[PATCH v4] 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.

For example:

  pcieport 0000:00:1c.6: AER: Multiple Correctable error message received from 0000:58:00.0
  rtsx_pci 0000:58:00.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Transmitter ID)
  rtsx_pci 0000:58:00.0:   device [10ec:525a] error status/mask=00001000/00006000
  rtsx_pci 0000:58:00.0:    [12] Timeout
  pcieport 0000:00:1c.6: AER: Correctable error message received from 0000:58:00.0

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.

Reviewed-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Max Lee <max.lee@canonical.com>
---
Changes in v4:
  - Add an AER log snippet to make the quirk easier to find.
  - Reword the RTS525A comment to describe this as a Replay Timer Timeout storm.
  - Add Reviewed-by tags from Lukas Wunner and Manivannan Sadhasivam.
  - Add Cc stable tag as suggested by Lukas Wunner.

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

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index caaed1a01dc0..ab94bd7f3a34 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 a Replay Timer Timeout storm 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