On Wed, Jan 15, 2014 at 04:52:45PM +0000, Sean Young wrote:
> On Wed, Jan 15, 2014 at 01:49:17PM -0200, Mauro Carvalho Chehab wrote:
> > Hi Martin,
> >
> > Em Wed, 11 Dec 2013 21:34:55 +0100
> > Martin Kittel <linux@xxxxxxxxxxxxxxxx> escreveu:
> >
> > > Hi Mauro, hi Sean,
> > >
> > > thanks for considering the patch. I have added an updated version at the
> > > end of this mail.
> > >
> > > Regarding the info Sean was requesting, it is indeed an xhci hub. I also
> > > added the details of the remote itself.
> > >
> > > Please let me know if there is anything missing.
> > >
> > > Best wishes,
> > >
> > > Martin.
> > >
> > >
> > > lsusb -vvv
> > > ------
> > > Bus 001 Device 002: ID 2304:0225 Pinnacle Systems, Inc. Remote Kit
> > > Infrared Transceiver
> > > Device Descriptor:
> > > bLength 18
> > > bDescriptorType 1
> > > bcdUSB 2.00
> > > bDeviceClass 0 (Defined at Interface level)
> > > bDeviceSubClass 0
> > > bDeviceProtocol 0
> > > bMaxPacketSize0 8
> > > idVendor 0x2304 Pinnacle Systems, Inc.
> > > idProduct 0x0225 Remote Kit Infrared Transceiver
> > > bcdDevice 0.01
> > > iManufacturer 1 Pinnacle Systems
> > > iProduct 2 PCTV Remote USB
> > > iSerial 5 7FFFFFFFFFFFFFFF
> > > bNumConfigurations 1
> > > Configuration Descriptor:
> > > bLength 9
> > > bDescriptorType 2
> > > wTotalLength 32
> > > bNumInterfaces 1
> > > bConfigurationValue 1
> > > iConfiguration 3 StandardConfiguration
> > > bmAttributes 0xa0
> > > (Bus Powered)
> > > Remote Wakeup
> > > MaxPower 100mA
> > > Interface Descriptor:
> > > bLength 9
> > > bDescriptorType 4
> > > bInterfaceNumber 0
> > > bAlternateSetting 0
> > > bNumEndpoints 2
> > > bInterfaceClass 255 Vendor Specific Class
> > > bInterfaceSubClass 0
> > > bInterfaceProtocol 0
> > > iInterface 4 StandardInterface
> > > Endpoint Descriptor:
> > > bLength 7
> > > bDescriptorType 5
> > > bEndpointAddress 0x81 EP 1 IN
> > > bmAttributes 2
> > > Transfer Type Bulk
> > > Synch Type None
> > > Usage Type Data
> > > wMaxPacketSize 0x0040 1x 64 bytes
> > > bInterval 10
> >
> > Hmm... interval is equal to 10, e. g. 125us * 2^(10 - 1) = 64 ms.
> >
> > I'm wandering why mceusb is just forcing the interval to 1 (125ms). That
> > sounds wrong, except, of course, if the endpoint descriptor is wrong.
>
> Note that the endpoint descriptor describes it as a bulk endpoint, but
> it is used as a interrupt endpoint by the driver. For bulk endpoints,
> the interval should not be used (?).
>
> Maybe the correct solution would be to use the endpoints as bulk endpoints
> if that is what the endpoint says? mceusb devices come in interrupt and
> bulk flavours.
Yeah, I just went through a number of my devices here. I have the same
pinnacle one with bulk and 10, a topseed with bulk and 1, a topseed with
interrupt and 0, a philips with bulk and 0... There's a pretty nasty mix
of them. The interrupt and 0 one actually winds up with a default
bInterval of 32 from the usb subsystem, but the bulk/0 one sticks with a
default of 0.
Something to properly handle bulk vs. interrupt might be useful, but at
least at first glance here, simply saying
if (ep_{in,out}->bInterval == 0)
ep_{in,out}->bInterval = 8;
seems to work just fine here with the stack of mceusb devices I've tried
so far (all hooked to usb 1.1 and/or usb 2.0 ports).
> > On my eyes, though, 64ms seems to be a good enough interval to get
> > those events.
>
> Each packet will be 64 bytes, and at 64 ms you should be able to 960
> bytes per second. That's more than enough.
>
> > Jarod/Sean,
> >
> > Are there any good reason for the mceusb driver to do this?
> > ep_in->bInterval = 1;
> > ep_out->bInterval = 1;
>
> I don't know.
It was basically a cover for the bulk/bInterval=0 case.
> The xhci driver is not happy about the interval being changed. With
> CONFIG_USB_DEBUG you get:
>
> usb 3-12: Driver uses different interval (8 microframes) than xHCI (1 microframe)
I suppose I need to get a machine with usb3 up and running to poke at...
--
Jarod Wilson
jarod@xxxxxxxxxx
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