linux-kernel - [PATCH v4 00/10] Add strobe/flash duration v4l2 ctrl & use it for ov9282

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Message-Id: <20250507-ov9282-flash-strobe-v4-0-72b299c1b7c9@linux.dev>
Date: Wed, 07 May 2025 09:51:29 +0200
From: Richard Leitner <richard.leitner@...ux.dev>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, Lee Jones <lee@...nel.org>, 
 Pavel Machek <pavel@...nel.org>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org, 
 Richard Leitner <richard.leitner@...ux.dev>
Subject: [PATCH v4 00/10] Add strobe/flash duration v4l2 ctrl & use it for
 ov9282

This series adds a new v4l2 controls named "strobe duration" with id
V4L2_CID_FLASH_DURATION. This control enables setting a desired
flash/strobe length/duration in µs.

As a first user of this new control add basic flash/strobe support for
ov9282 sensors using their "hardware strobe output". The duration
calculation is only interpolated from various measurements, as no
documentation was found.

Further flash/strobe-related controls as well as a migration to v4l2-cci
helpers for ov9282 will likely be implemented in future series.

All register addresses/values are based on the OV9281 datasheet v1.53
(january 2019). This series was tested using an ov9281 VisionComponents
camera module.

Signed-off-by: Richard Leitner <richard.leitner@...ux.dev>
---
Changes in v4:
- Fix FLASH_DURATION implementation in v4l2-flash-led-class.c by adding a
  missing brace and enum entry (thanks Sakari)
- Fix format of multiline comment in ov9282.c (thanks Sakari)
- Add missing NULL check in ov9282.c (thanks Sakari)
- Adapt nr_of_controls_hint for v4l2 handler in ov9282.c (thanks Sakari)
- Add patch for implementing try_ctrl for strobe_duration (thanks Sakari)
- Link to v3: https://lore.kernel.org/r/20250429-ov9282-flash-strobe-v3-0-2105ce179952@linux.dev

Changes in v3:
- create separate patch for leds driver changes (thanks Lee)
- Link to v2: https://lore.kernel.org/r/20250314-ov9282-flash-strobe-v2-0-14d7a281342d@linux.dev

Changes in v2:
- remove not needed controls in struct ov9282 (thanks Dave)
- Fix commit message of 3/3 regarding framerate get/set (thanks Dave)
- Add V4L2_CID_FLASH_STROBE_SOURCE impementation to ov9282
- Add new V4L2_CID_FLASH_DURATION control (as suggested by Laurent)
- Use FLASH_DURATION instead of FLASH_TIMEOUT for ov9282
- Link to v1: https://lore.kernel.org/r/20250303-ov9282-flash-strobe-v1-0-0fd57a1564ba@linux.dev

---
Richard Leitner (10):
      media: v4l: ctrls: add a control for flash/strobe duration
      leds: flash: add support for flash/stobe duration
      media: v4l2-flash: add support for flash/strobe duration
      media: v4l2-flash: fix flash_timeout comment
      Documentation: uAPI: media: add V4L2_CID_FLASH_DURATION
      media: i2c: ov9282: add output enable register definitions
      media: i2c: ov9282: add led_mode v4l2 control
      media: i2c: ov9282: add strobe_duration v4l2 control
      media: i2c: ov9282: add strobe_source v4l2 control
      media: i2c: ov9282: implement try_ctrl for strobe_duration

 .../userspace-api/media/v4l/ext-ctrls-flash.rst    |   5 +
 drivers/leds/led-class-flash.c                     |  15 +++
 drivers/media/i2c/ov9282.c                         | 148 ++++++++++++++++++++-
 drivers/media/v4l2-core/v4l2-ctrls-defs.c          |   1 +
 drivers/media/v4l2-core/v4l2-flash-led-class.c     |  25 ++++
 include/linux/led-class-flash.h                    |  18 ++-
 include/uapi/linux/v4l2-controls.h                 |   1 +
 7 files changed, 208 insertions(+), 5 deletions(-)
---
base-commit: 92a09c47464d040866cf2b4cd052bc60555185fb
change-id: 20250303-ov9282-flash-strobe-ac6bd00c9de6
prerequisite-change-id: 20250225-b4-ov9282-gain-ef1cdaba5bfd:v1
prerequisite-patch-id: 86f2582378ff7095ab65ce4bb25a143eb639e840
prerequisite-patch-id: b06eb6ec697aaf0b3155b4b2370f171d0d304ae2
prerequisite-patch-id: b123047d71bfb9b93f743bbdd6893d5a98495801

Best regards,
-- 
Richard Leitner <richard.leitner@...ux.dev>