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xHCI bandwidth error with USB webcam

PATCH Sarah Sharp 4 participants 6 messages Apr 12, 2010 – Apr 20, 2010 Media (V4L/DVB)

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Sarah Sharp

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I've been trying out the patches to enable isochronous transfers under xHCI, and they work fine on my USB speaker. However, I've been having trouble getting my high speed USB webcam to work. The NEC Express Card I have rejects the first alternate setting that the uvcvideo driver tries to install (altsetting 11), saying that it takes too much bandwidth. This happens even when I plug the device directly into the roothub with no other devices plugged in.

I would like to know if this is correct behavior for the host, as I can't believe a device would advertise an alternate setting that took up too much bandwidth by itself. Device descriptors and a log snippet are attached.

The other problem is that uvcvideo then gives up on the device when installing the alt setting fails, rather than trying the next less resource-intensive alternate setting. The past, submit_urb() might fail if there wasn't enough bandwidth for the isochronous transfers, but under an xHCI host controller, it will fail sooner, when usb_set_interface() is called. That needs to be fixed in all the USB video drivers.

I figured out how to patch the gspca driver, but not uvcvideo. The patch looks a bit hackish; can with experience with that driver look it over? Can anyone tell me where to look for the usb_set_interface() in uvcvideo?

Sarah Sharp

8<----------------------

Quoted 1 line

From 0e6bc81b178364ee9771c64a06ab006588c73ae6 Mon Sep 17 00:00:00 2001

From: Sarah Sharp <[email protected]>
Date: Mon, 12 Apr 2010 11:23:46 -0700

Subject: [PATCH] gspca: Try a less bandwidth-intensive alt setting.

Under OHCI, UHCI, and EHCI, if an alternate interface setting took too much of the bus bandwidth, then submit_urb() would fail. The xHCI host controller does bandwidth checking when the alternate interface setting is installed, so usb_set_interface() can fail. If it does, try the next alternate interface setting.

Signed-off-by Sarah Sharp <[email protected]>
---
 drivers/media/video/gspca/gspca.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
drivers/media/video/gspca/gspca.c +6 -4
index 222af47..6de3117 100644
@@ -643,6 +643,7 @@ static struct usb_host_endpoint *get_ep(struct gspca_dev *gspca_dev)
 	xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK
 				   : USB_ENDPOINT_XFER_ISOC;
 	i = gspca_dev->alt;			/* previous alt setting */
+find_alt:
 	if (gspca_dev->cam.reverse_alts) {
 		while (++i < gspca_dev->nbalt) {
 			ep = alt_xfer(&intf->altsetting[i], xfer);

@@ -666,10 +667,11 @@ static struct usb_host_endpoint *get_ep(struct gspca_dev *gspca_dev)
 	if (gspca_dev->nbalt > 1) {
 		gspca_input_destroy_urb(gspca_dev);
 		ret = usb_set_interface(gspca_dev->dev, gspca_dev->iface, i);
-		if (ret < 0) {
-			err("set alt %d err %d", i, ret);
-			ep = NULL;
-		}
+		/* xHCI hosts will reject set interface requests
+		 * if they take too much bandwidth, so try again.
+		 */
+		if (ret < 0)
+			goto find_alt;
 		gspca_input_create_urb(gspca_dev);
 	}
 	return ep;
Signature · 1 line
1.6.3.3

Bus 009 Device 002: ID 046d:09a5 Logitech, Inc.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x046d Logitech, Inc.
idProduct 0x09a5
bcdDevice 0.06

  iManufacturer           0 
  iProduct                0 
  iSerial                 2 0A539160
  bNumConfigurations      1

Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 1183
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 0
iInterface 0
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 133
dwClockFrequency 48.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 0
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 3
bmControls 0x0000000e
Auto-Exposure Mode
Auto-Exposure Priority
Exposure Time (Absolute)
VideoControl Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
Warning: Descriptor too short
bUnitID 2
bSourceID 1
wMaxMultiplier 16384
bControlSize 2
bmControls 0x0000175b
Brightness
Contrast
Saturation
Sharpness
White Balance Temperature
Backlight Compensation
Gain
Power Line Frequency
White Balance Temperature, Auto
iProcessing 0
bmVideoStandards 0x1b
None
NTSC - 525/60
SECAM - 625/50
NTSC - 625/50
VideoControl Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 4
guidExtensionCode {82066163-7050-ab49-b8cc-b3855e8d221e}
bNumControl 10
bNrPins 1
baSourceID( 0) 2
bControlSize 2
bmControls( 0) 0xff
bmControls( 1) 0x03
iExtension 0
VideoControl Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 13
guidExtensionCode {82066163-7050-ab49-b8cc-b3855e8d221f}
bNumControl 8
bNrPins 1
baSourceID( 0) 2
bControlSize 2
bmControls( 0) 0x7f
bmControls( 1) 0x01
iExtension 0
VideoControl Interface Descriptor:
bLength 28
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 10
guidExtensionCode {82066163-7050-ab49-b8cc-b3855e8d2252}
bNumControl 24
bNrPins 1
baSourceID( 0) 4
bControlSize 3
bmControls( 0) 0xff
bmControls( 1) 0xff
bmControls( 2) 0xff
iExtension 0
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 5
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 4
iTerminal 0
** UNRECOGNIZED: 20 41 01 0c 82 06 61 63 70 50 ab 49 b8 cc b3 85 5e 8d 22 50 14 01 04 03 ff ff 0f 00 00 00 00 00 ** UNRECOGNIZED: 20 41 01 08 82 06 61 63 70 50 ab 49 b8 cc b3 85 5e 8d 22 51 03 01 04 03 19 00 00 00 00 00 01 00 ** UNRECOGNIZED: 20 41 01 0b 82 06 61 63 70 50 ab 49 b8 cc b3 85 5e 8d 22 55 01 01 04 03 01 00 00 00 00 00 00 00 Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x87 EP 7 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0010 1x 16 bytes
bInterval 8
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
VideoStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 3
wTotalLength 624
bEndPointAddress 129
bmInfo 0
bTerminalLink 5
bStillCaptureMethod 2
bTriggerSupport 1
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 11
bmaControls( 1) 11
bmaControls( 2) 11
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 5
bFlags 1
Fixed-size samples: Yes
bDefaultFrameIndex 3
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 160
wHeight 120
dwMinBitRate 1536000
dwMaxBitRate 9216000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 176
wHeight 144
dwMinBitRate 2027520
dwMaxBitRate 12165120
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 6144000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 8110080
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 24576000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 31
bDescriptorType 36
bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
bEndpointAddress 0
bNumImageSizePatterns 5
wWidth( 0) 160
wHeight( 0) 120
wWidth( 1) 176
wHeight( 1) 144
wWidth( 2) 320
wHeight( 2) 240
wWidth( 3) 352
wHeight( 3) 288
wWidth( 4) 640
wHeight( 4) 480
bNumCompressionPatterns 5
bCompression( 0) 5
bCompression( 1) 10
bCompression( 2) 15
bCompression( 3) 20
bCompression( 4) 25
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 2
bNumFrameDescriptors 5
guidFormat {59555932-0000-1000-8000-00aa00389b71}
bBitsPerPixel 16
bDefaultFrameIndex 3
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 160
wHeight 120
dwMinBitRate 1536000
dwMaxBitRate 9216000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 176
wHeight 144
dwMinBitRate 2027520
dwMaxBitRate 12165120
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 6144000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 8110080
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 24576000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 666666
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
bEndpointAddress 0
bNumImageSizePatterns 5
wWidth( 0) 160
wHeight( 0) 120
wWidth( 1) 176
wHeight( 1) 144
wWidth( 2) 320
wHeight( 2) 240
wWidth( 3) 352
wHeight( 3) 288
wWidth( 4) 640
wHeight( 4) 480
bNumCompressionPatterns 5
bCompression( 0) 5
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0180 1x 384 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 3
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 4
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0280 1x 640 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 5
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0320 1x 800 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 6
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x03b0 1x 944 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 7
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0a80 2x 640 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 8
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0b20 2x 800 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 9
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0be0 2x 992 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 10
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x1380 3x 896 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 11
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x13fc 3x 1020 bytes
bInterval 1
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 2
bInterfaceCount 2
bFunctionClass 1 Audio
bFunctionSubClass 2 Streaming
bFunctionProtocol 0
iFunction 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 38
bInCollection 1
baInterfaceNr( 0) 3
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bNrChannels 1
wChannelConfig 0x0000
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 1
bSourceID 5
iTerminal 0
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 5
bSourceID 1
bControlSize 1
bmaControls( 0) 0x03
Mute
Volume
iFeature 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 3
bDelay 1 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 16000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x86 EP 6 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0024 1x 36 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0000
(Bus Powered)

