RE: [PATCH 2/6] usb: gadget: mv_udc: disable HW zlt for ep0

[Neil Zhang]

> -----Original Message-----
> From: Peter Chen [mailto:peter.chen@xxxxxxxxxxxxx]
> Sent: 2014年2月25日 9:19
> To: Neil Zhang
> Cc: balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 2/6] usb: gadget: mv_udc: disable HW zlt for ep0
> 
> On Mon, Feb 24, 2014 at 04:03:12PM +0800, Neil Zhang wrote:
> > Hardware zlt will try to send the zero length packet automatically
> > when the data transferd is multiple times of max packet, this will
> > cause issues on Windows.
> > So let's disable HW zlt by default.
> 
> Would you have description that what kinds of issue on Windows if zlt is is
> selected?
> 

Enumeration will fail.

> Peter
> 
> >
> > Signed-off-by: Neil Zhang <zhangwm@xxxxxxxxxxx>
> > ---
> >  drivers/usb/gadget/mv_udc_core.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/gadget/mv_udc_core.c
> > b/drivers/usb/gadget/mv_udc_core.c
> > index ebc0dfd..657ac5c 100644
> > --- a/drivers/usb/gadget/mv_udc_core.c
> > +++ b/drivers/usb/gadget/mv_udc_core.c
> > @@ -89,7 +89,7 @@ static void ep0_reset(struct mv_udc *udc)
> >  		/* configure ep0 endpoint capabilities in dQH */
> >  		ep->dqh->max_packet_length =
> >  			(EP0_MAX_PKT_SIZE << EP_QUEUE_HEAD_MAX_PKT_LEN_POS)
> > -			| EP_QUEUE_HEAD_IOS;
> > +			| EP_QUEUE_HEAD_IOS | EP_QUEUE_HEAD_ZLT_SEL;
> >
> >  		ep->dqh->next_dtd_ptr = EP_QUEUE_HEAD_NEXT_TERMINATE;
> >
> > --
> > 1.7.9.5
> >
> > --
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> >
> >
> 
> --
> 
> Best Regards,
> Peter Chen


Best Regards,
Neil Zhang
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