Re: [PATCH v1 00/55] media: Add a helper for obtaining the clock producer

From: Michael Riesch
Date: Sat Jun 21 2025 - 10:28:59 EST

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Hi Mehdi,

Thanks for your work!

On 6/19/25 19:58, Mehdi Djait wrote:
> Hello everyone,
>
> Here is my v1 for the new helper v4l2_devm_sensor_clk_get()
>
> Any testing of the patches is GREATLY APPRECIATED! Especially the two
> drivers with the special ACPI case:
> 1) OV8865
> 2) OV2680
>
>
> Background
> ----------
>
> A reference to the clock producer is not available to the kernel
> in ACPI-based platforms but the sensor drivers still need them.
>
> devm_clk_get() will return an error and the probe function will fail.
>
>
> Solution
> --------
>
> Introduce a generic helper for v4l2 sensor drivers on both DT- and ACPI-based
> platforms.

Out of curiosity: How is this problem specific to V4L2? Does one need a
similar helper in other subsystems?

Best regards,
Michael

>
> This helper behaves the same as clk_get_optional() except where there is
> no clock producer like in ACPI-based platforms.
>
> For ACPI-based platforms the function will read the "clock-frequency"
> ACPI _DSD property and register a fixed frequency clock with the frequency
> indicated in the property.
>
>
> Solution for special ACPI case
> ------------------------------
>
> This function also handles the special ACPI-based system case where:
>
> 1) The clock-frequency _DSD property is present.
> 2) A reference to the clock producer is present, where the clock is provided
> by a camera sensor PMIC driver (e.g. int3472/tps68470.c)
>
> In this case try to set the clock-frequency value to the provided clock.
>
>
> RFC History
> -----------
>
> RFC v4 -> RFC v5:
> Suggested by Arnd Bergmann:
> - removed IS_REACHABLE(CONFIG_COMMON_CLK). IS_REACHABLE() is actually
> discouraged [1]. COFIG_COMMON_CLK is a bool, so IS_ENABLED() will be the
> right solution here
> Suggested by Hans de Goede:
> - added handling for the special ACPI-based system case, where
> both a reference to the clock-provider and the _DSD
> clock-frequency are present.
> - updated the function's kernel-doc and the commit msg
> to mention this special case.
> Link RFC v4: https://lore.kernel.org/linux-media/20250321130329.342236-1-mehdi.djait@xxxxxxxxxxxxxxx/
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/Documentation/kbuild/kconfig-language.rst?h=next-20250513&id=700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea
>
> RFC v3 -> RFC v4:
> Suggested by Laurent:
> - removed the #ifdef to use IS_REACHABLE(CONFIG_COMMON_CLK)
> - changed to kasprintf() to allocate the clk name when id is NULL and
> used the __free(kfree) scope-based cleanup helper when
> defining the variable to hold the allocated name
> Link v3: https://lore.kernel.org/linux-media/20250321093814.18159-1-mehdi.djait@xxxxxxxxxxxxxxx/
>
> RFC v2 -> RFC v3:
> - Added #ifdef CONFIG_COMMON_CLK for the ACPI case
> Link v2: https://lore.kernel.org/linux-media/20250310122305.209534-1-mehdi.djait@xxxxxxxxxxxxxxx/
>
> RFC v1 -> RFC v2:
> Suggested by Sakari:
> - removed clk_name
> - removed the IS_ERR() check
> - improved the kernel-doc comment and commit msg
> Link v1: https://lore.kernel.org/linux-media/20250227092643.113939-1-mehdi.djait@xxxxxxxxxxxxxxx
>
> Mehdi Djait (55):
> media: v4l2-common: Add a helper for obtaining the clock producer
> Documentation: media: camera-sensor: Mention
> v4l2_devm_sensor_clk_get() for obtaining the clock
> media: i2c: ar0521: Use the v4l2 helper for obtaining the clock
> media: i2c: ds90ub913: Use the v4l2 helper for obtaining the clock
> media: i2c: ds90ub960: Use the v4l2 helper for obtaining the clock
> media: i2c: et8ek8: Use the v4l2 helper for obtaining the clock
> media: i2c: gc05a2: Use the v4l2 helper for obtaining the clock
> media: i2c: gc08a3: Use the v4l2 helper for obtaining the clock
> media: i2c: gc2145: Use the v4l2 helper for obtaining the clock
> media: i2c: hi846: Use the v4l2 helper for obtaining the clock
> media: i2c: imx214: Use the v4l2 helper for obtaining the clock
> media: i2c: imx219: Use the v4l2 helper for obtaining the clock
> media: i2c: imx283: Use the v4l2 helper for obtaining the clock
> media: i2c: imx290: Use the v4l2 helper for obtaining the clock
> media: i2c: imx296: Use the v4l2 helper for obtaining the clock
> media: i2c: imx334: Use the v4l2 helper for obtaining the clock
> media: i2c: imx335: Use the v4l2 helper for obtaining the clock
> media: i2c: imx412: Use the v4l2 helper for obtaining the clock
> media: i2c: imx415: Use the v4l2 helper for obtaining the clock
