nvme device timeout

[Judy Brock-SSI]

Hi,


	>>We used to poll the drive for completions immediately after controller enable completed, so every command could have been polled. That was moved a little later in initialization in 4.5 (and removed entirely in 4.6 ...).

	>>  Removing the device from the pci topology might be a bit heavy handed. We really only need to unbind the driver in this case (will send a different patch).

Maybe I'm misunderstanding but unbinding the driver in this case instead of removing the driver from the PCI topology the device still doesn't achieve what polling for completions immediately after controller enable completes used to do, does it? I mean, identify will still fail in such cases without the polling. 

Why was that support removed and why not reinstate it?

Thanks,
Judy

-----Original Message-----
From: Linux-nvme [mailto:linux-nvme-bounces at lists.infradead.org] On Behalf Of Keith Busch
Sent: Monday, March 28, 2016 10:24 AM
To: Tim Mohlmann
Cc: linux-nvme at lists.infradead.org
Subject: Re: nvme device timeout

On Mon, Mar 28, 2016 at 07:44:20PM +0300, Tim Mohlmann wrote:
> Hi,
> 
> During boot my nvme device is not showing up. I've found the following 
> dmesg output from nvme:
> [    0.634251] nvme 0000:04:00.0: PCI INT A: no GSI
> [   61.703015] nvme 0000:04:00.0: I/O 0 QID 0 timeout, disable controller
> [   61.704028] nvme 0000:04:00.0: Identify Controller failed (-4)
> [   61.705016] nvme 0000:04:00.0: Removing after probe failure status: -5
> 
> lspci does not list device anymore.

Thanks for mentioning that. Removing the device from the pci topology might be a bit heavy handed. We really only need to unbind the driver in this case (will send a different patch).
 
> This problem occured after upgrading my kernel from 4.4.5 to 4.5-rc7.

I'll venture a guess that you were unknowingly relying on the driver's polling completion feature, and your controller doesn't support legacy irq.

We used to poll the drive for completions immediately after controller enable completed, so every command could have been polled. That was moved a little later in initialization in 4.5 (and removed entirely in 4.6 ...).

> I'm new to posting about bugs in the kernel, so please advise how I 
> can provide you with more meaningful info.

Could you apply the test patch below (created against 4.5-stable), and confirm if it still fails?

---
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 680f578..b9c989c 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1945,17 +1945,16 @@ static void nvme_reset_work(struct work_struct *work)
 	if (result)
 		goto out;
 
-	result = nvme_init_identify(&dev->ctrl);
+	dev->ctrl.event_limit = NVME_NR_AEN_COMMANDS;
+	result = nvme_dev_list_add(dev);
 	if (result)
 		goto out;
 
-	result = nvme_setup_io_queues(dev);
+	result = nvme_init_identify(&dev->ctrl);
 	if (result)
 		goto out;
 
-	dev->ctrl.event_limit = NVME_NR_AEN_COMMANDS;
-
-	result = nvme_dev_list_add(dev);
+	result = nvme_setup_io_queues(dev);
 	if (result)
 		goto out;
 
--

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