Apr  9 16:20:55 xanatos kernel: [ 1425.109695] usb 9-3.2: ep 0x81 - rounding interval to 1 microframes
Apr  9 16:20:55 xanatos kernel: [ 1425.109699] xhci_hcd 0000:05:00.0: add ep 0x81, slot id 3, new drop flags = 0x0, new add flags = 0x8, new slot info = 0x18300002
Apr  9 16:20:55 xanatos kernel: [ 1425.109703] xhci_hcd 0000:05:00.0: xhci_check_bandwidth called for udev ffff880070557000
Apr  9 16:20:55 xanatos kernel: [ 1425.109705] xhci_hcd 0000:05:00.0: New Input Control Context:
Apr  9 16:20:55 xanatos kernel: [ 1425.109709] xhci_hcd 0000:05:00.0: @ffff88006cb9b000 (virt) @6cb9b000 (dma) 0x000000 - drop flags
Apr  9 16:20:55 xanatos kernel: [ 1425.109712] xhci_hcd 0000:05:00.0: @ffff88006cb9b004 (virt) @6cb9b004 (dma) 0x000009 - add flags
Apr  9 16:20:55 xanatos kernel: [ 1425.109716] xhci_hcd 0000:05:00.0: @ffff88006cb9b008 (virt) @6cb9b008 (dma) 0x000000 - rsvd2[0]
Apr  9 16:20:55 xanatos kernel: [ 1425.109719] xhci_hcd 0000:05:00.0: @ffff88006cb9b00c (virt) @6cb9b00c (dma) 0x000000 - rsvd2[1]
Apr  9 16:20:55 xanatos kernel: [ 1425.109723] xhci_hcd 0000:05:00.0: @ffff88006cb9b010 (virt) @6cb9b010 (dma) 0x000000 - rsvd2[2]
Apr  9 16:20:55 xanatos kernel: [ 1425.109726] xhci_hcd 0000:05:00.0: @ffff88006cb9b014 (virt) @6cb9b014 (dma) 0x000000 - rsvd2[3]
Apr  9 16:20:55 xanatos kernel: [ 1425.109730] xhci_hcd 0000:05:00.0: @ffff88006cb9b018 (virt) @6cb9b018 (dma) 0x000000 - rsvd2[4]
Apr  9 16:20:55 xanatos kernel: [ 1425.109733] xhci_hcd 0000:05:00.0: @ffff88006cb9b01c (virt) @6cb9b01c (dma) 0x000000 - rsvd2[5]
Apr  9 16:20:55 xanatos kernel: [ 1425.109736] xhci_hcd 0000:05:00.0: Slot Context:
Apr  9 16:20:55 xanatos kernel: [ 1425.109739] xhci_hcd 0000:05:00.0: @ffff88006cb9b020 (virt) @6cb9b020 (dma) 0x18300002 - dev_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109742] xhci_hcd 0000:05:00.0: @ffff88006cb9b024 (virt) @6cb9b024 (dma) 0x030000 - dev_info2
Apr  9 16:20:55 xanatos kernel: [ 1425.109746] xhci_hcd 0000:05:00.0: @ffff88006cb9b028 (virt) @6cb9b028 (dma) 0x000000 - tt_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109749] xhci_hcd 0000:05:00.0: @ffff88006cb9b02c (virt) @6cb9b02c (dma) 0x000000 - dev_state
Apr  9 16:20:55 xanatos kernel: [ 1425.109753] xhci_hcd 0000:05:00.0: @ffff88006cb9b030 (virt) @6cb9b030 (dma) 0x000000 - rsvd[0]
Apr  9 16:20:55 xanatos kernel: [ 1425.109756] xhci_hcd 0000:05:00.0: @ffff88006cb9b034 (virt) @6cb9b034 (dma) 0x000000 - rsvd[1]
Apr  9 16:20:55 xanatos kernel: [ 1425.109759] xhci_hcd 0000:05:00.0: @ffff88006cb9b038 (virt) @6cb9b038 (dma) 0x000000 - rsvd[2]
Apr  9 16:20:55 xanatos kernel: [ 1425.109763] xhci_hcd 0000:05:00.0: @ffff88006cb9b03c (virt) @6cb9b03c (dma) 0x000000 - rsvd[3]
Apr  9 16:20:55 xanatos kernel: [ 1425.109766] xhci_hcd 0000:05:00.0: Endpoint 00 Context:
Apr  9 16:20:55 xanatos kernel: [ 1425.109768] xhci_hcd 0000:05:00.0: @ffff88006cb9b040 (virt) @6cb9b040 (dma) 0x000000 - ep_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109772] xhci_hcd 0000:05:00.0: @ffff88006cb9b044 (virt) @6cb9b044 (dma) 0x400026 - ep_info2
Apr  9 16:20:55 xanatos kernel: [ 1425.109775] xhci_hcd 0000:05:00.0: @ffff88006cb9b048 (virt) @6cb9b048 (dma) 0x578e6001 - deq
Apr  9 16:20:55 xanatos kernel: [ 1425.109778] xhci_hcd 0000:05:00.0: @ffff88006cb9b050 (virt) @6cb9b050 (dma) 0x000000 - tx_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109782] xhci_hcd 0000:05:00.0: @ffff88006cb9b054 (virt) @6cb9b054 (dma) 0x000000 - rsvd[0]
Apr  9 16:20:55 xanatos kernel: [ 1425.109785] xhci_hcd 0000:05:00.0: @ffff88006cb9b058 (virt) @6cb9b058 (dma) 0x000000 - rsvd[1]
Apr  9 16:20:55 xanatos kernel: [ 1425.109789] xhci_hcd 0000:05:00.0: @ffff88006cb9b05c (virt) @6cb9b05c (dma) 0x000000 - rsvd[2]
Apr  9 16:20:55 xanatos kernel: [ 1425.109792] xhci_hcd 0000:05:00.0: Endpoint 01 Context:
Apr  9 16:20:55 xanatos kernel: [ 1425.109795] xhci_hcd 0000:05:00.0: @ffff88006cb9b060 (virt) @6cb9b060 (dma) 0x000000 - ep_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109798] xhci_hcd 0000:05:00.0: @ffff88006cb9b064 (virt) @6cb9b064 (dma) 0x000000 - ep_info2
Apr  9 16:20:55 xanatos kernel: [ 1425.109801] xhci_hcd 0000:05:00.0: @ffff88006cb9b068 (virt) @6cb9b068 (dma) 0x000000 - deq
Apr  9 16:20:55 xanatos kernel: [ 1425.109805] xhci_hcd 0000:05:00.0: @ffff88006cb9b070 (virt) @6cb9b070 (dma) 0x000000 - tx_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109808] xhci_hcd 0000:05:00.0: @ffff88006cb9b074 (virt) @6cb9b074 (dma) 0x000000 - rsvd[0]
