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From: Scott Wood <oss@buserror.net>
To: Darren Stevens <darren@stevens-zone.net>
Cc: Christian Zigotzky <chzigotzky@xenosoft.de>, linuxppc-dev@lists.ozlabs.org
Date: Wed, 29 Aug 2018 18:30:10 -0500
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Subject: Re: FSL/NXP P5020: USB problems with the latest Git kernels
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On Tue, 2018-08-28 at 20:13 +0100, Darren Stevens wrote:
> Hello Scott
> 
> On 27/08/2018, Scott Wood wrote:
> > On Mon, 2018-08-27 at 20:15 +0200, Christian Zigotzky wrote:
> > > Hello,
> > > 
> > > Our users tested the RC1 of kernel 4.19 on their P5020 boards today.
> > > Unfortunately the USB bug still exists. With mem values bigger than
> > > 4096M,
> > > the USB mouse and keyboard doesn't work. With the bootarg mem=4096M, the
> > > USB
> > > devices work without any problems. Please compile the RC1 and test it on
> > > your P5020 board. There is a problem with the memory management since
> > > 22/08/18. 
> > 
> > I just tested 4.19-rc1 on a T4240 and got a similar problem with MMC.  MMC
> > and
> > USB on these chips both have a 32-bit DMA limitation.  I'll look into it.
> 
> I've run a bisect locally on my system and found the following bad commit:
> 
> # first bad commit: [1b1eeca7e4c19fa76d409d4c7b338dba21f2df45] init: allow
> initcall tables to be emitted using relative references
> 
> I can't see why this would fail though, and it only seems to affect fsl
> machines, and on mine it killed the onboard sata as well.
> 
> Hope this helps.


The patch is changing the order of initcalls.  swiotlb_setup_bus_notifier()
and corenet_gen_publish_devices() are both machine_arch_initcall(), and if the
latter happens before the former, then the bus notifier gets missed and
swiotlb doesn't get used.

-Scott