[PATCHv9 8/8] ARM: OMAP4: USB: power down MUSB PHY if not used

[Tero Kristo]

On Thu, 2012-10-18 at 16:53 +0300, Felipe Balbi wrote:
> hi,
> 
> On Thu, Oct 18, 2012 at 03:18:04PM +0300, Tero Kristo wrote:
> > > > +static int __init omap4430_phy_power_down(void)
> > > > +{
> > > > +	void __iomem *ctrl_base;
> > > > +
> > > > +	if (!cpu_is_omap44xx())
> > > > +		return 0;
> > > > +
> > > > +	ctrl_base = ioremap(OMAP443X_SCM_BASE, SZ_1K);
> > > > +	if (!ctrl_base) {
> > > > +		pr_err("control module ioremap failed\n");
> > > > +		return -ENOMEM;
> > > > +	}
> > > > +
> > > > +	/* Power down the phy */
> > > > +	__raw_writel(PHY_PD, ctrl_base + CONTROL_DEV_CONF);
> > > > +
> > > > +	iounmap(ctrl_base);
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +early_initcall(omap4430_phy_power_down);
> > > > +#endif
> > > 
> > > I think you could do it even if the driver is enabled.
> > 
> > Actually not at least now, it looks like the driver is not controlling
> > this bit at all, so the driver would fail if we do this.
> 
> then we can consider that a bug in the driver. Kishon, I thought you had
> added SCM address space to PHY driver for this particular reason until
> we get SCM driver, wasn't it ??

Yes, I would say its a bug in the driver. However we need this disable
mechanism for the case where we don't have the driver also (which is the
default config for omap.)

-Tero

> > > Just to make sure I understand the issue right: is the PHY enabled by
> > > default or did bootloader left this enabled ?
> > 
> > The reset value for the register is zero (at least according to TRM), so
> > it is enabled from boot. Also, I couldn't find any code from the u-boot
> > that would touch this bit with a quick look.
> 
> ok, so it looks like we must do this anyway, thanks ;-)
>