RPI 4B on UEFI: xhci0 disconnects under high load

[Robert Clausecker]

Hi Mark,

On Fri, Sep 25, 2020 at 10:08:41AM -0700, Mark Millard wrote:
> 
> 
> On 2020-Sep-25, at 03:39, Robert Crowston <crowston at protonmail.com> wrote:
> 
> > Could the failure of the ACPI patch to work be related to the
> pre-September 2020 dtbs reporting 4 GB available for pci DMA
> (as you reported today in another thread)?
> > 
> 
> I'm unclear if you are specifically referring to:
> 
> A) this thread's "disconnects under high load" failures?
> B) the huge file duplication and diff/cmp test failures?
> C) both?
> D) even more?
> 
> For (A) I'd not conclude much until results are in for
> FreeBSD that is head -r365918 or later. It might be a
> fixed problem.

I've rebuild a kernel based on github revision e77e27fa:

    pwm(8): fix potential duty overflow, use unsigneds for period and duty

Not sure what the revision number of that one is.  The only
patch I applied is D25219 as the others don't cleanly apply.
The xhci disconnection error did not occur again.  I'll check
if this also fixes the problem that I wasn't able to boot from
a disk attached to a USB 3.0 boot, but right now I don't have
physical access to the machine, so it'll have to wait.

Note that this was without the RAM size limiter on.  Maybe I
didn't generate enough load for this to be an issue.

> For (B), I've been reporting examples of the issue since
> 2020-Jun-21 using rpi4-uefi-devel v1.16 and head -r360311 .
> But my most recent reports are based on the modern dtb that
> has 3 GiByte for the size of the range (uefi v1.20 and its
> bundled RPI4B materials or newer raspberry pi materials)
> and head -r365932. So both old and new got the same type
> of failures. (I've not tested materials from prior to
> 2020-Jun-21 with > 3072 MiByte in this way: that is when
> I discovered the test.)
> 
> Does that answer your question?
> 
> ===
> Mark Millard
> marklmi at yahoo.com
> ( dsl-only.net went
> away in early 2018-Mar)

Yours,
Robert Clausecker

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