Re: [PATCH 4/5] usb: ehci-hcd: use mdelay_non_inerruptible()

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Oct 07, 2015 at 07:52:21PM +0300, Peter Mamonov wrote:
> On Wed, 7 Oct 2015 17:40:24 +0200
> > > Non-interruptible delays are needed here to prevent ehci_* functions
> > > re-entrance. The re-entrance occurs during a usb bus scan, after
> > > detection of a usb keyboard. As soon as a USB keyboard is detected,
> > > it's driver starts the poller, which interferes with the process of
> > > usb bus scan. However that last one delay may be interruptible.
> > 
> > my problem is as soon as you start a usb control msg you block
> > everything
> > 
> > nothing else can run in barebox
> > 
> > can slow down barebox boot
> > 
> > I do think we need a real mdelay_non_interruptible feature but just
> > forbidden to recall usb control msg.
> > But the rest of barebox can run durring those 5ms
> 
> Well, I think it can be done by returning -EAGAIN on re-entrance
> detection in ehci_* functions [1], and skipping the poll in the keyboard
> driver.

Could you tell us what you have done to get re-entrance problems? I have
just replaced the mdelay_non_interruptible with regular mdelay in the
ehci driver and didn't notice any problems. Could you verify the
_non_interruptible is still needed?

Sascha

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