[PATCH v2 05/11] USB: chipidea: don't let probe fail if otg controller start one role failed

[Alexander Shishkin]

Richard Zhao <richard.zhao at freescale.com> writes:

> On Wed, Aug 29, 2012 at 12:48:15PM +0300, Alexander Shishkin wrote:
>> Richard Zhao <richard.zhao at freescale.com> writes:
>> 
>> > On Wed, Aug 29, 2012 at 11:10:33AM +0300, Alexander Shishkin wrote:
>> >> Richard Zhao <richard.zhao at freescale.com> writes:
>> >> 
>> >> > On Tue, Aug 28, 2012 at 11:38:23AM +0300, Alexander Shishkin wrote:
>> >> >> Richard Zhao <richard.zhao at freescale.com> writes:
>> >> >> 
>> >> >> > One role failed, but the other role will possiblly still work.
>> >> >> > For example, when udc start failed, if plug in a host device,
>> >> >> > it works.
>> >> >> 
>> >> >> If you're a host device, ci->role should be HOST at this point and
>> >> >> ci_role_start() shouldn't fail. If ci->role is detected wrongly, the
>> >> >> role detection must be fixed. If ci_role_start() fails for host, but it
>> >> >> still works when it's called again after the id pin change is detected,
>> >> >> again, the problem is elsewhere.
>> >> > The check is only for OTG device. For single role device, it just fail
>> >> > if it start the role failed.
>> >> 
>> >> Sorry, can you rephrase?
>> >> 
>> >> >> 
>> >> >> >
>> >> >> > Signed-off-by: Richard Zhao <richard.zhao at freescale.com>
>> >> >> > ---
>> >> >> >  drivers/usb/chipidea/core.c |    7 +++++--
>> >> >> >  1 file changed, 5 insertions(+), 2 deletions(-)
>> >> >> >
>> >> >> > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
>> >> >> > index 19ef324..8fd390a 100644
>> >> >> > --- a/drivers/usb/chipidea/core.c
>> >> >> > +++ b/drivers/usb/chipidea/core.c
>> >> >> > @@ -473,8 +473,11 @@ static int __devinit ci_hdrc_probe(struct platform_device *pdev)
>> >> >> >  	ret = ci_role_start(ci, ci->role);
>> >> >> >  	if (ret) {
>> >> >> >  		dev_err(dev, "can't start %s role\n", ci_role(ci)->name);
>> >> >> > -		ret = -ENODEV;
>> >> >> > -		goto rm_wq;
>> >> >> > +		ci->role = CI_ROLE_END;
>> >> >> 
>> >> >> So are you relying on id pin interrupt for initializing the role after
>> >> >> this? Can you provide more details?
>> >> > Yes. The ID pin detect still works. My case is, gadget role failed,
>> >> > host role works. I was trying not to ruin host function.
>> >> 
>> >> But it shouldn't even try to start the gadget, because ci_otg_role()
>> >> should set ci->role to HOST before ci_role_start() happens.
>> > It depends on ID pin. If ID pin is gadget and gadget is not support well,
>> > ci_role_start will fail. See below example.
>> >> 
>> >> Another question is, why does gadget start fail?
>> > There's one example:
>> > If usb phy don't support otg yet, otg_set_peripheral will fail, and
>> > then cause udc_start fail.
>> 
>> So you should drop the CI13XXX_REQUIRE_TRANSCEIVER flag from imx
>> platform data till the phy is fully implemented.
> It's just an example. We can not assume udc_start always success. If it
> fails, isn't it better to continue support of host than say game over?

Ok, I think what we need here is to rework error handling around role
switching, so that we can allow certain things to fail and retry at a
later point (say at id pin change), while being careful about the other
failures.

If this patch is not crucial for imx right now, I'd prefer to leave it
out.

Regards,
--
Alex