On Tue, Feb 27, 2007 at 01:28:12AM -0800, David Brownell wrote:
> On Monday 26 February 2007 9:51 am, Andrea Arcangeli wrote:
> > On Mon, Feb 26, 2007 at 09:36:55AM -0800, David Brownell wrote:
> > > That's not a heuristic ... as I assume you know. No guesswork
> >
> > You assume wrong, I know nothing about that code, ...
>
> I was referring to the definition of a "heuristic". Quoting Wikipedia,
> the relevant part:
>
> Heuristics are intended to gain computational performance or
> conceptual simplicity, potentially at the cost of accuracy
> or precision.
>
> (Or more classically, trading off correctness in some cases to
> achive simplicity ... mostly when a correct algorithm would be
> a real PITA to implement; or is too slow; or hasn't been defined.)
>
> The relevant code is straightforward, and implements exactly the
> "max 90% bandwidth available for periodic transfers" requirement.
> Really simple stuff; no need to trade off aginst correctness.
> Ergo: "not a heuristic".
I know what an heuristic is, and IMHO pretty resembling intelligence
is an heuristic because you cannot proof that a more correct algorithm
cannot exist, which is mostly impossible in 99% of cases.
This 90% number may very well be an heuristic that was written in the
specs (in such case an heuristic not created by linux folks, but still
an heuristic).
> Sounds then like the open() is being weird. Nothing issued a read
> yet; nothing yet said how much bandwidth a read should consume. So
> it has no business submitting an URB (and thus causing ENOSPC).
Ok, so at least this can be improved.
> It may be that a case could be made that the error is in the relevant
> video driver...
It's drivers/media/video/ov511.c if you want to have a look.
> An "lsusb -v" of the devices on that bus, before you open, should help
> sort the details, also the relevant /sys/class/usb_host/usbN/periodic
> file (you may need to configure USB_DEBUG). You'll surely observe
> that everything behaves as long as you don't overcommit the bandwidth.
> And that the ENOSPC error is reported only if you try to overcommit.
Yes, everything is fine if I don't open too many devices at the same time.
Bus 001 Device 005: ID 05a9:a511 OmniVision Technologies, Inc. OV511+ WebCam
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x05a9 OmniVision Technologies, Inc.
idProduct 0xa511 OV511+ WebCam
bcdDevice 1.00
iManufacturer 0
iProduct 0
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 137
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0000 1x 0 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0021 1x 33 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0081 1x 129 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 3
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0101 1x 257 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 4
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0181 1x 385 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 5
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0201 1x 513 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 6
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0301 1x 769 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 7
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x03c1 1x 961 bytes
bInterval 1
Bus 001 Device 004: ID 051d:0002 American Power Conversion Back-UPS Pro
500/1000/1500
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x051d American Power Conversion
idProduct 0x0002 Back-UPS Pro 500/1000/1500
bcdDevice 0.06
iManufacturer 3 American Power Conversion
iProduct 1 Back-UPS CS 650 FW:817.v2.I USB FW:v2
iSerial 2 QB0435143299
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 34
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Devices
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.10
bCountryCode 33 US
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 1216
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0006 1x 6 bytes
bInterval 100
Bus 001 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x067b Prolific Technology, Inc.
idProduct 0x2303 PL2303 Serial Port
bcdDevice 4.00
iManufacturer 1 Prolific Technology Inc.
iProduct 2 USB-Serial Controller D
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 39
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
Remote Wakeup
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x000a 1x 10 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Bus 001 Device 006: ID 15c2:ffdc SoundGraph Inc. iMON PAD Remote Controller
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x15c2 SoundGraph Inc.
idProduct 0xffdc iMON PAD Remote Controller
bcdDevice 0.00
iManufacturer 0
iProduct 0
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 41
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 0 (Defined at Interface level)
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 10
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 10
Bus 001 Device 003: ID 2001:5100 D-Link Corp. [hex]
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.00
bDeviceClass 255 Vendor Specific Class
bDeviceSubClass 255 Vendor Specific Subclass
bDeviceProtocol 255 Vendor Specific Protocol
bMaxPacketSize0 64
idVendor 0x2001 D-Link Corp. [hex]
idProduct 0x5100
bcdDevice 1.00
iManufacturer 1 GlobeSpan Inc.
