[PATCH v3] PCI: Disable ASPM L0s for Realtek RTS525A

[Max Lee <max.lee@canonical.com>]

The Realtek RTS525A PCIe card reader reports an AER Correctable Replay
Timer Timeout storm when ASPM L0s is enabled on its link.  On an affected
HP ZBook Power 16 inch G11, the Root Port received tens of millions of
AER interrupts from the RTS525A even when the rtsx_pci driver was
blacklisted and the endpoint was not enabled by a driver.

Testing with OS-native AER control showed that disabling only L0s on the
RTS525A link stops new AER interrupt and counter growth while leaving L1
enabled.  Disabling L1, L1 substates, or Clock PM alone did not stop the
storm.

Prevent the broken L0s configuration by removing L0s from the RTS525A
advertised ASPM capability.  This avoids enabling the non-working ASPM
state instead of masking the resulting AER Replay Timer Timeout reports.

Signed-off-by: Max Lee <max.lee@canonical.com>
---
Changes in v3:
  - Disable ASPM L0s for RTS525A instead of masking AER Replay Timer
    Timeout reports.
  - Keep ASPM L1 enabled based on testing that only L0s is required to
    reproduce the storm.
  - Drop the endpoint/root-port AER mask quirk from v2.

 drivers/pci/quirks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index caaed1a01dc0..e63ed055f466 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2520,6 +2520,9 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x10f1, quirk_disable_aspm_l0s);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x10f4, quirk_disable_aspm_l0s);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1508, quirk_disable_aspm_l0s);
 
+/* Realtek RTS525A generates Replay Timer Timeouts when L0s is enabled. */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_REALTEK, 0x525a, quirk_disable_aspm_l0s);
+
 static void quirk_disable_aspm_l0s_l1(struct pci_dev *dev)
 {
 	pcie_aspm_remove_cap(dev,
-- 
2.43.0