> media: i2c: max2175: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9m001: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9m111: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9m114: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9p031: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9t112: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9v032: Use the v4l2 helper for obtaining the clock
> media: i2c: mt9v111: Use the v4l2 helper for obtaining the clock
> media: i2c: ov02a10: Use the v4l2 helper for obtaining the clock
> media: i2c: ov2659: Use the v4l2 helper for obtaining the clock
> media: i2c: ov2685: Use the v4l2 helper for obtaining the clock
> media: i2c: ov5640: Use the v4l2 helper for obtaining the clock
> media: i2c: ov5645: Use the v4l2 helper for obtaining the clock
> media: i2c: ov5647: Use the v4l2 helper for obtaining the clock
> media: i2c: ov5648: Use the v4l2 helper for obtaining the clock
> media: i2c: ov5695: Use the v4l2 helper for obtaining the clock
> media: i2c: ov64a40: Use the v4l2 helper for obtaining the clock
> media: i2c: ov6650: Use the v4l2 helper for obtaining the clock
> media: i2c: ov7740: Use the v4l2 helper for obtaining the clock
> media: i2c: ov8856: Use the v4l2 helper for obtaining the clock
> media: i2c: ov8858: Use the v4l2 helper for obtaining the clock
> media: i2c: ov8865: Use the v4l2 helper for obtaining the clock
> media: i2c: ov9282: Use the v4l2 helper for obtaining the clock
> media: i2c: ov9640: Use the v4l2 helper for obtaining the clock
> media: i2c: ov9650: Use the v4l2 helper for obtaining the clock
> media: i2c: s5c73m3: Use the v4l2 helper for obtaining the clock
> media: i2c: s5k5baf: Use the v4l2 helper for obtaining the clock
> media: i2c: s5k6a3: Use the v4l2 helper for obtaining the clock
> media: i2c: st-mipid02: Use the v4l2 helper for obtaining the clock
> media: i2c: tc358743: Use the v4l2 helper for obtaining the clock
> media: i2c: tc358746: Use the v4l2 helper for obtaining the clock
> media: i2c: thp7312: Use the v4l2 helper for obtaining the clock
> media: i2c: vd55g1: Use the v4l2 helper for obtaining the clock
> media: i2c: vd56g3: Use the v4l2 helper for obtaining the clock
> media: i2c: vgxy61: Use the v4l2 helper for obtaining the clock
> media: i2c: ov2680: Use the v4l2 helper for obtaining the clock
>
> .../driver-api/media/camera-sensor.rst | 3 +-
> drivers/media/i2c/ar0521.c | 2 +-
> drivers/media/i2c/ds90ub913.c | 2 +-
> drivers/media/i2c/ds90ub960.c | 2 +-
> drivers/media/i2c/et8ek8/et8ek8_driver.c | 2 +-
> drivers/media/i2c/gc05a2.c | 2 +-
> drivers/media/i2c/gc08a3.c | 2 +-
> drivers/media/i2c/gc2145.c | 2 +-
> drivers/media/i2c/hi846.c | 2 +-
> drivers/media/i2c/imx214.c | 2 +-
> drivers/media/i2c/imx219.c | 2 +-
> drivers/media/i2c/imx283.c | 2 +-
> drivers/media/i2c/imx290.c | 2 +-
> drivers/media/i2c/imx296.c | 2 +-
> drivers/media/i2c/imx334.c | 2 +-
> drivers/media/i2c/imx335.c | 2 +-
> drivers/media/i2c/imx412.c | 2 +-
> drivers/media/i2c/imx415.c | 2 +-
> drivers/media/i2c/max2175.c | 2 +-
> drivers/media/i2c/mt9m001.c | 2 +-
> drivers/media/i2c/mt9m111.c | 2 +-
> drivers/media/i2c/mt9m114.c | 2 +-
> drivers/media/i2c/mt9p031.c | 2 +-
> drivers/media/i2c/mt9t112.c | 2 +-
> drivers/media/i2c/mt9v032.c | 2 +-
> drivers/media/i2c/mt9v111.c | 2 +-
> drivers/media/i2c/ov02a10.c | 2 +-
> drivers/media/i2c/ov2659.c | 2 +-
> drivers/media/i2c/ov2680.c | 27 +++-------
> drivers/media/i2c/ov2685.c | 2 +-
> drivers/media/i2c/ov5640.c | 2 +-
> drivers/media/i2c/ov5645.c | 2 +-
> drivers/media/i2c/ov5647.c | 2 +-
> drivers/media/i2c/ov5648.c | 2 +-
> drivers/media/i2c/ov5695.c | 2 +-
> drivers/media/i2c/ov64a40.c | 2 +-
> drivers/media/i2c/ov6650.c | 2 +-
> drivers/media/i2c/ov7740.c | 2 +-
> drivers/media/i2c/ov8856.c | 2 +-
> drivers/media/i2c/ov8858.c | 2 +-
> drivers/media/i2c/ov8865.c | 32 ++----------
> drivers/media/i2c/ov9282.c | 2 +-
> drivers/media/i2c/ov9640.c | 2 +-
> drivers/media/i2c/ov9650.c | 2 +-
> drivers/media/i2c/s5c73m3/s5c73m3-core.c | 2 +-
> drivers/media/i2c/s5k5baf.c | 2 +-
> drivers/media/i2c/s5k6a3.c | 2 +-
> drivers/media/i2c/st-mipid02.c | 2 +-
> drivers/media/i2c/tc358743.c | 2 +-
> drivers/media/i2c/tc358746.c | 2 +-
> drivers/media/i2c/thp7312.c | 2 +-
> drivers/media/i2c/vd55g1.c | 2 +-
> drivers/media/i2c/vd56g3.c | 2 +-
> drivers/media/i2c/vgxy61.c | 2 +-
> drivers/media/v4l2-core/v4l2-common.c | 49 +++++++++++++++++++
> include/media/v4l2-common.h | 25 ++++++++++
> 56 files changed, 136 insertions(+), 102 deletions(-)
>

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Previous message: Tetsuo Handa: "Re: [syzbot] [ocfs2?] possible deadlock in ocfs2_try_remove_refcount_tree"
In reply to: Laurent Pinchart: "Re: [PATCH v1 00/55] media: Add a helper for obtaining the clock producer"
Next in thread: Hans de Goede: "Re: [PATCH v1 00/55] media: Add a helper for obtaining the clock producer"
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