From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
linux-media@vger.kernel.org,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-usb@vger.kernel.org, tglx@linutronix.de,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: USB: note that usb_fill_int_urb() can be used used for ISOC urbs.
Date: Wed, 20 Jun 2018 18:02:00 +0200 [thread overview]
Message-ID: <20180620160200.vxdq4o2azkftpfqs@linutronix.de> (raw)
On 2018-06-20 11:35:05 [-0400], Alan Stern wrote:
> > diff --git a/include/linux/usb.h b/include/linux/usb.h
> > index 4cdd515a4385..c3a8bd586121 100644
> > --- a/include/linux/usb.h
> > +++ b/include/linux/usb.h
> > @@ -1657,7 +1657,8 @@ static inline void usb_fill_bulk_urb(struct urb *urb,
> > * the endpoint descriptor's bInterval value.
> > *
> > * Initializes a interrupt urb with the proper information needed to submit
> > - * it to a device.
> > + * it to a device. This function can also be used to initialize an isochronous
> > + * urb.
>
> No, no! This function can _help_ initialize an isochronous URB, but
> that's all. It would be better to create an explicit
> usb_fill_isoc_urb() routine, and even that would have to be incomplete.
Yes, incomplete. I read incomplete as some additional fields have to be
set which are not set yet. But for FS you write…
> There are two problems with using usb_fill_int_urb() to initialize an
> isochronous URB:
>
> The calculation of the interval value is wrong for full-speed
> devices.
Why wrong?
> The routine does not set urb->number_of_packets or
> urb->iso_frame_desc[].
Yes.
> Alan Stern
Sebastian
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next reply other threads:[~2018-06-20 16:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-20 16:02 Sebastian Andrzej Siewior [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-06-20 17:23 USB: note that usb_fill_int_urb() can be used used for ISOC urbs Alan Stern
2018-06-20 16:49 Sebastian Andrzej Siewior
2018-06-20 16:21 Alan Stern
2018-06-20 15:35 Alan Stern
2018-06-20 15:20 Sebastian Andrzej Siewior
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