iProduct 2 USB-ADSL Modem
iSerial 3 UADSLG
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 219
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 1
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x03f0 1x 1008 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 2
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0390 1x 912 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 3
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x02e0 1x 736 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 4
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x01c0 1x 448 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 5
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x00f0 1x 240 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 6
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0050 1x 80 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 3
Bus 001 Device 001: ID 0000:0000
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 9 Hub
bDeviceSubClass 0 Unused
bDeviceProtocol 0 Full speed (or root) hub
bMaxPacketSize0 64
idVendor 0x0000
idProduct 0x0000
bcdDevice 2.06
iManufacturer 3 Linux 2.6.19 ohci_hcd
iProduct 2 OHCI Host Controller
iSerial 1 0000:00:0b.0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 25
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 9 Hub
bInterfaceSubClass 0 Unused
bInterfaceProtocol 0 Full speed (or root) hub
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0002 1x 2 bytes
bInterval 255
Hub Descriptor:
bLength 11
bDescriptorType 41
nNbrPorts 8
wHubCharacteristic 0x0002
No power switching (usb 1.0)
Ganged overcurrent protection
bPwrOn2PwrGood 1 * 2 milli seconds
bHubContrCurrent 0 milli Ampere
DeviceRemovable 0x00 0x02
PortPwrCtrlMask 0x7c 0x06
Hub Port Status:
Port 1: 0000.0103 power enable connect
Port 2: 0000.0100 power
Port 3: 0000.0103 power enable connect
Port 4: 0000.0303 lowspeed power enable connect
Port 5: 0000.0103 power enable connect
Port 6: 0000.0100 power
Port 7: 0000.0303 lowspeed power enable connect
Port 8: 0000.0100 power
Bus 002 Device 001: ID 0000:0000
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 9 Hub
bDeviceSubClass 0 Unused
bDeviceProtocol 1 Single TT
bMaxPacketSize0 64
idVendor 0x0000
idProduct 0x0000
bcdDevice 2.06
iManufacturer 3 Linux 2.6.19 ehci_hcd
iProduct 2 EHCI Host Controller
iSerial 1 0000:00:0b.1
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 25
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 9 Hub
bInterfaceSubClass 0 Unused
bInterfaceProtocol 0 Full speed (or root) hub
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0002 1x 2 bytes
bInterval 12
Hub Descriptor:
bLength 11
bDescriptorType 41
nNbrPorts 8
wHubCharacteristic 0x000a
No power switching (usb 1.0)
Per-port overcurrent protection
TT think time 8 FS bits
bPwrOn2PwrGood 10 * 2 milli seconds
bHubContrCurrent 0 milli Ampere
DeviceRemovable 0x00 0x02
PortPwrCtrlMask 0x7c 0x06
Hub Port Status:
Port 1: 0000.0000
Port 2: 0000.0100 power
Port 3: 0000.0000
Port 4: 0000.0000
Port 5: 0000.0000
Port 6: 0000.0100 power
Port 7: 0000.0000
Port 8: 0000.0100 power
There's the printer connected too but it's off most of the time.
> > And would you then please explain why the bug goes away with my patch? ;)
>
> You're replacing one bug ("operator error") by adding a kernel bug
> (overcommit of periodic bandwidth). I'm quite certain you've seen
> cases where one bug papers over another. This would be a case of
> wanting to introduce a bug to achieve that papering-over...
Sure I understand. However I perhaps wrongly assumed that the worst
side effect of overcommit of periodic bandwidth would be graceful usb
errors at runtime. For an end user, having eciadsl-start sort of
hanging because of that code, or because the usb chokes at runtime
isn't very different I assure. A warning in the logs saying
"bandiwidth exceeded" at runtime and disconnecting the relevant device
at runtime, would be my preferred approach. I think this is what the
old USB_BANDWIDTH=n did, but I may be mistaken since I don't know much
about usb. This approach better assure that we can use the hardware to
the maximum of its capabilities. Now if you tell me that what I'm
doing is plain overclocking (even if the camera at 320x240 and 5
frames per second works perfectly along with the modem), then I can
maintain the patch myself (or I would appreciate an overcommit
sysctl). while searching how to solve the enospc I found more reports
of people that had my same troubles with ENOSPC, and perhaps those
people could also appreciate to try the overcommit sysctl (at their
risk of course! ;).
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