Apr  9 16:20:55 xanatos kernel: [ 1425.109812] xhci_hcd 0000:05:00.0: @ffff88006cb9b078 (virt) @6cb9b078 (dma) 0x000000 - rsvd[1]
Apr  9 16:20:55 xanatos kernel: [ 1425.109815] xhci_hcd 0000:05:00.0: @ffff88006cb9b07c (virt) @6cb9b07c (dma) 0x000000 - rsvd[2]
Apr  9 16:20:55 xanatos kernel: [ 1425.109818] xhci_hcd 0000:05:00.0: Endpoint 02 Context:
Apr  9 16:20:55 xanatos kernel: [ 1425.109821] xhci_hcd 0000:05:00.0: @ffff88006cb9b080 (virt) @6cb9b080 (dma) 0x000000 - ep_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109824] xhci_hcd 0000:05:00.0: @ffff88006cb9b084 (virt) @6cb9b084 (dma) 0x3fc022a - ep_info2
Apr  9 16:20:55 xanatos kernel: [ 1425.109828] xhci_hcd 0000:05:00.0: @ffff88006cb9b088 (virt) @6cb9b088 (dma) 0x657a8001 - deq
Apr  9 16:20:55 xanatos kernel: [ 1425.109831] xhci_hcd 0000:05:00.0: @ffff88006cb9b090 (virt) @6cb9b090 (dma) 0x000000 - tx_info
Apr  9 16:20:55 xanatos kernel: [ 1425.109834] xhci_hcd 0000:05:00.0: @ffff88006cb9b094 (virt) @6cb9b094 (dma) 0x000000 - rsvd[0]
Apr  9 16:20:55 xanatos kernel: [ 1425.109838] xhci_hcd 0000:05:00.0: @ffff88006cb9b098 (virt) @6cb9b098 (dma) 0x000000 - rsvd[1]
Apr  9 16:20:55 xanatos kernel: [ 1425.109841] xhci_hcd 0000:05:00.0: @ffff88006cb9b09c (virt) @6cb9b09c (dma) 0x000000 - rsvd[2]
Apr  9 16:20:55 xanatos kernel: [ 1425.109845] xhci_hcd 0000:05:00.0: Command ring enq = 0x671d6210 (DMA)
Apr  9 16:20:55 xanatos kernel: [ 1425.109848] xhci_hcd 0000:05:00.0: // Ding dong!
Apr  9 16:20:55 xanatos kernel: [ 1425.109854] xhci_hcd 0000:05:00.0: `MEM_WRITE_DWORD(3'b000, 32'hffffc90019534800, 32'h0, 4'hf);
Apr  9 16:20:55 xanatos kernel: [ 1425.110026] xhci_hcd 0000:05:00.0: op reg status = 00000008
Apr  9 16:20:55 xanatos kernel: [ 1425.110029] xhci_hcd 0000:05:00.0: ir set irq_pending = 00000003
Apr  9 16:20:55 xanatos kernel: [ 1425.110031] xhci_hcd 0000:05:00.0: Event ring dequeue ptr:
Apr  9 16:20:55 xanatos kernel: [ 1425.110034] xhci_hcd 0000:05:00.0: @671d64d0 671d6200 00000000 08000000 03008400
Apr  9 16:20:55 xanatos kernel: [ 1425.110041] xhci_hcd 0000:05:00.0: `MEM_WRITE_DWORD(3'b000, 32'hffffc90019534024, 32'h8, 4'hf);
Apr  9 16:20:55 xanatos kernel: [ 1425.110048] xhci_hcd 0000:05:00.0: `MEM_WRITE_DWORD(3'b000, 32'hffffc90019534620, 32'h3, 4'hf);
Apr  9 16:20:55 xanatos kernel: [ 1425.110055] xhci_hcd 0000:05:00.0: In xhci_handle_event
Apr  9 16:20:55 xanatos kernel: [ 1425.110057] xhci_hcd 0000:05:00.0: xhci_handle_event - OS owns TRB
Apr  9 16:20:55 xanatos kernel: [ 1425.110060] xhci_hcd 0000:05:00.0: xhci_handle_event - calling handle_cmd_completion
Apr  9 16:20:55 xanatos kernel: [ 1425.110063] xhci_hcd 0000:05:00.0: Completed config ep cmd
Apr  9 16:20:55 xanatos kernel: [ 1425.110067] xhci_hcd 0000:05:00.0: Command ring deq = 0x671d6210 (DMA)
Apr  9 16:20:55 xanatos kernel: [ 1425.110070] xhci_hcd 0000:05:00.0: xhci_handle_event - returned from handle_cmd_completion
Apr  9 16:20:55 xanatos kernel: [ 1425.110073] xhci_hcd 0000:05:00.0: Event ring deq = 0x671d64e0 (DMA)
Apr  9 16:20:55 xanatos kernel: [ 1425.110082] xhci_hcd 0000:05:00.0: // Write event ring dequeue pointer, preserving EHB bit
Apr  9 16:20:55 xanatos kernel: [ 1425.110085] xhci_hcd 0000:05:00.0: `MEM_WRITE_DWORD(3'b000, 64'hffffc90019534638, 64'h671d64e0, 4'hf);
Apr  9 16:20:55 xanatos kernel: [ 1425.110088] xhci_hcd 0000:05:00.0: In xhci_handle_event
Apr  9 16:20:55 xanatos kernel: [ 1425.110098] xhci_hcd 0000:05:00.0: `MEM_WRITE_DWORD(3'b000, 64'hffffc90019534638, 64'h671d64e8, 4'hf);
Apr  9 16:20:55 xanatos kernel: [ 1425.110109] usb 9-3.2: Not enough bandwidth for new device state.
Apr  9 16:20:55 xanatos kernel: [ 1425.110112] xhci_hcd 0000:05:00.0: xhci_reset_bandwidth called for udev ffff880070557000
Apr  9 16:20:55 xanatos kernel: [ 1425.110116] xhci_hcd 0000:05:00.0: Freeing ring at ffff88006b866780
Apr  9 16:20:55 xanatos kernel: [ 1425.110119] xhci_hcd 0000:05:00.0: Freeing DMA segment at ffff8800657a8000 (virtual) 0x657a8000 (DMA)
Apr  9 16:20:55 xanatos kernel: [ 1425.110122] xhci_hcd 0000:05:00.0: Freeing priv segment structure at ffff880076c0c040
Apr  9 16:20:55 xanatos kernel: [ 1425.110131] usb 9-3.2: Not enough bandwidth for altsetting 11
#1 lore raw
Quoted 8 lines · Sarah Sharp

