Hi,
I'm trying to talk to a Canon PowerShot A520 via libptp, which uses
libusb. The "ptpcam" app works once, then fails after that until I
dis/re-connect the camera.
open("/proc/bus/usb/001/002", O_RDWR) = 3
ioctl(3, USBDEVFS_CLAIMINTERFACE, 0xbe810c64) = 0
ioctl(3, UI_DEV_DESTROY or USBDEVFS_BULK, 0xbe8109d4) = 16
ioctl(3, UI_DEV_DESTROY or USBDEVFS_BULK, 0xbe8109c4) = -1 ETIMEDOUT
(Connection timed out)
write(2, "ERROR: Could not open session!\nT"..., 56ERROR: Could not open
session!
Try to reset the camera.
) = 56
ioctl(3, USBDEVFS_RELEASEINTERFACE, 0xbe810c68) = 0
I haven't figured out why it behaves like this, but I'm looking at
usbsnoop logs to try and figure out how what the problem is. And I
found this in the logs,
<snippet>
[1796 ms] >>> URB 6 going down >>>
-- URB_FUNCTION_BULK_OR_INTERRUPT_TRANSFER:
PipeHandle = 85bcfe14 [endpoint 0x00000081]
TransferFlags = 00000002 (USBD_TRANSFER_DIRECTION_OUT,
USBD_SHORT_TRANSFER_OK)
TransferBufferLength = 00000040
TransferBuffer = 85d0da98
TransferBufferMDL = 00000000
00000000: 00 00 00 00 00 10 00 00 00 f0 98 02 00 00 00 00
00000010: e8 e6 67 85 b0 1a 5f 85 00 00 99 02 00 00 00 00
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000030: 00 00 00 00 00 00 00 00 d8 1a 5f 85 10 e7 67 85
UrbLink = 00000000
[1807 ms] UsbSnoop - MyInternalIOCTLCompletion(f799fdb0) :
fido=85c8e0d0, Irp=85cc5ab0, Context=862edfa8, IRQL=2
[1807 ms] <<< URB 6 coming back <<<
-- URB_FUNCTION_BULK_OR_INTERRUPT_TRANSFER:
PipeHandle = 85bcfe14 [endpoint 0x00000081]
TransferFlags = 00000003 (USBD_TRANSFER_DIRECTION_IN,
USBD_SHORT_TRANSFER_OK)
TransferBufferLength = 0000000c
TransferBuffer = 85d0da98
TransferBufferMDL = 85c8ad90
00000000: 0c 00 00 00 03 00 01 20 00 00 00 00
UrbLink = 00000000
</snippet>
What puzzles me is that TransferFlags is USBD_TRANSFER_DIRECTION_OUT
going down, and USBD_TRANSFER_DIRECTION_IN coming up. Is this valid?
If so, what would be the corresponding libusb call, usb_bulk_write or
usb_bulk_read?
-Jamie
p.s.
Kernel 2.6.16, libusb 0.1.11, libptp2-1.2.0dr1.
The same build of ptpcam works fine (repeatably without needed to
reconnect) with a Sony DSC-P50 in PTP mode.
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