[RFC 00/19] Async sub-notifiers and how to use them

Sakari Ailus
2017-07-18T19:04:04Z

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Hi folks,

This RFC patchset achieves a number of things which I've put to the same
patchset for they need to be show together to demonstrate the use cases.

I don't really intend this to compete with Niklas's patchset but much of
the problem area addressed by the two is the same.

Comments would be welcome.

- Add AS3645A LED flash class driver.

- Add async notifiers (by Niklas).

- V4L2 sub-device node registration is moved to take place at the same time
with the registration of the sub-device itself. With this change,
sub-device node registration behaviour is aligned with video node
registration.

- The former is made possible by moving the bound() callback after
sub-device registration.

- As all the device node registration and link creation is done as the
respective devices are probed, there is no longer dependency to the
notifier complete callback which as itself is seen problematic. The
complete callback still exists but there's no need to use it, pending
changes in individual drivers.

See:
<URL:http://www.spinics.net/lists/linux-media/msg118323.html>

As a result, if a part of the media device fails to initialise because it
is e.g. physically broken, it will be possible to use what works.

- Finally, the use of the async sub-notifier is hidden in the framework and
all a driver (such as smiapp) needs to do is to call
v4l2_subdev_fwnode_reference_parse_sensor_common() in its probe()
function to find out the associated devices (lens and flash). This
approach makes it possible to later on to rework the sub-notifier
implementation without touching driver code. Endpoints can be parsed
similarly by simply calling v4l2_subdev_fwnode_endpoints_parse() for
driver's probe function.

The patches depend on this branch currently:

<URL:https://git.linuxtv.org/sailus/media_tree.git/log/?h=as3645a-leds-base>

It's essentially the V4L2 flash class patches I've posted earlier today and
a stash of fwnode property API improvements.

Niklas Söderlund (1):
v4l: async: add subnotifier registration for subdevices

Sakari Ailus (18):
device property: Introduce fwnode_property_get_reference_args
dt: bindings: Add a binding for flash devices associated to a sensor
dt: bindings: Add lens-focus binding for image sensors
leds: as3645a: Add LED flash class driver
leds: as3645a: Separate flash and indicator LED sub-devices
v4l: fwnode: Support generic parsing of graph endpoints in V4L2
arm: dts: omap3: N9/N950: Add AS3645A camera flash
v4l2-fwnode: Add conveniences function for parsing generic references
v4l2-fwnode: Add convenience function for parsing common external refs
v4l2-async: Register sub-devices before calling bound callback
v4l2-subdev: Support registering V4L2 sub-device nodes one by one
v4l2-device: Register sub-device nodes at sub-device registration time
omap3isp: Move sub-device link creation to notifier bound callback
omap3isp: Initialise "crashed" media entity enum in probe
omap3isp: Move media device registration to probe
omap3isp: Drop the async notifier callback
v4l2-fwnode: Add abstracted sub-device notifiers
smiapp: Add support for flash and lens devices

.../devicetree/bindings/media/video-interfaces.txt | 10 +
Documentation/media/kapi/v4l2-subdev.rst | 20 +
MAINTAINERS | 6 +
arch/arm/boot/dts/omap3-n9.dts | 1 +
arch/arm/boot/dts/omap3-n950-n9.dtsi | 14 +
arch/arm/boot/dts/omap3-n950.dts | 1 +
drivers/acpi/property.c | 27 +
drivers/base/property.c | 12 +
drivers/leds/Kconfig | 8 +
drivers/leds/Makefile | 1 +
drivers/leds/leds-as3645a.c | 762 +++++++++++++++++++++
drivers/media/i2c/smiapp/smiapp-core.c | 5 +
drivers/media/platform/omap3isp/isp.c | 144 ++--
drivers/media/platform/omap3isp/isp.h | 3 -
drivers/media/v4l2-core/v4l2-async.c | 96 ++-
drivers/media/v4l2-core/v4l2-device.c | 139 ++--
drivers/media/v4l2-core/v4l2-fwnode.c | 174 +++++
drivers/media/v4l2-core/v4l2-subdev.c | 44 +-
drivers/of/property.c | 31 +
include/linux/fwnode.h | 19 +
include/linux/property.h | 4 +
include/media/v4l2-async.h | 26 +-
include/media/v4l2-fwnode.h | 21 +
include/media/v4l2-subdev.h | 11 +
24 files changed, 1388 insertions(+), 191 deletions(-)
create mode 100644 drivers/leds/leds-as3645a.c

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