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From: Alan Stern <stern@rowland.harvard.edu>
To: John Donnelly <john.p.donnelly@oracle.com>
Cc: linux-usb@vger.kernel.org
Subject: Re: ehci-pci :   WARNING: CPU: 0 PID: 347 at kernel/dma/direct.c:34
Date: Sat, 28 Mar 2020 11:37:30 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.2003281135130.1088-100000@netrider.rowland.org> (raw)
In-Reply-To: <F5A0CCCB-4503-40B1-A24D-323F5B89C1F4@oracle.com>

On Fri, 27 Mar 2020, John Donnelly wrote:

> Hi,
> 
> I am seeing this WARNING event with iommu=off when booting a DL380
> server with a 5.4.17 kernel.

...

> The end result is this USB port is not configured when
> dma_direct_map_page() is called and it returns return
> DMA_MAPPING_ERROR;
> 
> 
> When I boot the server with iommu=on I don’t see  this sequence :

...

> On an older kernel  5.3. flavor I am not seeing this behavior, and the usbhib devices  appear as expected :

I forgot to mention: Since you have one kernel where the WARNING occurs 
and one where it doesn't, you can use bisection to find the commit that 
was responsible for the change in behavior.  If you care to go to the 
trouble...

Alan Stern


  parent reply	other threads:[~2020-03-28 15:37 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-28  4:11 ehci-pci : WARNING: CPU: 0 PID: 347 at kernel/dma/direct.c:34 John Donnelly
2020-03-28  7:08 ` Greg KH
2020-03-28 15:34 ` Alan Stern
2020-03-28 15:37 ` Alan Stern [this message]
2020-03-28 18:05   ` John Donnelly
2020-03-30 18:36   ` John Donnelly
2020-03-30 19:41     ` Alan Stern
2020-03-30 20:11       ` John Donnelly
2020-03-31  2:10         ` John Donnelly
2020-03-31 14:17           ` Alan Stern
2020-03-31 16:07             ` John Donnelly
2020-03-31 17:43               ` John Donnelly
2020-03-31 18:21                 ` Alan Stern
2020-04-07 13:49             ` John Donnelly
2020-04-07 13:53               ` Alan Stern

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