Re: [Qemu-devel] [PATCH 04/12] usb: Add support for input pipelining

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 10/09/2012 03:31 PM, Gerd Hoffmann wrote:

<snip>

>>> The core can and should do that for packets it owns (USBPacketState ==
>>> USB_PACKET_QUEUED) because they are not (yet) passed to the USBDevice.
>>>
>>> Packets owned by USBDevice (USBPacketState == USB_PACKET_ASYNC) must be
>>> handled by the USBDevice itself.
>>
>> Getting offtopic a bit here, but this not how we currently handle
>> things, currently the hcd code cancels packets after a queue halt,
>
> Ah, right.  Well, that should continue to work.  USB_RET_NOT_USED would
> make the hcd code just free the packet, and anything not-yet freed will
> be zapped by the queue halt handling.
>

Right.

<snip>

>> 2) If you agree with 1, then I assume you agree we will want to share
>> the combining code between host-linux.c (or host-* for that matter) and
>> redirect.c ?
>
> I'm not sure there is that much to share.
>

It is not much, but you rightly called it "magic" before, as it is somewhat
tricky code, so better to write (and debug) it once :)

> A helper function which takes a USBEndpoint and returns an iovec for all
> USBPackets lined up there would probably be useful.  Likewise for one
> for completing the packets (takes xfer length + status, then fill
> USBPacket->result & call usb_packet_complete for each packet).

That is more or less what I had in mind yes :)

> But beyond that?
>
>> 3) If you agree with 2, then all we need is a place for the shared logic
>> to live, we could put it in a new file called input-pipeline.c ?
>
> Just stick the helpers into hw/usb/core.c?

I think core.c is getting a bit crowded, so I'll go with a new file for
the next revision, if you don't like that moving the functions someplace
else is easy :)

I'll start working on a new reworked version of the patchset which hopefully
will be more to your liking :)

Regards,

Hans