linux-kernel - RE: [PATCH v1 2/3] usb: musb: core: added babble recovery func-ptr to musb->ops

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Date:	Wed, 26 Jun 2013 08:37:39 +0000
From:	"B, Ravi" <ravibabu@...com>
To:	"Balbi, Felipe" <balbi@...com>
CC:	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v1 2/3] usb: musb: core: added babble recovery func-ptr
 to musb->ops

Felipe

> 
> On Wed, May 29, 2013 at 06:37:03PM +0530, Ravi Babu wrote:
> > Adding babble_recovery operation as part of musb->ops, used to recover
> > from babble condition during babble interrupt.
> >
> > Signed-off-by: Ravi Babu <ravibabu@...com>
> > ---
> >  drivers/usb/musb/musb_core.c |    6 ++++++
> >  drivers/usb/musb/musb_core.h |    7 +++++++
> >  2 files changed, 13 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/usb/musb/musb_core.c
> > b/drivers/usb/musb/musb_core.c index ab6fa39..411c29d 100644
> > --- a/drivers/usb/musb/musb_core.c
> > +++ b/drivers/usb/musb/musb_core.c
> > @@ -857,6 +857,12 @@ b_host:
> >  		}
> >  	}
> >
> > +	/* handle babble condition */
> > +	if (int_usb & MUSB_INTR_BABBLE) {
> > +		pr_info("babble: restarting the musb controller..");
> > +		musb_babble_recovery(musb);
> > +	}
> > +
> >  #if 0
> >  /* REVISIT ... this would be for multiplexing periodic endpoints, or
> >   * supporting transfer phasing to prevent exceeding ISO bandwidth
> > diff --git a/drivers/usb/musb/musb_core.h
> > b/drivers/usb/musb/musb_core.h index f96e899..bf37dc9 100644
> > --- a/drivers/usb/musb/musb_core.h
> > +++ b/drivers/usb/musb/musb_core.h
> > @@ -213,6 +213,8 @@ struct musb_platform_ops {
> >  	int	(*adjust_channel_params)(struct dma_channel *channel,
> >  				u16 packet_sz, u8 *mode,
> >  				dma_addr_t *dma_addr, u32 *len);
> > +
> > +	void	(*babble_recovery)(struct musb *musb);
> 
> I don't get why can't 'babble_recovery' be generic. Why do we need each glue
> layer to implement it ?
> 

Babble is generic, but recovery mechanism is nothing but "reset of usbss" which is SoC dependent and followed by generic restart of the musb controller. 
That is why musb_restart() API is exported used by all glue in babble recovery.

--
Ravi B
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