I've been trying out the patches to enable isochronous transfers under xHCI, and they work fine on my USB speaker. However, I've been having trouble getting my high speed USB webcam to work. The NEC Express Card I have rejects the first alternate setting that the uvcvideo driver tries to install (altsetting 11), saying that it takes too much bandwidth. This happens even when I plug the device directly into the roothub with no other devices plugged in.

Quoted 4 lines

I would like to know if this is correct behavior for the host, as I can't believe a device would advertise an alternate setting that took up too much bandwidth by itself. Device descriptors and a log snippet are attached.

The webcam is a high-speed device, right? The descriptors call for an isochronous-IN endpoint with 3x1020 bytes (period 1 uframe) and an isochronous-IN endpoint with 36 bytes (period 8 uframes). That combination does not exceed the high-speed bandwidth limit, so the controller should accept it.

Broadly speaking, at 480 Mb/s you get 60 KB/ms = 7500 B/uframe. The periodic bandwidth limit is 80% of the total, or 6000 B/uframe. Taking bitstuffing into account (6/7) leaves 5142 B/uframe available for data, and overhead eats up some of that. It's still much more than the 3*1020 + 36 = 3096 bytes needed by the webcam.

Quoted 8 lines

The other problem is that uvcvideo then gives up on the device when installing the alt setting fails, rather than trying the next less resource-intensive alternate setting. The past, submit_urb() might fail if there wasn't enough bandwidth for the isochronous transfers, but under an xHCI host controller, it will fail sooner, when usb_set_interface() is called. That needs to be fixed in all the USB video drivers.

Quoted 4 lines

I figured out how to patch the gspca driver, but not uvcvideo. The patch looks a bit hackish; can with experience with that driver look it over? Can anyone tell me where to look for the usb_set_interface() in uvcvideo?

Not at the moment, sorry.

Alan Stern

#2 lore raw
In reply to Sarah Sharp

Am Dienstag, 13. April 2010 00:29:32 schrieb Sarah Sharp:

Quoted 4 lines

I figured out how to patch the gspca driver, but not uvcvideo. The patch looks a bit hackish; can with experience with that driver look it over? Can anyone tell me where to look for the usb_set_interface() in uvcvideo?

drivers/media/video/uvc/uvc_video.c::uvc_init_video()

But you'll have no luck there. uvcvideo already selects the altsetting with the lowest bandwidth required for a resolution/format.

Regards
Oliver

#3 lore raw
In reply to Sarah Sharp
Quoted 6 lines

-----Original Message-----
From: Sarah Sharp [mailto:[email protected]]

I've been trying out the patches to enable isochronous transfers under xHCI, and they work fine on my USB speaker. However, I've been having trouble getting my high speed USB webcam to work. The NEC Express

Card

Quoted 7 lines

I have rejects the first alternate setting that the uvcvideo driver tries to install (altsetting 11), saying that it takes too much bandwidth. This happens even when I plug the device directly into the roothub with no other devices plugged in.

I would like to know if this is correct behavior for the host, as I can't believe a device would advertise an alternate setting that took

up

Quoted 1 line

too much bandwidth by itself. Device descriptors and a log snippet

are

Quoted 1 line

attached.

I'm also verifying usb webcam these days. The host controller also rejects alternate setting, indicating not enough bandwidth. Fortunately the webcam I used is using gspca and the patch for gspca below does work. After several times of failure, it will set the alt setting successfully. See the log and descriptors.

But I don't think it's normal behavior. The xHC should accept the alt setting request at the first time. I'm also using the NEC chips, perhaps it's a HW or FW issue but I can't make sure.

Another problem of the isoc transfer is the size of the transfer ring. Currently in xhci_endpoint_init() of xhci-mem.c, the ring allocated for each endpoint just contains one segment, which can hold 64 - 1 = 63 trbs. But the gspca will submit 3 urbs at one time, each consists of 32 packets. Each packet needs an isoc TD to carry, and the driver will insert 96 trbs to the ring at one time. It will cause the room_on_ring check failure since the xHC cannot process the trbs in time. After I modify the parameter of xhci_ring_alloc() in xhci_endpoint_init() to allocate 2 segments, the webcam works smoothly. It looks like dynamic ring allocation is necessary for isoc endpoint since it will put multiple trbs on the ring and the fixed size is too small.

Quoted 3 lines

The other problem is that uvcvideo then gives up on the device when installing the alt setting fails, rather than trying the next less resource-intensive alternate setting. The past, submit_urb() might

fail

Quoted 7 lines

if there wasn't enough bandwidth for the isochronous transfers, but under an xHCI host controller, it will fail sooner, when usb_set_interface() is called. That needs to be fixed in all the USB video drivers.

I figured out how to patch the gspca driver, but not uvcvideo. The patch looks a bit hackish; can with experience with that driver look

it

Quoted 7 lines

over? Can anyone tell me where to look for the usb_set_interface() in uvcvideo?

