linux-toradex.git/drivers/usb/gadget/legacy/Kconfig, branch master

media: Kconfig: cleanup VIDEO_DEV dependencies

2022-03-18T04:58:35+00:00

media Kconfig has two entries associated to V4L API:
VIDEO_DEV and VIDEO_V4L2.

On Kernel 2.6.x, there were two V4L APIs, each one with its own flag.
VIDEO_DEV were meant to:
	1) enable Video4Linux and make its Kconfig options to appear;
	2) it makes the Kernel build the V4L core.

while VIDEO_V4L2 where used to distinguish between drivers that
implement the newer API and drivers that implemented the former one.

With time, such meaning changed, specially after the removal of
all V4L version 1 drivers.

At the current implementation, VIDEO_DEV only does (1): it enables
the media options related to V4L, that now has:

	menu "Video4Linux options"
		visible if VIDEO_DEV

	source "drivers/media/v4l2-core/Kconfig"
	endmenu

but it doesn't affect anymore the V4L core drivers.

The rationale is that the V4L2 core has a "soft" dependency
at the I2C bus, and now requires to select a number of other
Kconfig options:

	config VIDEO_V4L2
		tristate
		depends on (I2C || I2C=n) && VIDEO_DEV
		select RATIONAL
		select VIDEOBUF2_V4L2 if VIDEOBUF2_CORE
		default (I2C || I2C=n) && VIDEO_DEV

In the past, merging them would be tricky, but it seems that it is now
possible to merge those symbols, in order to simplify V4L dependencies.

Let's keep VIDEO_DEV, as this one is used on some make *defconfig
configurations.

Suggested-by: Laurent Pinchart 
Reviewed-by: Laurent Pinchart 
Reviewed-by: Jacopo Mondi 
Reviewed-by: Neil Armstrong  # for meson-vdec & meson-ge2d
Acked-by: Andrzej Pietrasiewicz 
Acked-by: Łukasz Stelmach 
Signed-off-by: Mauro Carvalho Chehab

usb: gadget: uvc: add scatter gather support

2021-07-27T13:59:19+00:00

This patch adds support for scatter gather transfers. If the underlying
gadgets sg_supported == true, then the videeobuf2-dma-sg is used and the
encode routine maps all scatter entries to separate scatterlists for the
usb gadget.

When streaming 1080p with request size of 1024 times 3 bytes top shows a
difference of about 6.4% CPU load applying this patch:

 PID USER      PR  NI    VIRT    RES  %CPU  %MEM     TIME+ S COMMAND

  64 root       0 -20    0.0m   0.0m   7.7   0.0   0:01.25 I [kworker/u5:0-uvcvideo]
  83 root       0 -20    0.0m   0.0m   4.5   0.0   0:03.71 I [kworker/u5:3-uvcvideo]
 307 root     -51   0    0.0m   0.0m   3.8   0.0   0:01.05 S [irq/51-dwc3]

vs.

  64 root       0 -20    0.0m   0.0m   5.8   0.0   0:01.79 I [kworker/u5:0-uvcvideo]
 306 root     -51   0    0.0m   0.0m   3.2   0.0   0:01.97 S [irq/51-dwc3]
  82 root       0 -20    0.0m   0.0m   0.6   0.0   0:01.86 I [kworker/u5:1-uvcvideo]

Signed-off-by: Michael Grzeschik 
Link: https://lore.kernel.org/r/20210628155311.16762-5-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman

usb: raw-gadget: update documentation and Kconfig

2021-01-26T17:38:45+00:00

Update Raw Gadget documentation and Kconfig. Make the description more
precise and clear, fix typos and grammar mistakes, and do other cleanups.

Signed-off-by: Andrey Konovalov 
Link: https://lore.kernel.org/r/f4c650c94ae2b910e38819d51109cd5f0b251a2a.1611429174.git.andreyknvl@google.com
Signed-off-by: Greg Kroah-Hartman

usb: get rid of 'choice' for legacy gadget drivers

2020-03-16T07:36:35+00:00

drivers/usb/gadget/legacy/Kconfig creates a 'choice' inside another
'choice'.

The outer choice: line 17 "USB Gadget precomposed configurations"
The inner choice: line 484 "EHCI Debug Device mode"

I wondered why the whole legacy gadget drivers reside in such a big
choice block.

This dates back to 2003, "[PATCH] USB: fix for multiple definition of
`usb_gadget_get_string'". [1]

At that time, the global function, usb_gadget_get_string(), was linked
into multiple drivers. That was why only one driver was able to become
built-in at the same time.

