Re: [PATCH 3/3] pwm: Make capture support optional

[Thierry Reding <thierry.reding@gmail.com>]

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On Mon, May 23, 2022 at 07:45:02PM +0200, Uwe Kleine-König wrote:
> The only code making use of the capture functionality is the sysfs code
> in the PWM framework. I suspect there are no real users and would like to
> deprecate it in favor of the counter framework. So introduce a kconfig
> symbol to remove the capture support and make the sysfs file a stub.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/pwm/Kconfig     | 12 ++++++++++++
>  drivers/pwm/core.c      |  3 ++-
>  drivers/pwm/pwm-sti.c   |  4 ++++
>  drivers/pwm/pwm-stm32.c |  4 ++++
>  drivers/pwm/sysfs.c     |  4 ++++
>  include/linux/pwm.h     |  5 +++++
>  6 files changed, 31 insertions(+), 1 deletion(-)

I've applied patches 1-2 for now, but I'm not convinced about this yet.

The PWM capture is something that's typically useful for applications
served from userspace, which is why only the sysfs implementation
exists. So anything that's based on another framework is likely not
going to have in-kernel users either. Can you specify exactly how this
alternative implementation would look like and how it would be an
improvement over the current implementation?

Thierry

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