Sarah Sharp

8<----------------------

Quoted 8 lines

From 0e6bc81b178364ee9771c64a06ab006588c73ae6 Mon Sep 17 00:00:00 2001
From: Sarah Sharp <[email protected]>
Date: Mon, 12 Apr 2010 11:23:46 -0700

Subject: [PATCH] gspca: Try a less bandwidth-intensive alt setting.

Under OHCI, UHCI, and EHCI, if an alternate interface setting took too much of the bus bandwidth, then submit_urb() would fail. The xHCI

host

Quoted 1 line

controller does bandwidth checking when the alternate interface

setting is

Quoted 14 lines

installed, so usb_set_interface() can fail. If it does, try the next alternate interface setting.

Signed-off-by Sarah Sharp <[email protected]>
---
 drivers/media/video/gspca/gspca.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
drivers/media/video/gspca/gspca.c +0 -0
index 222af47..6de3117 100644

drivers/media/video/gspca/gspca.c static struct usb_host_endpoint *get_ep(struct · line 646

Quoted 4 lines
drivers/media/video/gspca/gspca.c +0 -0
@@ -643,6 +643,7 @@ static struct usb_host_endpoint *get_ep(struct
 gspca_dev *gspca_dev)
 	xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK
 				   : USB_ENDPOINT_XFER_ISOC;
 	i = gspca_dev->alt;			/* previous alt setting

*/

drivers/media/video/gspca/gspca.c static struct usb_host_endpoint *get_ep(struct · line 670

Quoted 9 lines
drivers/media/video/gspca/gspca.c +1 -0
+find_alt:
 	if (gspca_dev->cam.reverse_alts) {
 		while (++i < gspca_dev->nbalt) {
drivers/media/video/gspca/gspca.c +0 -0
 			ep = alt_xfer(&intf->altsetting[i], xfer);

@@ -666,10 +667,11 @@ static struct usb_host_endpoint *get_ep(struct
 gspca_dev *gspca_dev)
 	if (gspca_dev->nbalt > 1) {
 		gspca_input_destroy_urb(gspca_dev);
 		ret = usb_set_interface(gspca_dev->dev,

gspca_dev->iface, i);

Quoted 11 lines
drivers/media/video/gspca/gspca.c +5 -4
-		if (ret < 0) {
-			err("set alt %d err %d", i, ret);
-			ep = NULL;
-		}
+		/* xHCI hosts will reject set interface requests
+		 * if they take too much bandwidth, so try again.
+		 */
+		if (ret < 0)
+			goto find_alt;
 		gspca_input_create_urb(gspca_dev);
 	}
Quoted 3 lines

return ep;
--
1.6.3.3

Bus 008 Device 002: ID 04fc:0561 Sunplus Technology Co., Ltd Flexcam 100 Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 255 Vendor Specific Class
bDeviceSubClass 255 Vendor Specific Subclass
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x04fc Sunplus Technology Co., Ltd
idProduct 0x0561 Flexcam 100
bcdDevice 0.00

  iManufacturer           1 Sunplus Technology Co., Ltd.
  iProduct                2 Generic Digital camera
  iSerial                 0 
  bNumConfigurations      1

Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 233
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
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 0x0080 1x 128 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 0x0370 1x 880 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 0x0200 1x 512 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 0x0280 1x 640 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 0x0300 1x 768 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 0x0380 1x 896 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 0x03ff 1x 1023 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 8
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 0x0220 1x 544 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 9
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 0x0290 1x 656 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 10
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 0x02c0 1x 704 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 11
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 0x0360 1x 864 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 12
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 0x03c0 1x 960 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 13
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 0x034d 1x 845 bytes
bInterval 1
Device Status: 0x0000
(Bus Powered)

[  613.660157] xhci_hcd 0000:02:00.0: Can't reset device (slot ID 1) in enabled/disabled state
[  613.660165] xhci_hcd 0000:02:00.0: Not freeing device rings.
[  613.660188] usb 8-4: new full speed USB device using xhci_hcd and address 0
[  613.728243] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.736243] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.746239] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.747450] usb 8-4: configuration #1 chosen from 1 choice
[  613.897124] Linux video capture interface: v2.00
[  613.939447] gspca: main v2.7.0 registered
[  613.961659] gspca: probing 04fc:0561
[  614.429514] gspca: probe ok
[  614.429557] usbcore: registered new interface driver spca561
[  614.430108] spca561: registered
[  617.122122] usb 8-4: Not enough bandwidth for new device state.
[  617.122140] usb 8-4: Not enough bandwidth for altsetting 7
[  617.122146] gspca: set alt 7 err -28
[  617.122378] usb 8-4: Not enough bandwidth for new device state.
[  617.122392] usb 8-4: Not enough bandwidth for altsetting 6
[  617.122397] gspca: set alt 6 err -28
[  619.093780] usb 8-4: Not enough bandwidth for new device state.
[  619.093788] usb 8-4: Not enough bandwidth for altsetting 7
[  619.093791] gspca: set alt 7 err -28
[  619.094016] usb 8-4: Not enough bandwidth for new device state.
[  619.094024] usb 8-4: Not enough bandwidth for altsetting 6
[  619.094026] gspca: set alt 6 err -28
author
#4 lore raw
Quoted 16 lines · Andiry
Quoted 6 lines

-----Original Message-----
From: Sarah Sharp [mailto:[email protected]]

I've been trying out the patches to enable isochronous transfers under xHCI, and they work fine on my USB speaker. However, I've been having trouble getting my high speed USB webcam to work. The NEC Express

Card

Quoted 7 lines

I have rejects the first alternate setting that the uvcvideo driver tries to install (altsetting 11), saying that it takes too much bandwidth. This happens even when I plug the device directly into the roothub with no other devices plugged in.

