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Commit 9e506a7b authored by Tal Gilboa's avatar Tal Gilboa Committed by Bjorn Helgaas
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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: default avatarTal Gilboa <talgi@mellanox.com>
[bhelgaas: changelog, reword log messages, print device capabilities when
not limited, print bandwidth in Gb/s]
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 6db79a88

drivers/pci/pci.c

+32 −0
Original line number Diff line number Diff line
@@ -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

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -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);