linux-kernel - Re: [PATCH 4/6] usb: gadget: add functions to signal udc driver to delay status stage

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Message-ID: <3055233.Lvy0NcWSZ5@avalon>
Date:   Thu, 18 Oct 2018 02:45:32 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Bin Liu <b-liu@...com>
Cc:     Paul Elder <paul.elder@...asonboard.com>,
        kieran.bingham@...asonboard.com, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        balbi@...nel.org, stern@...land.harvard.edu, rogerq@...com
Subject: Re: [PATCH 4/6] usb: gadget: add functions to signal udc driver to delay status stage

Hi Bin,

On Thursday, 11 October 2018 19:10:21 EEST Bin Liu wrote:
> On Tue, Oct 09, 2018 at 10:49:01PM -0400, Paul Elder wrote:
> > A usb gadget function driver may or may not want to delay the status
> > stage of a control OUT request. An instance it might want to is to
> > asynchronously validate the data of a class-specific request.
> > 
> > Add a function usb_ep_delay_status to allow function drivers to choose
> > to delay the status stage in the request completion handler. The UDC
> > should then check the usb_ep->delayed_status flag and act accordingly to
> > delay the status stage.
> > 
> > Also add a function usb_ep_send_response as a wrapper for
> > usb_ep->ops->send_response, whose prototype is added as well. This
> > function should be called by function drivers to tell the UDC what to
> > reply in the status stage that it has requested to be delayed.
> > 
> > Signed-off-by: Paul Elder <paul.elder@...asonboard.com>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > ---
> > 
> >  drivers/usb/gadget/udc/core.c | 35 +++++++++++++++++++++++++++++++++++
> >  include/linux/usb/gadget.h    | 11 +++++++++++
> >  2 files changed, 46 insertions(+)
> > 
> > diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> > index af88b48c1cea..1ec5ce6b43cd 100644
> > --- a/drivers/usb/gadget/udc/core.c
> > +++ b/drivers/usb/gadget/udc/core.c
> > @@ -443,6 +443,41 @@ void usb_ep_fifo_flush(struct usb_ep *ep)
> >  }
> >  EXPORT_SYMBOL_GPL(usb_ep_fifo_flush);
> > 
> > +/**
> > + * usb_ep_ep_delay_status - set delay_status flag
> > + * @ep: the endpoint whose delay_status flag is being set
> > + *
> > + * This function instructs the UDC to delay the status stage of a control
> > + * request. It can only be called from the request completion handler of
> > a
> > + * control request.
> > + */
> > +void usb_ep_delay_status(struct usb_ep *ep)
> > +{
> > +	ep->delayed_status = true;
> > +}
> > +EXPORT_SYMBOL_GPL(usb_ep_delay_status);
> 
> Is usb_ep_set_delay_status() better? I thought it implies get/return
> action if a verb is missing in the function name.

For what it's worth, I understand the function name as "delay the status 
stage", with "delay" being a verb. Maybe the short description could be 
updated accordingly.

-- 
Regards,

Laurent Pinchart