I would like to know if this is correct behavior for the host, as I can't believe a device would advertise an alternate setting that took

up

Quoted 1 line

too much bandwidth by itself. Device descriptors and a log snippet

Quoted 8 lines

are

Quoted 1 line

attached.

I'm also verifying usb webcam these days. The host controller also rejects alternate setting, indicating not enough bandwidth. Fortunately the webcam I used is using gspca and the patch for gspca below does work. After several times of failure, it will set the alt setting successfully. See the log and descriptors.

Good to know that works! I'll resubmit it as a real patch then.

Quoted 3 lines

But I don't think it's normal behavior. The xHC should accept the alt setting request at the first time. I'm also using the NEC chips, perhaps it's a HW or FW issue but I can't make sure.

I have a patch to fix this. I wasn't setting the Average TRB Length or Max ESIT fields in the isoc endpoint descriptor. Apparently the NEC chip only needs the avg. TRB length to accept the alternate setting, but the xHCI spec says it's really the max ESIT payload that is used for scheduling, so I've set both.

I'll send the patch in a view minutes. Unfortunately, with my gspca full speed webcam, I hang my machine after installing the interface, when the driver first submits an isochronous URB. It's a "scheduling while atomic" error with a very odd backtrace. But it happens every time I plug in the webcam, so I know it's related to that. Gzipped log file is attached. Ignore the values of the tx_info field in the endpoint, I had a bug with the math in the patch that I've since fixed.

Quoted 4 lines

Another problem of the isoc transfer is the size of the transfer ring. Currently in xhci_endpoint_init() of xhci-mem.c, the ring allocated for each endpoint just contains one segment, which can hold 64 - 1 = 63 trbs. But the gspca will submit 3 urbs at one time, each consists

Quoted 8 lines

of 32 packets. Each packet needs an isoc TD to carry, and the driver will insert 96 trbs to the ring at one time. It will cause the room_on_ring check failure since the xHC cannot process the trbs in time. After I modify the parameter of xhci_ring_alloc() in xhci_endpoint_init() to allocate 2 segments, the webcam works smoothly. It looks like dynamic ring allocation is necessary for isoc endpoint since it will put multiple trbs on the ring and the fixed size is too small.

Yes, it looks like dynamic ring resizing is necessary, but feel free to submit your patch for xhci_endpoint_init() for now.

Sarah Sharp

Quoted 394 lines
Quoted 10 lines

8<----------------------

From 0e6bc81b178364ee9771c64a06ab006588c73ae6 Mon Sep 17 00:00:00 2001
From: Sarah Sharp <[email protected]>
Date: Mon, 12 Apr 2010 11:23:46 -0700

Subject: [PATCH] gspca: Try a less bandwidth-intensive alt setting.

Under OHCI, UHCI, and EHCI, if an alternate interface setting took too much of the bus bandwidth, then submit_urb() would fail. The xHCI

host

Quoted 1 line

controller does bandwidth checking when the alternate interface

setting is

Quoted 14 lines

installed, so usb_set_interface() can fail. If it does, try the next alternate interface setting.

Signed-off-by Sarah Sharp <[email protected]>
---
 drivers/media/video/gspca/gspca.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
drivers/media/video/gspca/gspca.c +0 -0
index 222af47..6de3117 100644

drivers/media/video/gspca/gspca.c static struct usb_host_endpoint *get_ep(struct · line 646

Quoted 4 lines
drivers/media/video/gspca/gspca.c +0 -0
@@ -643,6 +643,7 @@ static struct usb_host_endpoint *get_ep(struct
 gspca_dev *gspca_dev)
 	xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK
 				   : USB_ENDPOINT_XFER_ISOC;
 	i = gspca_dev->alt;			/* previous alt setting

*/

drivers/media/video/gspca/gspca.c static struct usb_host_endpoint *get_ep(struct · line 670

Quoted 9 lines
drivers/media/video/gspca/gspca.c +1 -0
+find_alt:
 	if (gspca_dev->cam.reverse_alts) {
 		while (++i < gspca_dev->nbalt) {
drivers/media/video/gspca/gspca.c +0 -0
 			ep = alt_xfer(&intf->altsetting[i], xfer);

@@ -666,10 +667,11 @@ static struct usb_host_endpoint *get_ep(struct
 gspca_dev *gspca_dev)
 	if (gspca_dev->nbalt > 1) {
 		gspca_input_destroy_urb(gspca_dev);
 		ret = usb_set_interface(gspca_dev->dev,

gspca_dev->iface, i);

Quoted 11 lines
drivers/media/video/gspca/gspca.c +5 -4
-		if (ret < 0) {
-			err("set alt %d err %d", i, ret);
-			ep = NULL;
-		}
+		/* xHCI hosts will reject set interface requests
+		 * if they take too much bandwidth, so try again.
+		 */
+		if (ret < 0)
+			goto find_alt;
 		gspca_input_create_urb(gspca_dev);
 	}
Quoted 3 lines

return ep;
--
1.6.3.3

Bus 008 Device 002: ID 04fc:0561 Sunplus Technology Co., Ltd Flexcam 100 Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 255 Vendor Specific Class
bDeviceSubClass 255 Vendor Specific Subclass
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x04fc Sunplus Technology Co., Ltd
idProduct 0x0561 Flexcam 100
bcdDevice 0.00

  iManufacturer           1 Sunplus Technology Co., Ltd.
  iProduct                2 Generic Digital camera
  iSerial                 0 
  bNumConfigurations      1

Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 233
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
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 0x0080 1x 128 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 0x0370 1x 880 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 0x0200 1x 512 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 0x0280 1x 640 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 0x0300 1x 768 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 0x0380 1x 896 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 0x03ff 1x 1023 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 8
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 0x0220 1x 544 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 9
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 0x0290 1x 656 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 10
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 0x02c0 1x 704 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 11
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 0x0360 1x 864 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 12
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 0x03c0 1x 960 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 13
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 0x034d 1x 845 bytes
bInterval 1
Device Status: 0x0000
(Bus Powered)

[  613.660157] xhci_hcd 0000:02:00.0: Can't reset device (slot ID 1) in enabled/disabled state
[  613.660165] xhci_hcd 0000:02:00.0: Not freeing device rings.
[  613.660188] usb 8-4: new full speed USB device using xhci_hcd and address 0
[  613.728243] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.736243] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.746239] xhci_hcd 0000:02:00.0: WARN: short transfer on control ep
[  613.747450] usb 8-4: configuration #1 chosen from 1 choice
[  613.897124] Linux video capture interface: v2.00
[  613.939447] gspca: main v2.7.0 registered
[  613.961659] gspca: probing 04fc:0561
[  614.429514] gspca: probe ok
[  614.429557] usbcore: registered new interface driver spca561
[  614.430108] spca561: registered
[  617.122122] usb 8-4: Not enough bandwidth for new device state.
[  617.122140] usb 8-4: Not enough bandwidth for altsetting 7
[  617.122146] gspca: set alt 7 err -28
[  617.122378] usb 8-4: Not enough bandwidth for new device state.
[  617.122392] usb 8-4: Not enough bandwidth for altsetting 6
[  617.122397] gspca: set alt 6 err -28
[  619.093780] usb 8-4: Not enough bandwidth for new device state.
[  619.093788] usb 8-4: Not enough bandwidth for altsetting 7
[  619.093791] gspca: set alt 7 err -28
[  619.094016] usb 8-4: Not enough bandwidth for new device state.
[  619.094024] usb 8-4: Not enough bandwidth for altsetting 6
[  619.094026] gspca: set alt 6 err -28
#5 lore raw
Quoted 12 lines · Sarah Sharp
Quoted 5 lines

I'm also verifying usb webcam these days. The host controller also rejects alternate setting, indicating not enough bandwidth. Fortunately the webcam I used is using gspca and the patch for gspca below does work. After several times of failure, it will set the alt setting successfully. See the log and descriptors.

Good to know that works! I'll resubmit it as a real patch then.

Quoted 3 lines

But I don't think it's normal behavior. The xHC should accept the alt setting request at the first time. I'm also using the NEC chips, perhaps it's a HW or FW issue but I can't make sure.

Quoted 5 lines

I have a patch to fix this. I wasn't setting the Average TRB Length or Max ESIT fields in the isoc endpoint descriptor. Apparently the NEC chip only needs the avg. TRB length to accept the alternate setting, but the xHCI spec says it's really the max ESIT payload that is used for scheduling, so I've set both.

I've tested the patches and they works. Thanks.

Quoted 7 lines

I'll send the patch in a view minutes. Unfortunately, with my gspca full speed webcam, I hang my machine after installing the interface, when the driver first submits an isochronous URB. It's a "scheduling while atomic" error with a very odd backtrace. But it happens every time I plug in the webcam, so I know it's related to that. Gzipped log file is attached. Ignore the values of the tx_info field in the endpoint, I had a bug with the math in the patch that I've since fixed.

I've checked this issue and figured out the root cause. I used prepare_ring() to check the room for each td in the URB, but not for the whole URB. If a URB carrying multple packets/tds is failed to enqueue due to not enough room on the ring, perhaps some of its tds have already been inserted to the ring before the check failure, which is a mistake. A URB should be inserted to the ring as a whole: either it can be enqueued, or not. Not part of it.

I'll submit the updated patches to fix this issue. It used prepare_ring() in the beginning to guarantee there is enough room for the whole URB. This should fix your issue.

Quoted 13 lines
Quoted 4 lines

Another problem of the isoc transfer is the size of the transfer ring. Currently in xhci_endpoint_init() of xhci-mem.c, the ring allocated for each endpoint just contains one segment, which can hold 64 - 1 = 63 trbs. But the gspca will submit 3 urbs at one time, each consists

Quoted 8 lines

of 32 packets. Each packet needs an isoc TD to carry, and the driver will insert 96 trbs to the ring at one time. It will cause the room_on_ring check failure since the xHC cannot process the trbs in time. After I modify the parameter of xhci_ring_alloc() in xhci_endpoint_init() to allocate 2 segments, the webcam works smoothly. It looks like dynamic ring allocation is necessary for isoc endpoint since it will put multiple trbs on the ring and the fixed size is too small.

Quoted 2 lines

Yes, it looks like dynamic ring resizing is necessary, but feel free to submit your patch for xhci_endpoint_init() for now.

I will submit the patch to allocate bigger ring for isoc endpoints as a temporary workaround.

Andiry Xu