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| author | Tim Wawrzynczak <twawrzynczak@chromium.org> | 2021-12-08 21:19:50 -0700 |
|---|---|---|
| committer | Tim Wawrzynczak <twawrzynczak@chromium.org> | 2021-12-22 18:41:39 +0000 |
| commit | 3ee9bb012d874295eb7ef00ad6852c3dca92a1ef (patch) | |
| tree | 1e18007a6157df7d79948f01af62a2d8ec6e2992 /src | |
| parent | a62cb5693b93a4bec3d4c0ae072d9622d6a5ea0f (diff) | |
drivers/generic/bayhub_lv2: Work around known errata
The Bayhub LV2 has a known errata wherein PCI config registers at
offsets 0x234, 0x238, and 0x24C will only correctly accept writes
when they are addressed via a DWORD (32-bit) wide write operation
on the PCIe bus. Offset 0x234 is the LTR max snoop and max no-snoop
latency register, therefore add a finalize callback to this driver
which will program the LTR max-snoop/no-snoop register with a 32-bit
write using the values from pciexp_get_ltr_max_latencies().
BUG=b:204343849
TEST=verified the PCI config space writes took effect on google/taeko
Change-Id: I1813f798faa534fb212cb1a074bc7bcadd17a517
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60016
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/drivers/generic/bayhub_lv2/lv2.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/src/drivers/generic/bayhub_lv2/lv2.c b/src/drivers/generic/bayhub_lv2/lv2.c index 90e1e5d105..7cd8a3651f 100644 --- a/src/drivers/generic/bayhub_lv2/lv2.c +++ b/src/drivers/generic/bayhub_lv2/lv2.c @@ -6,11 +6,32 @@ #include <device/device.h> #include <device/path.h> #include <device/pci.h> +#include <device/pciexp.h> #include <device/pci_ops.h> #include <device/pci_ids.h> #include "chip.h" #include "lv2.h" +/* + * This chip has an errata where PCIe config space registers 0x234, 0x248, and + * 0x24C only support DWORD access, therefore reprogram these in the `finalize` + * callback. + */ +static void lv2_enable_ltr(struct device *dev) +{ + u16 max_snoop, max_nosnoop; + if (!pciexp_get_ltr_max_latencies(dev, &max_snoop, &max_nosnoop)) + return; + + const unsigned int ltr_cap = pciexp_find_extended_cap(dev, PCIE_EXT_CAP_LTR_ID); + if (!ltr_cap) + return; + + pci_write_config32(dev, ltr_cap + PCI_LTR_MAX_SNOOP, (max_snoop << 16) | max_nosnoop); + printk(BIOS_INFO, "%s: Re-programmed LTR max latencies using chip-specific quirk\n", + dev_path(dev)); +} + static void lv2_enable(struct device *dev) { struct drivers_generic_bayhub_lv2_config *config = dev->chip_info; @@ -45,6 +66,7 @@ static struct device_operations lv2_ops = { .enable_resources = pci_dev_enable_resources, .ops_pci = &pci_dev_ops_pci, .enable = lv2_enable, + .final = lv2_enable_ltr, }; static const unsigned short pci_device_ids[] = { |