7..38f7957121ef 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1086,6 +1086,7 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum > pci_bus_speed *speed, > u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev > **limiting_dev, > enum pci_bus_speed *speed, > enum pcie_link_width *width); > +void pcie_print_link_status(struct pci_dev *dev); > void pcie_flr(struct pci_dev *dev); > int __pci_reset_function_locked(struct pci_dev *dev); > int pci_reset_function(struct pci_dev *dev);
