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PCI: Add pcie_print_link_status() to log link speed and whether it's limited 

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@mellanox.com>
[bhelgaas: changelog, reword log messages, print device capabilities when
not limited, print bandwidth in Gb/s]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Tal Gilboa 2018-03-30 08:56:47 -05:00 committed by Bjorn Helgaas
parent 6db79a88c6
commit 9e506a7b51
2 changed files with 33 additions and 0 deletions
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32
drivers/pci/pci.c
View File

@ -5288,6 +5288,38 @@ 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, "%u.%03u Gb/s available bandwidth (%s x%d link)\n",
bw_cap / 1000, bw_cap % 1000,
PCIE_SPEED2STR(speed_cap), width_cap);
else
pci_info(dev, "%u.%03u Gb/s available bandwidth, limited by %s x%d link at %s (capable of %u.%03u Gb/s with %s x%d link)\n",
bw_avail / 1000, bw_avail % 1000,
PCIE_SPEED2STR(speed), width,
limiting_dev ? pci_name(limiting_dev) : "<unknown>",
bw_cap / 1000, bw_cap % 1000,
PCIE_SPEED2STR(speed_cap), width_cap);
}
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

1
include/linux/pci.h
View File

@ -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);