Re: [PATCH v1 1/3] pwm: dwc: Add 16 channel support for Intel Elkhart Lake

Andy Shevchenko
2024-02-01T12:03:34Z

On Tue, Jan 30, 2024 at 12:30:23PM +0200, Raag Jadav wrote:
> On Sun, Jan 28, 2024 at 04:53:24PM +0200, Andy Shevchenko wrote:
> > On Mon, Jan 22, 2024 at 08:32:36AM +0530, Raag Jadav wrote:
> > > Intel Elkhart Lake PSE includes two instances of PWM as a single PCI
> > > function with 8 channels each. Add support for the remaining channels.

...

> > First option: Always provide driver data (info is never NULL).
>
> Allowing empty driver_data would save us from adding dummy info
> for single instance devices in the future.

Which may be too premature "optimisation". Why? Because if we ever have
something like pci_dev_get_match_data(), the empty will mean NULL, and
we may not get difference between empty and missing one.

> > Second option, have the body of the for-loop be factored to a helper
> > dwc_pwm_init_one() and here
> >
> > if (!info)
> > return dwc_pwm_init_one(..., 1, 0);
> >
> > for (i = 0; i < info->nr; i++) {
> > ret = dwc_pwm_init_one(...);
> > if (ret)
> > return ret;
> > }
>
> Considering above, we're looking at something like this.

As one option, yes.

> static int dwc_pwm_init_one(struct device *dev, void __iomem *base, unsigned int size)
> {
> struct dwc_pwm *dwc;
>
> dwc = dwc_pwm_alloc(dev);
> if (!dwc)
> return -ENOMEM;
>
> dwc->base = base + size;
>
> return devm_pwmchip_add(dev, &dwc->chip);
> }

--
With Best Regards,
Andy Shevchenko