2013/4/8 Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>: > Hi Jean-Philippe, > > On Wednesday 06 March 2013 14:21:14 jean-philippe francois wrote: >> Hi, >> >> The company I work for is doing USB cameras, for which >> I wrote the drivers (out of tree). > > Just out of curiosity, was there any shortcoming in the UVC specification that > pushed your company to implementing a vendor protocol ? The main shortcoming in retrospect IMO is the absence of any raw format. However this shortcoming was not the main force behind going with our own protocol. - when we started (on windows) around 2002 we were not aware of UVC. - when I started to develop a driver for the linux kernel, there was no UVC stack. However the reason we did not switch to an UVC firmware is that our streaming processor (Cypress FX2LP) hasn't the capability to inspect and edit the video coming from the sensor to inject the necessary start and end code. > >> Raw camera data are transferred using isochronous transfer. >> >> However when plugging the camera on an USB3 port, xhci spits the >> following messages on URB submission : >> >> [ 1704.989785] xhci_hcd 0000:01:00.0: ERROR Transfer event TRB DMA ptr >> not part of current TD >> >> I submit 4 urbs, each containing 16 ISO frames, and have 61 or 62 >> messages in the dmesg output. >> >> In addition, stopping the stream definitely confuse the driver or >> chip, which is considered dead by the usb core (cf logs). >> >> USB3 host is an asmedia ASM1042. >> >> Please find attached the dmesg output, and the output of lsusb -v for >> the device. >> >> This is with 3.8.2 opensuse Kernel Of The Day >> >> Regards, >> Jean-Philippe François >> >> PS : I am not subscribed to the list, can I be cc'ed in the reply ? > > -- > Regards, > > Laurent Pinchart > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
