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| author | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2019-12-16 17:21:13 +0200 |
|---|---|---|
| committer | Patrick Georgi <pgeorgi@google.com> | 2019-12-19 17:50:03 +0000 |
| commit | 94ce79d6c8d4ee04f55be0bb95feb62411ec8d88 (patch) | |
| tree | 7045f0138c9e22196e951be636ce9ace22468669 /src/device | |
| parent | d1371508f525542f3b75de553dc338b9100bde20 (diff) | |
device/pciexp: Match Max_Payload_Size between ends of a link
Ends of a PCIe link may advertise different Max_Payload_Size in
their PCIe Express Capabilities, Device Capabilities block.
For correct operation, both ends of the link need to have their
Device Control Max_Payload_Size programmed to match and not
exceed the other end's Device Capabilities.
Fixes: https://ticket.coreboot.org/issues/218
Change-Id: I8b1de13e9c73abb30e5ccc792918bb4f81e5fe84
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37769
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Diffstat (limited to 'src/device')
| -rw-r--r-- | src/device/pciexp_device.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/device/pciexp_device.c b/src/device/pciexp_device.c index c73c548bb4..479891c5d6 100644 --- a/src/device/pciexp_device.c +++ b/src/device/pciexp_device.c @@ -12,6 +12,7 @@ */ #include <console/console.h> +#include <commonlib/helpers.h> #include <delay.h> #include <device/device.h> #include <device/pci.h> @@ -408,6 +409,46 @@ static void pciexp_enable_aspm(struct device *root, unsigned int root_cap, printk(BIOS_INFO, "ASPM: Enabled %s\n", aspm_type_str[apmc]); } +/* + * Set max payload size of endpoint in accordance with max payload size of root port. + */ +static void pciexp_set_max_payload_size(struct device *root, unsigned int root_cap, + struct device *endp, unsigned int endp_cap) +{ + unsigned int endp_max_payload, root_max_payload, max_payload; + u16 endp_devctl, root_devctl; + u32 endp_devcap, root_devcap; + + /* Get max payload size supported by endpoint */ + endp_devcap = pci_read_config32(endp, endp_cap + PCI_EXP_DEVCAP); + endp_max_payload = endp_devcap & PCI_EXP_DEVCAP_PAYLOAD; + + /* Get max payload size supported by root port */ + root_devcap = pci_read_config32(root, root_cap + PCI_EXP_DEVCAP); + root_max_payload = root_devcap & PCI_EXP_DEVCAP_PAYLOAD; + + /* Set max payload to smaller of the reported device capability. */ + max_payload = MIN(endp_max_payload, root_max_payload); + if (max_payload > 5) { + /* Values 6 and 7 are reserved in PCIe 3.0 specs. */ + printk(BIOS_ERR, "PCIe: Max_Payload_Size field restricted from %d to 5\n", + max_payload); + max_payload = 5; + } + + endp_devctl = pci_read_config16(endp, endp_cap + PCI_EXP_DEVCTL); + endp_devctl &= ~PCI_EXP_DEVCTL_PAYLOAD; + endp_devctl |= max_payload << 5; + pci_write_config16(endp, endp_cap + PCI_EXP_DEVCTL, endp_devctl); + + root_devctl = pci_read_config16(root, root_cap + PCI_EXP_DEVCTL); + root_devctl &= ~PCI_EXP_DEVCTL_PAYLOAD; + root_devctl |= max_payload << 5; + pci_write_config16(root, root_cap + PCI_EXP_DEVCTL, root_devctl); + + printk(BIOS_INFO, "PCIe: Max_Payload_Size adjusted to %d\n", (1 << (max_payload + 7))); +} + static void pciexp_tune_dev(struct device *dev) { struct device *root = dev->bus->dev; @@ -436,6 +477,9 @@ static void pciexp_tune_dev(struct device *dev) /* Check for and enable ASPM */ if (CONFIG(PCIEXP_ASPM)) pciexp_enable_aspm(root, root_cap, dev, cap); + + /* Adjust Max_Payload_Size of link ends. */ + pciexp_set_max_payload_size(root, root_cap, dev, cap); } void pciexp_scan_bus(struct bus *bus, unsigned int min_devfn, |