d692522577
This patch reworks the videobuffer management logic present in the UVC webcam gadget and ports it to use the "more apt" videobuf2 framework for video buffer management. To support routing video data captured from a real V4L2 video capture device with a "zero copy" operation on videobuffers (as they pass from the V4L2 domain to UVC domain via a user-space application), we need to support USER_PTR IO method at the UVC gadget side. So the V4L2 capture device driver can still continue to use MMAP IO method and now the user-space application can just pass a pointer to the video buffers being dequeued from the V4L2 device side while queueing them at the UVC gadget end. This ensures that we have a "zero-copy" design as the videobuffers pass from the V4L2 capture device to the UVC gadget. Note that there will still be a need to apply UVC specific payload headers on top of each UVC payload data, which will still require a copy operation to be performed in the 'encode' routines of the UVC gadget. This patch also addresses one issue found out while porting the UVC gadget to videobuf2 framework: - In case the usb requests queued by the gadget get completed with a status of -ESHUTDOWN (disconnected from host), the queue of videobuf2 should be cancelled to ensure that the application space daemon is not left in a state waiting for a vb2 to be successfully absorbed at the USB side. Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> |
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.. | ||
atm | ||
c67x00 | ||
chipidea | ||
class | ||
core | ||
dwc3 | ||
early | ||
gadget | ||
host | ||
image | ||
misc | ||
mon | ||
musb | ||
phy | ||
renesas_usbhs | ||
serial | ||
storage | ||
wusbcore | ||
Kconfig | ||
Makefile | ||
README | ||
usb-common.c | ||
usb-skeleton.c |
To understand all the Linux-USB framework, you'll use these resources: * This source code. This is necessarily an evolving work, and includes kerneldoc that should help you get a current overview. ("make pdfdocs", and then look at "usb.pdf" for host side and "gadget.pdf" for peripheral side.) Also, Documentation/usb has more information. * The USB 2.0 specification (from www.usb.org), with supplements such as those for USB OTG and the various device classes. The USB specification has a good overview chapter, and USB peripherals conform to the widely known "Chapter 9". * Chip specifications for USB controllers. Examples include host controllers (on PCs, servers, and more); peripheral controllers (in devices with Linux firmware, like printers or cell phones); and hard-wired peripherals like Ethernet adapters. * Specifications for other protocols implemented by USB peripheral functions. Some are vendor-specific; others are vendor-neutral but just standardized outside of the www.usb.org team. Here is a list of what each subdirectory here is, and what is contained in them. core/ - This is for the core USB host code, including the usbfs files and the hub class driver ("khubd"). host/ - This is for USB host controller drivers. This includes UHCI, OHCI, EHCI, and others that might be used with more specialized "embedded" systems. gadget/ - This is for USB peripheral controller drivers and the various gadget drivers which talk to them. Individual USB driver directories. A new driver should be added to the first subdirectory in the list below that it fits into. image/ - This is for still image drivers, like scanners or digital cameras. ../input/ - This is for any driver that uses the input subsystem, like keyboard, mice, touchscreens, tablets, etc. ../media/ - This is for multimedia drivers, like video cameras, radios, and any other drivers that talk to the v4l subsystem. ../net/ - This is for network drivers. serial/ - This is for USB to serial drivers. storage/ - This is for USB mass-storage drivers. class/ - This is for all USB device drivers that do not fit into any of the above categories, and work for a range of USB Class specified devices. misc/ - This is for all USB device drivers that do not fit into any of the above categories.