[PATCH AUTOSEL 5.4 4/7] nvme-pci: add trouble shooting steps for timeouts

[Sasha Levin]

From: Keith Busch <kbusch@xxxxxxxxxx>

[ Upstream commit 4641a8e6e145f595059e695f0f8dbbe608134086 ]

Many users have encountered IO timeouts with a CSTS value of 0xffffffff,
which indicates a failure to read the register. While there are various
potential causes for this observation, faulty NVMe APST has been the
culprit quite frequently. Add the recommended troubleshooting steps in
the error output when this condition occurs.

Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/nvme/host/pci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 10fe7a7a2163..df3b93e190e8 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1266,6 +1266,14 @@ static void nvme_warn_reset(struct nvme_dev *dev, u32 csts)
 		dev_warn(dev->ctrl.device,
 			 "controller is down; will reset: CSTS=0x%x, PCI_STATUS read failed (%d)\n",
 			 csts, result);
+
+	if (csts != ~0)
+		return;
+
+	dev_warn(dev->ctrl.device,
+		 "Does your device have a faulty power saving mode enabled?\n");
+	dev_warn(dev->ctrl.device,
+		 "Try \"nvme_core.default_ps_max_latency_us=0 pcie_aspm=off\" and report a bug\n");
 }
 
 static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
-- 
2.35.1