In new revision of LS7A, some PCIe ports support larger value than 256,
but their maximum supported MRRS values are not detectable. Moreover,
the current loongson_mrrs_quirk() cannot avoid devices increasing its
MRRS after pci_enable_device(). So the only possible way is configure
MRRS of all devices in BIOS, and add a PCI device flag (PCI_DEV_FLAGS_
NO_INCREASE_MRRS) to stop the increasing MRRS operations.
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
drivers/pci/pci.c | 5 +++++
drivers/pci/quirks.c | 6 ++++++
include/linux/pci.h | 2 ++
3 files changed, 13 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b717680377a9..6f0d2f5b6f30 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5802,6 +5802,11 @@ int pcie_set_readrq(struct pci_dev *dev, int rq)
v = (ffs(rq) - 8) << 12;
+ if (dev->dev_flags & PCI_DEV_FLAGS_NO_INCREASE_MRRS) {
+ if (rq > pcie_get_readrq(dev))
+ return -EINVAL;
+ }
+
ret = pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
PCI_EXP_DEVCTL_READRQ, v);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 66e4bea69431..10b3b2057940 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -264,6 +264,12 @@ static void loongson_mrrs_quirk(struct pci_dev *dev)
* any devices attached under these ports.
*/
if (pci_match_id(bridge_devids, bridge)) {
+ dev->dev_flags |= PCI_DEV_FLAGS_NO_INCREASE_MRRS;
+
+ if (pcie_bus_config == PCIE_BUS_DEFAULT ||
+ pcie_bus_config == PCIE_BUS_TUNE_OFF)
+ break;
+
if (pcie_get_readrq(dev) > 256) {
pci_info(dev, "limiting MRRS to 256\n");
pcie_set_readrq(dev, 256);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c20211e59a57..7fb2072a83b8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -227,6 +227,8 @@ enum pci_dev_flags {
PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
/* Don't use Relaxed Ordering for TLPs directed at this device */
PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11),
+ /* Don't increase BIOS's MRRS configuration */
+ PCI_DEV_FLAGS_NO_INCREASE_MRRS = (__force pci_dev_flags_t) (1 << 12),
};
enum pci_irq_reroute_variant {
--
2.27.0
