[PATCH v11 4/9] usb: chipidea: udc: add pullup/pulldown dp at hw_device_state

[balbi@ti.com (Felipe Balbi)]

Hi,

On Fri, Mar 08, 2013 at 09:28:34AM +0800, Peter Chen wrote:
> > > > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> > > > > index e82dae4..70f9f2d 100644
> > > > > --- a/drivers/usb/chipidea/udc.c
> > > > > +++ b/drivers/usb/chipidea/udc.c
> > > > > @@ -91,8 +91,10 @@ static int hw_device_state(struct ci13xxx *ci, u32 dma)
> > > > >  		/* interrupt, error, port change, reset, sleep/suspend */
> > > > >  		hw_write(ci, OP_USBINTR, ~0,
> > > > >  			     USBi_UI|USBi_UEI|USBi_PCI|USBi_URI|USBi_SLI);
> > > > > +		hw_write(ci, OP_USBCMD, USBCMD_RS, USBCMD_RS);
> > > > >  	} else {
> > > > >  		hw_write(ci, OP_USBINTR, ~0, 0);
> > > > > +		hw_write(ci, OP_USBCMD, USBCMD_RS, 0);
> > > > 
> > > > this patch doesn't make sense to me. What will happen is that you will
> > > > be enabling pullups when vbus_session() gets called and this might not
> > > > be what gadget driver wants.
> > > > 
> > > > You don't want to fiddle with that yourself since I'm changing the
> > > > framework so that gadget driver will always request pullups to be
> > > > enabled.
> > > 
> > > Hi Felipe,
> > > 
> > > Do you think pullup dp without vbus is a valid operation?
> > 
> > why not ? What I want to connect pullups first and only then issue SRP ?
> 
> I am not familiar with OTG, but it only stands for special case, right?

SRP is not OTG-specific. Any host is allowed to support it and any
device is allowed to initiate it.

> > > Current udc core code makes that possible.
> > 
> > so ?
> 
> Without vbus, but pullup dp, it will cause more power.

a fair concern.

> > > But I think current your udc core code (add pullup after loading
> > > gadget) make benefit for udc driver who has not vbus operation.
> > > 
> > > For chipidea driver:
> > > 
> > > - If vbus is there before load gadget module, the pullup dp is done by
> > > udc core code.
> > > - If vbus is not there before load gadget module, the pullup will be
> > > done when the vbus is there.
> > 
> > This isn't legal. If you want to make sure vbus is alive before
> > connecting pullups, then do it generically. Modify udc-core.c to make
> > those checks for you. Bypassing the framework is dangerous because
> > whenever I wanna change something, I might miss your private details and
> > end up causing regressions.
> 
> Let thing be generic is a good idea. Then, is it ok I post a patch let
> udc manage pullup by itself (through a flag) just you did for uvc?
> UDC core doesn't know VBUS, so the pullup can't be managed by udc core
> totally.

then teach UDC core about VBUS. Send the patches and we will figure out
if they can be applied or not.

> Besides, I looked four udc drivers (fsl_udc_core.c, at91_udc.c, mv_udc_core.c
> and bcm63xx_udc.c), the first three manage pullup by itself, ony
> bcm doesn't control it by itself.

those are all bugs that need to be sorted out. I don't have that HW so I
can't test any of my changes.

-- 
balbi
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