[SRU][unstabe/Q/P][PATCH 1/1] UBUNTU: SAUCE: PCI: Disable RRS polling for Intel SSDPE2KX020T8 nvme

[Hui Wang]

BugLink: https://bugs.launchpad.net/bugs/2111521

Prior to commit d591f6804e7e ("PCI: Wait for device readiness with
Configuration RRS"), this Intel nvme [8086:0a54] works well. Since
that patch is merged to the kernel, this nvme stops working.

Through debugging, we found that commit introduces the RRS polling in
the pci_dev_wait(), for this nvme, when polling the PCI_VENDOR_ID, it
will return ~0 if the config access is not ready yet, but the polling
expects a return value of 0x0001 or a valid vendor_id, so the RRS
polling doesn't work for this nvme.

Here we add a pci quirk to disable the RRS polling for the device.

Fixes: d591f6804e7e ("PCI: Wait for device readiness with Configuration RRS")
Signed-off-by: Hui Wang <hui.wang at canonical.com>
---
 drivers/pci/probe.c  |  3 ++-
 drivers/pci/quirks.c | 18 ++++++++++++++++++
 include/linux/pci.h  |  2 ++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3da48c13d9cc..2d1bebc1c159 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1265,7 +1265,8 @@ static void pci_enable_rrs_sv(struct pci_dev *pdev)
 	if (root_cap & PCI_EXP_RTCAP_RRS_SV) {
 		pcie_capability_set_word(pdev, PCI_EXP_RTCTL,
 					 PCI_EXP_RTCTL_RRS_SVE);
-		pdev->config_rrs_sv = 1;
+		if (!(pdev->dev_flags & PCI_DEV_FLAGS_NO_RRS_SV))
+			pdev->config_rrs_sv = 1;
 	}
 }
 
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 0d51c5d378da..530d669f92ec 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -6331,3 +6331,21 @@ static void pci_mask_replay_timer_timeout(struct pci_dev *pdev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_GLI, 0x9750, pci_mask_replay_timer_timeout);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_GLI, 0x9755, pci_mask_replay_timer_timeout);
 #endif
+
+/*
+ * Although the root port device claims to support RRS, some devices don't work
+ * with RRS polling, when reading the Vendor ID, they just return ~0 if config
+ * access is not ready, this will break the pci_dev_wait(). Here disable the RRS
+ * forcibly for this type of device.
+ */
+static void quirk_no_rrs_sv(struct pci_dev *dev)
+{
+	struct pci_dev *root;
+
+	root = pcie_find_root_port(dev);
+	if (root) {
+		root->dev_flags |= PCI_DEV_FLAGS_NO_RRS_SV;
+		root->config_rrs_sv = 0;
+	}
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x0a54, quirk_no_rrs_sv);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 255097538e19..7adb115bb419 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -247,6 +247,8 @@ enum pci_dev_flags {
 	PCI_DEV_FLAGS_HAS_MSI_MASKING = (__force pci_dev_flags_t) (1 << 12),
 	/* Device requires write to PCI_MSIX_ENTRY_DATA before any MSIX reads */
 	PCI_DEV_FLAGS_MSIX_TOUCH_ENTRY_DATA_FIRST = (__force pci_dev_flags_t) (1 << 13),
+	/* Do not use Configuration Request Retry Status polling in pci_dev_wait() */
+	PCI_DEV_FLAGS_NO_RRS_SV = (__force pci_dev_flags_t) (1 << 14),
 };
 
 enum pci_irq_reroute_variant {
-- 
2.34.1