[PATCH v3 1/2] PCI: Ignore Immediate Readiness on Samsung 990 PRO NVMe

[Alexander Gruhlke <gruhlke@mailbox.org>]

The Samsung 990 PRO [144d:a80c] advertises Immediate Readiness, so
pcie_flr() doesn't wait after FLR, but the drive returns ~0 for up to
7 ms.  Since commit 10baa9b4df40 ("PCI: Drop unnecessary retries when
restoring BARs"), the config restore after FLR is lost, which breaks
VFIO passthrough of the drive.  Firmware 8B2QJXD7 responds right after
FLR, but older firmware such as 1B2QJXD7 doesn't, and the firmware
version isn't visible here.

Ignore Immediate Readiness on this device, so pcie_flr() waits.

Fixes: 10baa9b4df40 ("PCI: Drop unnecessary retries when restoring BARs")
Link: https://bbs.archlinux.org/viewtopic.php?id=314833
Link: https://lore.kernel.org/r/20261010160529.27974-1-gruhlke@mailbox.org
Suggested-by: Lukas Wunner <lukas@wunner.de>
Assisted-by: Claude:claude-opus-5-5
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Alexander Gruhlke <gruhlke@mailbox.org>
---
 drivers/pci/quirks.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 0500d5fd4f..e8597d1209 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5623,6 +5623,17 @@ static void quirk_no_flr_snet(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SOLIDRUN, 0x1000, quirk_no_flr_snet);
 
+/* Samsung 990 PRO advertises Immediate Readiness, but isn't ready after FLR */
+static void quirk_no_imm_ready(struct pci_dev *dev)
+{
+	if (!dev->imm_ready)
+		return;
+
+	pci_info(dev, "Ignoring incorrectly advertised Immediate Readiness support\n");
+	dev->imm_ready = 0;
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_SAMSUNG, 0xa80c, quirk_no_imm_ready);
+
 static void quirk_no_ext_tags(struct pci_dev *pdev)
 {
 	struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
-- 
2.56.0