Re: [PATCH] usb: ehci: Prevent missed ehci interrupts with edge-triggered MSI

[Alan Stern <stern@rowland.harvard.edu>]

On Wed, Jul 14, 2021 at 12:10:26PM -0400, David Jeffery wrote:
> On Wed, Jul 14, 2021 at 10:29 AM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > Does this issue affect any other PCI-based host controller drivers?
> >
> > Alan Stern
> >
> 
> Possibly.  The uhci driver should have the same issue if hardware
> exists with it and has MSI for it.  I suspect the ohci driver has a
> similar issue, but I'm not familiar enough with its interfaces and
> specification to say for sure.

Hmmm.  I've never heard of an MSI implementation of either of those, 
although it may be possible for OHCI.  UHCI was used only by Intel and 
one or two others; as far as I know none of them are producing those 
controllers any more.  Nowadays when people want to support USB-1.1 
devices but not USB-3, they use an EHCI controller together with a 
"rate-matching" hub, which avoids the need for any UHCI or OHCI 
controller.

I was wondering more about dwc2 or other non-EHCI USB-2 controller 
drivers.

Alan Stern