[Bug 214789] ehci-hcd.c ISR

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=214789

--- Comment #14 from Scott Arnold (scott.c.arnold@nasa.gov) ---
Hello,
Sorry for the confusion.
While patching echi-hcd.c using meld to change spin_locks " current_status =
ehci_readl(ehci, &ehci->regs->status);" got changed to "status =
ehci_readl(ehci, &ehci->regs->status);" (~line 723).
As a result current_status was used un-initialized (I would have thought gcc
8.3.1 would have warned about that).
This caused the "nobody cared" messages on IRQ's 16 and 23. So ehci-hcd did not
load/allocate the IRQ's.
Spin_locks are not the problem.
If ehci-hcd does not load the timer card works fine.
If ehci-hcd loads the timer card will not work even if ehci-hcd is unloaded.
IRQ count on 16 stuck at ~90 in /proc/interrupts.
Seems like IRQ 16 is somehow left disabled. Could be why uhci-hcd does not load
?
All works fine with the 5.3.6 kernel, broken in 5.11+.

Lsudb with 5.3.6:

Bus 002 Device 003: ID 0424:2660 Microchip Technology, Inc. (formerly SMSC) Hub
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 14dd:1007 Raritan Computer, Inc. D2CIM-VUSB KVM
connector
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Thanks
Scott

-----Original Message-----
From: bugzilla-daemon@bugzilla.kernel.org <bugzilla-daemon@bugzilla.kernel.org> 
Sent: Tuesday, October 26, 2021 9:06 PM
To: Arnold, Scott C. (JSC-CD13)[SGT, INC] <scott.c.arnold@nasa.gov>
Subject: [EXTERNAL] [Bug 214789] ehci-hcd.c ISR

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--- Comment #13 from Alan Stern (stern@rowland.harvard.edu) --- What does the
kernel log from a recent kernel say about UHCI?  If it is present in the older
kernel then it should still show up in the recent kernel.

And if the problem is related to uhci-hcd, why would patching ehci-hcd make it
go away?

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