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Subject[PATCH v5 12/14] fm10k: Report PCIe link properties with pcie_print_link_status()
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Date
From: Bjorn Helgaas <bhelgaas@google.com>

Use pcie_print_link_status() to report PCIe link speed and possible
limitations instead of implementing this in the driver itself.

Note that pcie_get_minimum_link() can return misleading information because
it finds the slowest link and the narrowest link without considering the
total bandwidth of the link. If the path contains a 16 GT/s x1 link and a
2.5 GT/s x16 link, pcie_get_minimum_link() returns 2.5 GT/s x1, which
corresponds to 250 MB/s of bandwidth, not the actual available bandwidth of
about 2000 MB/s for a 16 GT/s x1 link.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/net/ethernet/intel/fm10k/fm10k_pci.c | 87 --------------------------
1 file changed, 1 insertion(+), 86 deletions(-)

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
index a434fecfdfeb..aa05fb534942 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
@@ -2120,91 +2120,6 @@ static int fm10k_sw_init(struct fm10k_intfc *interface,
return 0;
}

-static void fm10k_slot_warn(struct fm10k_intfc *interface)
-{
- enum pcie_link_width width = PCIE_LNK_WIDTH_UNKNOWN;
- enum pci_bus_speed speed = PCI_SPEED_UNKNOWN;
- struct fm10k_hw *hw = &interface->hw;
- int max_gts = 0, expected_gts = 0;
-
- if (pcie_get_minimum_link(interface->pdev, &speed, &width) ||
- speed == PCI_SPEED_UNKNOWN || width == PCIE_LNK_WIDTH_UNKNOWN) {
- dev_warn(&interface->pdev->dev,
- "Unable to determine PCI Express bandwidth.\n");
- return;
- }
-
- switch (speed) {
- case PCIE_SPEED_2_5GT:
- /* 8b/10b encoding reduces max throughput by 20% */
- max_gts = 2 * width;
- break;
- case PCIE_SPEED_5_0GT:
- /* 8b/10b encoding reduces max throughput by 20% */
- max_gts = 4 * width;
- break;
- case PCIE_SPEED_8_0GT:
- /* 128b/130b encoding has less than 2% impact on throughput */
- max_gts = 8 * width;
- break;
- default:
- dev_warn(&interface->pdev->dev,
- "Unable to determine PCI Express bandwidth.\n");
- return;
- }
-
- dev_info(&interface->pdev->dev,
- "PCI Express bandwidth of %dGT/s available\n",
- max_gts);
- dev_info(&interface->pdev->dev,
- "(Speed:%s, Width: x%d, Encoding Loss:%s, Payload:%s)\n",
- (speed == PCIE_SPEED_8_0GT ? "8.0GT/s" :
- speed == PCIE_SPEED_5_0GT ? "5.0GT/s" :
- speed == PCIE_SPEED_2_5GT ? "2.5GT/s" :
- "Unknown"),
- hw->bus.width,
- (speed == PCIE_SPEED_2_5GT ? "20%" :
- speed == PCIE_SPEED_5_0GT ? "20%" :
- speed == PCIE_SPEED_8_0GT ? "<2%" :
- "Unknown"),
- (hw->bus.payload == fm10k_bus_payload_128 ? "128B" :
- hw->bus.payload == fm10k_bus_payload_256 ? "256B" :
- hw->bus.payload == fm10k_bus_payload_512 ? "512B" :
- "Unknown"));
-
- switch (hw->bus_caps.speed) {
- case fm10k_bus_speed_2500:
- /* 8b/10b encoding reduces max throughput by 20% */
- expected_gts = 2 * hw->bus_caps.width;
- break;
- case fm10k_bus_speed_5000:
- /* 8b/10b encoding reduces max throughput by 20% */
- expected_gts = 4 * hw->bus_caps.width;
- break;
- case fm10k_bus_speed_8000:
- /* 128b/130b encoding has less than 2% impact on throughput */
- expected_gts = 8 * hw->bus_caps.width;
- break;
- default:
- dev_warn(&interface->pdev->dev,
- "Unable to determine expected PCI Express bandwidth.\n");
- return;
- }
-
- if (max_gts >= expected_gts)
- return;
-
- dev_warn(&interface->pdev->dev,
- "This device requires %dGT/s of bandwidth for optimal performance.\n",
- expected_gts);
- dev_warn(&interface->pdev->dev,
- "A %sslot with x%d lanes is suggested.\n",
- (hw->bus_caps.speed == fm10k_bus_speed_2500 ? "2.5GT/s " :
- hw->bus_caps.speed == fm10k_bus_speed_5000 ? "5.0GT/s " :
- hw->bus_caps.speed == fm10k_bus_speed_8000 ? "8.0GT/s " : ""),
- hw->bus_caps.width);
-}
-
/**
* fm10k_probe - Device Initialization Routine
* @pdev: PCI device information struct
@@ -2326,7 +2241,7 @@ static int fm10k_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
mod_timer(&interface->service_timer, (HZ * 2) + jiffies);

/* print warning for non-optimal configurations */
- fm10k_slot_warn(interface);
+ pcie_print_link_status(interface->pdev);

/* report MAC address for logging */
dev_info(&pdev->dev, "%pM\n", netdev->dev_addr);
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