Re: [PATCH v7 0/2] pwm: Add GPIO PWM driver

[Stefan Wahren <wahrenst@gmx.net>]

Am 27.06.24 um 08:52 schrieb Uwe Kleine-König:
> Hello,
>
> On Tue, Jun 04, 2024 at 11:00:39PM +0200, Linus Walleij wrote:
>> Add a software PWM which toggles a GPIO from a high-resolution timer.
>>
>> Recent discussions in the Raspberry Pi community revealt that a lot
>> of users still use MMIO userspace tools for GPIO access. One argument
>> for this approach is the lack of a GPIO PWM kernel driver. So this
>> series tries to fill this gap.
>>
>> This continues the work of Vincent Whitchurch [1], which is easier
>> to read and more consequent by rejecting sleeping GPIOs than Nicola's
>> approach [2]. It further takes over where Stefan Wahren left off.
>>
>> I have not looked into the interrupt storm problem mentioned in [3]
>> but instead focused on some real-life tests:
>>
>> The IXP4xx NSLU2 has a speaker connected directly to a GPIO, and I
>> wanted to use this patch to provide a proper beeper for the machine
>> and not have to rely on custom hacks.
>>
>> I added a DTS patch like this:
>>
>> gpio_pwm: pwm {
>>          #pwm-cells = <3>;
>>          compatible = "pwm-gpio";
>>          gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
>> };
>>
>> beeper {
>>          compatible = "pwm-beeper";
>>          pwms = <&gpio_pwm 0 1 0>;
>>          beeper-hz = <1000>;
>> };
> Applied both patches to
> https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next
\o/

Thanks
>
> Thanks
> Uwe