Hi Alexey,
On 12/10/24 09:40, Alexey Charkov wrote:
Hi Naoki,
On Tue, Dec 10, 2024 at 3:30 AM FUKAUMI Naoki <naoki@xxxxxxxxx> wrote:
Hi,
Thanks for your review!
On 12/10/24 01:32, Dragan Simic wrote:
Hello Fukaumi,
On 2024-12-09 13:51, FUKAUMI Naoki wrote:
fix pwm period to match with vendor kernel[1].
Instead of simply referring to the downstream vendor kernel, in this
specific case the reasons for adjusting the fan PWM parameters should
be explained by referring to the actual fan setup you're using, the
observed fan RPM behavior, etc.
original commit message is:
| arm64: dts: rockchip: modify fan pwm period to 60us
| Reduce pwm frequency to 16.6 KHz for a larger adjustable range of
AO3416 mosfet.
I have no knowledge about this kind of things. Is quoting this message
enough?
I think it would be better to expand a bit to make sure the commit
message explains the whole rationale without too much extra digging.
Something like this:
arm64: dts: rockchip: Use a longer PWM period for the fan on Radxa ROCK 5C
The fan on Radxa ROCK 5C is driven via an AO3416 MOSFET, which has a
total switch-on time of 0,6us and a total switch-off time of 6us [1],
meaning that the current PWM period of just 10us is too short for
fine-grained fan speed control. Increase the PWM period to 60us, so
that the switch-on and switch-off time of the MOSFET fall within a
more reasonable ~10% of the full period, thus making lower PWM duty
cycles meaningful.
[1] https://www.aosmd.com/pdfs/datasheet/AO3416.pdf
Thank you so much!
Best regards,
--
FUKAUMI Naoki
Radxa Computer (Shenzhen) Co., Ltd.
Best regards,
Alexey