Later, commit a84d9e5361bc ("usb: gadget: start with libcomposite")
moved usb_gadget_get_string() to a separate module, libcomposite.ko
instead of including usbstring.c from multiple modules.

More and more refactoring was done, and after commit 1bcce939478f
("usb: gadget: multi: convert to new interface of f_mass_storage"),
you can link multiple gadget drivers into vmlinux without causing
multiple definition error.

This is the only user of the nested choice structure ever. Removing
this mess will make some Kconfig cleanups possible.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=fee4cf49a81381e072c063571d1aadbb29207408

Signed-off-by: Masahiro Yamada 
Acked-by: Felipe Balbi 
Link: https://lore.kernel.org/r/20200315154948.26569-1-masahiroy@kernel.org
Signed-off-by: Greg Kroah-Hartman

usb: gadget: add raw-gadget interface

2020-03-15T09:34:48+00:00

USB Raw Gadget is a kernel module that provides a userspace interface for
the USB Gadget subsystem. Essentially it allows to emulate USB devices
from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
currently a strictly debugging feature and shouldn't be used in
production.

Raw Gadget is similar to GadgetFS, but provides a more low-level and
direct access to the USB Gadget layer for the userspace. The key
differences are:

1. Every USB request is passed to the userspace to get a response, while
   GadgetFS responds to some USB requests internally based on the provided
   descriptors. However note, that the UDC driver might respond to some
   requests on its own and never forward them to the Gadget layer.

2. GadgetFS performs some sanity checks on the provided USB descriptors,
   while Raw Gadget allows you to provide arbitrary data as responses to
   USB requests.

3. Raw Gadget provides a way to select a UDC device/driver to bind to,
   while GadgetFS currently binds to the first available UDC.

4. Raw Gadget uses predictable endpoint names (handles) across different
   UDCs (as long as UDCs have enough endpoints of each required transfer
   type).

5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.

Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Andrey Konovalov 
Signed-off-by: Felipe Balbi

usb: gadget: move choice ... endchoice to legacy/Kconfig

2019-12-17T15:24:13+00:00

drivers/usb/gadget/Kconfig includes drivers/usb/gadget/legacy/Kconfig
inside the 'choice' block. The current Kconfig allows this, but I'd
like to discourage this usage.

People tend to mess up the structure without noticing that entire
drivers/usb/gadget/legacy/Kconfig is placed in the choice context.
In fact, legacy/Kconfig mixes up bool and tristate in the choice,
and creates nested choice, etc.

This commit does not change the behavior, but it will help people
notice how badly this Kconfig file is written.

Signed-off-by: Masahiro Yamada 
Link: https://lore.kernel.org/r/20191211073857.16780-1-masahiroy@kernel.org
Signed-off-by: Greg Kroah-Hartman

usb: gadget: Fix Kconfig indentation

2019-11-21T13:39:40+00:00

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
	$ sed -e 's/^        /\t/' -i */Kconfig

Signed-off-by: Krzysztof Kozlowski 
Link: https://lore.kernel.org/r/20191121132905.29248-1-krzk@kernel.org
Signed-off-by: Greg Kroah-Hartman

usb: Fix Kconfig indentation

2019-10-04T12:09:41+00:00

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
    $ sed -e 's/^        /\t/' -i */Kconfig

Signed-off-by: Krzysztof Kozlowski 
Acked-by: Johan Hovold 
Link: https://lore.kernel.org/r/20190923154956.6868-1-krzk@kernel.org
Signed-off-by: Greg Kroah-Hartman

docs: usb: rename files to .rst and add them to drivers-api

2019-06-20T12:28:36+00:00

While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.

A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.

Signed-off-by: Mauro Carvalho Chehab 
Acked-by: Johan Hovold 
Acked-by: Felipe Balbi 
Signed-off-by: Greg Kroah-Hartman

usb: remove redundant 'default n' from Kconfig-s

2019-05-21T08:06:22+00:00

'default n' is the default value for any bool or tristate Kconfig
setting so there is no need to write it explicitly.

Also since commit f467c5640c29 ("kconfig: only write '# CONFIG_FOO
is not set' for visible symbols") the Kconfig behavior is the same
regardless of 'default n' being present or not:

    ...
    One side effect of (and the main motivation for) this change is making
    the following two definitions behave exactly the same:

        config FOO
                bool

        config FOO
                bool
                default n

    With this change, neither of these will generate a
    '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied).
    That might make it clearer to people that a bare 'default n' is
    redundant.
    ...

Signed-off-by: Bartlomiej Zolnierkiewicz 
Signed-off-by: Greg Kroah-Hartman