Hi Phil,
Am 02.02.24 um 14:19 schrieb Phil Howard:
On Sun, 28 Jan 2024 at 16:37, Stefan Wahren <wahrenst@xxxxxxx> 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.
*Thank you* for picking this up. I've been stuck down by covid but am aiming
to build and test this on a Pi 5 (with a gpio chip over PCIe) to see if it runs-
though I am fully expecting a PIO solution (using the Pi 5s RP1) to handle
PWM in this case, and hope to rely upon this gpio-pwm module for previous
iterations.
i hope you are doing well.
There will be small functional changes in V4. Since this series based on
Linux 6.8 and there is no RPi 5 mainline support, you will need to apply
it on top of rpi-6.8.y.
Should i wait for your test results (no pressure) before sending V4?
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].
The work has been tested on a Raspberry Pi 3 B+ and a cheap logic
analyzer.
V3:
- rebase on top of v6.8-pwm-next
- cherry-pick improvements from Nicola's series
- try to address Uwe's, Linus' and Andy's comments
- try to avoid GPIO glitches during probe
- fix pwm_gpio_remove()
- some code clean up's and comments
V2:
- Rename gpio to gpios in binding
- Calculate next expiry from expected current expiry rather than "now"
- Only change configuration after current period ends
- Implement get_state()
- Add error message for probe failures
- Stop PWM before unregister
[1] - https://lore.kernel.org/all/20200915135445.al75xmjxudj2rgcp@xxxxxxxx/T/
[2] - https://lore.kernel.org/all/20201205214353.xapax46tt5snzd2v@xxxxxxxxxxxxxxxxxxx/
Nicola Di Lieto (1):
dt-bindings: pwm: Add pwm-gpio
Vincent Whitchurch (1):
pwm: Add GPIO PWM driver
.../devicetree/bindings/pwm/pwm-gpio.yaml | 42 ++++
drivers/pwm/Kconfig | 11 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-gpio.c | 221 ++++++++++++++++++
4 files changed, 275 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/pwm-gpio.yaml
create mode 100644 drivers/pwm/pwm-gpio.c
--
2.34.1
