RE: [PATCH 1/2 v2] musb: Add context save and restore support

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Hi,
> -----Original Message-----
> From: Dasgupta, Romit
> Sent: Thursday, November 26, 2009 2:33 PM
> To: Gupta, Ajay Kumar
> Cc: linux-usb@xxxxxxxxxxxxxxx; linux-omap@xxxxxxxxxxxxxxx;
> felipe.balbi@xxxxxxxxx; Gadiyar, Anand
> Subject: Re: [PATCH 1/2 v2] musb: Add context save and restore support
> 
> > --- a/drivers/usb/musb/musb_core.c
> > +++ b/drivers/usb/musb/musb_core.c
> > @@ -2167,21 +2167,163 @@ static int __devexit musb_remove(struct
> platform_device *pdev)
> >
> >  #ifdef CONFIG_PM
> >
> > +static struct musb_context_registers musb_context;
> > +
> > +void musb_save_context(void __iomem *musb_base)
> > +{
> > +       int i;
> > +
> > +       musb_context.faddr = musb_readb(musb_base, MUSB_FADDR);
> > +       musb_context.power = musb_readb(musb_base, MUSB_POWER);
> > +       musb_context.intrtxe = musb_readw(musb_base, MUSB_INTRTXE);
> > +       musb_context.intrrxe = musb_readw(musb_base, MUSB_INTRRXE);
> > +       musb_context.intrusbe = musb_readb(musb_base, MUSB_INTRUSBE);

> > +       musb_context.frame = musb_readw(musb_base, MUSB_FRAME);
> Not necessary for gadget
> > +       musb_context.testmode = musb_readb(musb_base, MUSB_TESTMODE);
> Not sure if it is necessary for gadget.

Right!

..so we can all #ifdefs to save/restore gadget or host only registers.
 

> > +       musb_context.index = musb_readb(musb_base, MUSB_INDEX);
> 
> 
<snip>
> > +                               musb_read_txfifosz(musb_base);
> > +               musb_context.index_regs[i].rxfifosz =
> > +                               musb_read_rxfifosz(musb_base);
> 
> If MUSB_CONFIGDATA_DYNFIFO is not set then saving FIFO address and sizes
> are probably not necessary. Not sure if they are detrimental as well.

We can add it within DYNFIFO check.

> > +
> > +               musb_context.index_regs[i].txfunaddr =
> > +                       musb_read_txfunaddr(musb_base, i);
> > +               musb_context.index_regs[i].txhubaddr =

<snip.>

> >                  */
> > +               reg = musb_readb(musb->mregs, MUSB_POWER);
> > +               reg &= ~MUSB_POWER_SOFTCONN;
> > +               musb_writeb(musb->mregs, MUSB_POWER, reg);
> After this softdisconnect when we subsequently get reconnected followed by
> a reset we could have changed our speed (LS,FS, HS).

I didn't get it completely. I think as a peripheral USB speed will remain
same after resume for the gadget driver it was before suspend?

If we intend to change the gadget driver then we may have support for a
different speed but it would anyways happen after resume is completed.

Regards,
Ajay
> In your resume 
> routine we are writing back our previous speed. I am not sure here but is 
> it not possible that we have reset the controller and then restored back 
> the old speed overwriting the new speed?




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