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List:       linux-usb-devel
Subject:    Re: [linux-usb-devel] EHCI & OHCI interrupt weirdness
From:       Jesse Barnes <jbarnes () sgi ! com>
Date:       2005-01-19 17:51:32
Message-ID: 200501190951.32775.jbarnes () sgi ! com
[Download RAW message or body]

On Tuesday, January 18, 2005 5:39 pm, David Brownell wrote:
> > Does it matter which driver I load first, ehci or ohci?
>
> I recommend EHCI first, to minimize resetting of USB devices during
> initialization and simplify the PM resume scenarios.  Other than
> that issue, it's not supposed to matter.

 66:          0       4407          0          0          SN hub  ohci_hcd
 67:          0        517          0          0          SN hub  ohci_hcd, 
ehci

[Above is after loading ohci first--a working setup.  If I load ehci first, 
irq 66 spins out of control and is eventually shut off by the kernel because 
of too many IRQ_NONE returns.]

How is this supposed to work?  I've just tested again and things work ok as 
long as I load ohci first.  The interrupts seem to be getting assigned 
correctly by the BIOS (there are supposed to be two of them, right?), but it 
looks like if ehci registers its interrupt handler first, it just returns 
IRQ_NONE, causing hcd_irq to not handle irq 66, which is apparently the usb 
1.1 ohci controller.

Thanks,
Jesse


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