Re: [PATCH] PCI: pciehp: Ignore Link Down/Up caused by DPC

[Lukas Wunner <lukas@wunner.de>]

On Wed, Apr 28, 2021 at 06:08:02PM +0800, Yicong Yang wrote:
> I've tested the patch on our board, but the hotplug will still be
> triggered sometimes.
> seems the hotplug doesn't find the link down event is caused by dpc.
> Any further test I can do?
> 
> mestuary:/$ [12508.408576] pcieport 0000:00:10.0: DPC: containment event, status:0x1f21 source:0x0000
> [12508.423016] pcieport 0000:00:10.0: DPC: unmasked uncorrectable error detected
> [12508.434277] pcieport 0000:00:10.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Completer ID)
> [12508.447651] pcieport 0000:00:10.0:   device [19e5:a130] error status/mask=00008000/04400000
> [12508.458279] pcieport 0000:00:10.0:    [15] CmpltAbrt              (First)
> [12508.467094] pcieport 0000:00:10.0: AER:   TLP Header: 00000000 00000000 00000000 00000000
> [12511.152329] pcieport 0000:00:10.0: pciehp: Slot(0): Link Down

Note that about 3 seconds pass between DPC trigger and hotplug link down
(12508 -> 12511).  That's most likely the 3 second timeout in my patch:

+	/*
+	 * Need a timeout in case DPC never completes due to failure of
+	 * dpc_wait_rp_inactive().
+	 */
+	wait_event_timeout(dpc_completed_waitqueue, dpc_completed(pdev),
+			   msecs_to_jiffies(3000));

If DPC doesn't recover within 3 seconds, pciehp will consider the
error unrecoverable and bring down the slot, no matter what.

I can't tell you why DPC is unable to recover.  Does it help if you
raise the timeout to, say, 5000 msec?

Thanks,

Lukas