[PATCH v12 06/13] usb: chipidea: add otg_cap attribute for otg capable

[Alexander Shishkin]

Peter Chen <peter.chen at freescale.com> writes:

> On Fri, Jul 12, 2013 at 11:12:01AM +0300, Alexander Shishkin wrote:
>> Peter Chen <peter.chen at freescale.com> writes:
>> 
>> > Since we need otgsc to know vbus's status at some chipidea
>> > controllers even it is peripheral-only mode. Besides, some
>> > SoCs (eg, AR9331 SoC) don't have otgsc register even
>> > the DCCPARAMS_DC and DCCPARAMS_HC are both 1 at CAP_DCCPARAMS.
>> > We inroduce otg_cap attribute to indicate if the controller
>> > is otg capable, defaultly, we follow the rule that if DCCPARAMS_DC
>> > and DCCPARAMS_HC are both 1 at CAP_DCCPARAMS are otg capable, but if there
>> > is exception, the platform can override it by device tree or platform data.
>> >
>> > Signed-off-by: Peter Chen <peter.chen at freescale.com>
>> > ---
>> 
>> [...]
>> 
>> > diff --git a/include/linux/usb/chipidea.h b/include/linux/usb/chipidea.h
>> > index 118bf66..0a906b4 100644
>> > --- a/include/linux/usb/chipidea.h
>> > +++ b/include/linux/usb/chipidea.h
>> > @@ -7,6 +7,12 @@
>> >  
>> >  #include <linux/usb/otg.h>
>> >  
>> > +enum usb_otg_cap {
>> > +	OTG_CAP_ATTR_IS_NOT_EXISTED = 0,
>> > +	OTG_CAP_ATTR_IS_TRUE,
>> > +	OTG_CAP_ATTR_IS_FALSE,
>> > +};
>> 
>> We don't really need all three, do we? We only need to know if the
>> controller *can't* do otg. The rest we can infer from dr_mode and
>> DCCPARAMS. So it can be another bit in flags rather than a separate
>> field in platdata.
>> 
>
> In order to cover below two cases, I have no other idea.
>
> 1. For mips Soc (ARxxx), if dr_mode = otg and it is 1 for both
> mode at DCCPARAMS,  It can switch role through proc or whatever,
> but NO otgsc register, it is NOT otg-capable.

For this case, platform should set

platdata->flags &= CI_HDRC_NO_OTG

, which will set ci->is_otg = false. No ci->is_otg => no touching
OTGSC.

> 2. For peripheral-only case at most chipidea controllers,
> the dr_mode = peripheral and it is 1 for both modes at DCCPARAMS,
> the otgsc can be visited, it is otg-capable.

Then platform *doesn't* set CI_HDRC_NO_OTG and ci->is_otg is set to
true, because DCCPARAMS.DC==1 and DCCPARAMS.HC==1, but we only have one
role initialized, because of dr_mode==peripheral, so no role switching
happens, but OTGSC accesses are fine.

Makes sense?

Regards,
--
Alex