Re: [PATCH v3 0/5] Add support for SW babble Control

[George Cherian]

Hi Daniel,

On 5/13/2014 6:44 PM, Daniel Mack wrote:
> Hi George,
>
> On 05/13/2014 02:57 PM, George Cherian wrote:
> > I never enabled the MUSB_BABBLE_SW_SESSION_CTRL in the MUSB_BABBLE_CTL reg.
> > can you try with the following patch.
> >
> > diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
> > index 1ae6681..1160cd1 100644
> > --- a/drivers/usb/musb/musb_dsps.c
> > +++ b/drivers/usb/musb/musb_dsps.c
> > @@ -477,8 +477,11 @@ static int dsps_musb_init(struct musb *musb)
> >    	 * logic enabled.
> >    	 */
> >    	val = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
> > -	if (val == MUSB_BABBLE_RCV_DISABLE)
> > +	if (val == MUSB_BABBLE_RCV_DISABLE) {
> >    		glue->sw_babble_enabled = true;
> > +		val |= MUSB_BABBLE_SW_SESSION_CTRL;
> > +	        dsps_writeb(musb->mregs, MUSB_BABBLE_CTL, val);
> > +	}
> >    
> >    	ret = dsps_musb_dbg_init(musb, glue);
> >    	if (ret)
> MUSB_BABBLE_STUCK_J still remains unset, so I get the same result as
> without the patch: a full glue reset is conducted. Do I get you right
> that you expect MUSB_BABBLE_STUCK_J to be set in babble conditions when
> MUSB_BABBLE_SW_SESSION_CTRL is set?
Basically, there are 2 types of babble conditions.
1) Transient babble condition - which could be recovered from without an 
IP reset .
2) Babble condition - which could be recovered from only by doing an IP 
reset.

Looks like you are always hitting case 2 (Most times am also hitting the 
same).
Case 1 is really hard to reproduce. I don't have a reliable method as of 
now to
reproduce this case consistently.
> [   19.672373] CAUTION: musb: Babble Interrupt Occurred
> [   19.677776] musb_stage0_irq 789: unhandled DISCONNECT transition
> (a_wait_bcon)
> [   19.685815] usb 1-1: USB disconnect, device number 3
> [   19.769720] musb-hdrc musb-hdrc.0.auto: babble: MUSB_BABBLE_CTL value 44
> [   19.776765] musb-hdrc musb-hdrc.0.auto: STUCK_J is reset
>
>
> I don't quite follow, especially as I lack documentation of the IP core.
> How do you test babble errors, is there any way to force them to happen
> reliably?

There is no 100% reliable method to force it to happen. Following is
my setup ,
I have a HUB with 4 devices connected , which gives me a Babble interrupt
on both connects and disconnects ( Not always though).
> Anyway, the full glue layer solves this rare condition quite well for
> me. Is there any downside of this?
>
>
> Daniel


--
-George

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