Re: [PATCHv2] usb: musb: Fix unbalanced platform_disable

[Andreas Kemnade <andreas-cLv4Z9ELZ06ZuzBka8ofvg@public.gmane.org>]

On Mon, 12 Sep 2016 10:34:08 -0700
Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org> wrote:

> * Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org> [160912 10:26]:
> > * Bin Liu <b-liu-l0cyMroinI0@public.gmane.org> [160912 09:55]:
> > > Hi Tony,
> > > 
> > > On Mon, Sep 12, 2016 at 08:39:49AM -0700, Tony Lindgren wrote:
> > > > Commit a83e17d0f73b ("usb: musb: Improve PM runtime and phy
> > > > handling for 2430 glue layer") moved PHY enable/disable calls
> > > > to happen from omap2430_musb_enable/disable(). That broke
> > > > enumeration for several devices as PM runtime in the PHY will
> > > > never enable it.
> > > > 
> > > > The root cause of the problem is unpaired calls from
> > > > musb_core.c to musb_platform_enable/disable in musb_core.c as
> > > > reported by Andreas Kemnade <andreas-cLv4Z9ELZ06ZuzBka8ofvg@public.gmane.org>.
> > > > 
> > > > As musb_platform_enable/disable are being called from various
> > > > functions, let's not attempt to make them paiered immediately.
> > > > This would require fixing all the callers like musb_remove.
> > > > 
> > > > Instead, let's first fix the regression in a minimal way by
> > > > removing the initial call to musb_platform_disable.
> > > > 
> > > > AFAIK the initial musb_platform_disable call has always been
> > > > just an attempted workaround for the 2430 glue layer announcing
> > > > itself too early before the gadgets are configured. And that
> > > > issue finally
> > > 
> > > Many glue layers rely on musb_platform_diable to disable
> > > interrupts in musb_init_controller() before registering ISR, is
> > > it safe to assume the interrupts will be masked when musb is
> > > out-of-reset so that we don't have to call
> > > musb_platform_disable() in musb_init_controller()?
> > 
> > It should be, we do request_irq only later on after this in
> > musb_core.c. And the glue layers don't do request_irq except for
> > the separate DMA interrupts in two cases.
> > 
> > And as the platform glue layer are the ones doing the probing, they
> > should initialize things into sane state :)
> > 
> > We could add a call irq_set_status_flags(irq, IRQ_NOAUTOEN) before
> > request_irq. But I'm guessing there's no need to.. Do you have some
> > example in mind that should be tested?
> 
> Oh I see davinci_musb_disable and am35x_musb_disable reset devctl and
> clear interrupts. I'll try to check on am3517 here today, don't have
> any davinci boards configured here.
> 
Hmm, then the question is: Couldn't the X_musb_disable simply be called
from X_probe if needed to be an the safe side?

Regards,
Andreas
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