[U-Boot] [PATCH 3/3] imx: mx6sllevk: add usb support

[Peng Fan]

> >>>>>>>>> +#define USB_OTHERREGS_OFFSET   0x800
> >>>>>>>>> +#define UCTRL_PWR_POL          (1 << 9)
> >>>>>>>>> +
> >>>>>>>>> +int board_ehci_hcd_init(int port) {
> >>>>>>>>> +	u32 *usbnc_usb_ctrl;
> >>>>>>>>> +
> >>>>>>>>> +	if (port > 1)
> >>>>>>>>> +		return -EINVAL;
> >>>>>>>>> +
> >>>>>>>>> +	usbnc_usb_ctrl = (u32 *)(USB_BASE_ADDR +
> >>>> USB_OTHERREGS_OFFSET
> >>>>>>>> +
> >>>>>>>>> +				 port * 4);
> >>>>>>>>> +
> >>>>>>>>> +	/* Set Power polarity */
> >>>>>>>>> +	setbits_le32(usbnc_usb_ctrl, UCTRL_PWR_POL);
> >>>>>>>>> +	return 0;
> >>>>>>>>> +}
> >>>>>>>>
> >>>>>>>> Is this function similar to what usb_oc_config() does ?
> >>>>>>>
> >>>>>>> No, this bit is not for overcurrent. According to RM, this is
> >>>>>>> OTG Power Polarity This bit should be set according to power
> >>>>>>> switch's enable
> >>>>>> polarity.
> >>>>>>> 1 Power switch has an active-high enable input
> >>>>>>> 0 Power switch has an active-low enable input
> >>>>>>>
> >>>>>>> This is board specific.
> >>>>>>
> >>>>>> Great, except it should also be part of the driver , the same way
> >>>>>> as polarity is configured, yes ?
> >>>>>
> >>>>> I just found that there is code for mx7,
> >>>>> http://lists.denx.de/pipermail/u-boot/2016-July/260321.html
> >>>>>
> >>>>> Then do you agree I add such piece code in usb_power_config for mx6?
> >>>>> "
> >>>>> #ifdef CONFIG_MXC_USB_OTG_HACTIVE
> >>>>>         setbits_le32(ctrl, UCTRL_PWR_POL); #else
> >>>>>         clrbits_le32(ctrl, UCTRL_PWR_POL); #endif "
> >>>>
> >>>> Didn't you add DT support in a patch sent like ... yesterday ? :)
> >>>> Just use DT property instead of ifdef.
> >>>
> >>> There is no property for otg power polatiry in upstream Linux. I
> >>> would not like to introduce one in U-Boot. We can drop the ifdef
> >>> when there is an
> >> property in upstream. What do you think?
> >>
> >> So uh, how can the USB work in mainline Linux on that board ?
> >
> > Confirmed with IC, if using gpio to control vbus power, no need to configure
> this bit.
> > Since in dts, we are using gpio regulator to control vbus, this piece
> > code in patch 3/3 can be discarded. I'll drop it in V2.
> 
> Hum, OK. Let's revisit this when we need this then ?

Take i.MX6SLL as an example,
The pin key_col4 can be configured with the two functions.
[1] MX6_PAD_KEY_COL4__USB_OTG1_PWR 
[2] MX6_PAD_KEY_COL4__GPIO4_IO00

In fsl i.mx uboot code, the common way is to use [1] and configure the polarity to enable the vbus power.
But in kernel, it is configured as [2] and use gpio regulator to enable the vbus power.

This is board specific. There is no upstream property for this bit. When there is an upstream property for this,
We could add it in probe function for those that use [1] in dts pinmux.

Now I am using the same dts from kernel which this pinmux configured as [2], so this piece code is not needed for now.

Thanks,
Peng.
> 
> --
> Best regards,
> Marek Vasut