Re: [PATCH v2 10/10] pwm: Add Raspberry Pi Firmware based PWM bus

[Andy Shevchenko]

On Thu, Oct 22, 2020 at 9:05 PM Nicolas Saenz Julienne
<nsaenzjulienne@xxxxxxx> wrote:
>
> Adds support to control the PWM bus available in official Raspberry Pi
> PoE HAT. Only RPi's co-processor has access to it, so commands have to
> be sent through RPi's firmware mailbox interface.

>  drivers/pwm/pwm-raspberrypi.c | 221 ++++++++++++++++++++++++++++++++++

Name is completely confusing.
Please, make it unique enough to understand that this is exactly the
device it serves for.

For example, pwm-rpi-poe is better.

...

> + *  - Only normal polarity

Can't it be emulated? Isn't it 100% - duty cycle % ?


> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>

...

> +       ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,
> +                                   &msg, sizeof(msg));
> +       if (ret)
> +               return ret;

> +       else if (msg.ret)

Redundant 'else'

> +               return -EIO;

...

> +       ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,
> +                                   &msg, sizeof(msg));
> +       if (ret)
> +               return ret;

> +       else if (msg.ret)

Ditto.

> +               return -EIO;

...

> +       firmware_node = of_get_parent(dev->of_node);
> +       if (!firmware_node) {
> +               dev_err(dev, "Missing firmware node\n");
> +               return -ENOENT;
> +       }
> +
> +       firmware = rpi_firmware_get(firmware_node);
> +       of_node_put(firmware_node);
> +       if (!firmware)
> +               return -EPROBE_DEFER;

Looks like a hack.

...

> +       ret = pwmchip_remove(&rpipwm->chip);
> +       if (!ret)
> +               rpi_firmware_put(rpipwm->firmware);
> +
> +       return ret;

Can't you use the usual pattern?

  ret = ...
  if (ret)
    return ret;
  ...
  return 0;

-- 
With Best Regards,
Andy Shevchenko