Re: [PATCH v3 1/4] pwm: Add support for Meson PWM Controller

Neil Armstrong
2016-09-05T09:20:38Z

On 09/05/2016 11:00 AM, Thierry Reding wrote:
> On Mon, Aug 22, 2016 at 05:36:30PM +0200, Neil Armstrong wrote:
>> Add support for the PWM controller found in the Amlogic SoCs.
>> This driver supports the Meson8b and GXBB SoCs.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>> drivers/pwm/Kconfig | 9 +
>> drivers/pwm/Makefile | 1 +
>> drivers/pwm/pwm-meson.c | 528 ++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 538 insertions(+)
>> create mode 100644 drivers/pwm/pwm-meson.c

Hi Thierry,
> Hi Neil,
>
> sorry for taking so long to review this. I had actually started to write
> a review email since I had noticed a couple of slight oddities about the
> driver structure (primarily this was about how channel-specific data was
> split between struct meson_pwm_channel and struct meson_pwm_chip), but I
> ended up making some changes to the driver in order to see what my
> suggestions would look like, and if they would indeed improve things.
> But once I had done that, I thought it a bit pointless to make that into
> review comments and decided to just push what I had done and ask you to
> take a look, and if you had no objections to the changes take the driver
> for a spin to see if it still worked as expected.

Well, thanks ! I was wondering why it took so long, but the result look far best than what I achieved.

The road was very long since the original Amlogic driver...

I will try it out ASAP, but it looks very good for me.
Your changes seems quite obvious, and such rework was necessary.

>
> One other thing I noticed is that your ->get_state() implementation only
> reads the enable state, but from the looks of it it should be possible
> to read period and duty cycle information from hardware as well. I'm not
> going to reject the driver for that reason, just saying that it'd be
> good to have that implemented sometime in the future.

Yes, it was delayed for later since it's not a functional feature, I will certainly push
an update with this later on.

>
> I've pushed my modifications to the driver to the linux-pwm repository:
>
> https://git.kernel.org/cgit/linux/kernel/git/thierry.reding/linux-pwm.git/log/?h=for-next
>
> Alternatively you can also take a look at the for-4.9/drivers branch,
> but they're currently the same thing.

Great, I will give you a functional update ASAP.

> Thierry

Thanks for the review, aww, s/review/rework/ !
Neil
>