Re: [PATCH 5/8] mfd: Add ST's Low Power Controller driver

Lee Jones
2014-12-15T13:50:59Z

On Mon, 15 Dec 2014, Arnd Bergmann wrote:

> On Monday 15 December 2014 11:25:35 Lee Jones wrote:
> > + ret = of_property_read_u32(np, "st,lpc-mode", &mode);
> > + if (ret) {
> > + dev_err(&pdev->dev, "An LPC mode must be selected\n");
> > + return ret;
> > + }
> > +
> > + switch (mode) {
> > + case ST_LPC_MODE_RTC:
> > + cell->name = "st-lpc-rtc";
> > + break;
> > + case ST_LPC_MODE_WDT:
> > + cell->name = "st-lpc-wdt";
> > + break;
> > + default:
> > + dev_err(&pdev->dev, "Unsupported mode: %d\n", mode);
> > + return ret;
> > + }
> > +
> > + /* Pass resources though to selected child device. */
> > + cell->resources = pdev->resource;
> > + cell->num_resources = pdev->num_resources;
> > +
> > + ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO,
> > + cell, 1, NULL, 0, NULL);
> >
>
> I don't think it's necessary to have the MFD node if only one of the
> two modes can be used based on a DT property. It should be enough
> to have both the rtc and the wdt driver list the same compatible
> string and check the property in the probe function to decide if
> they want to drive the device or not:

I tried that and it didn't work. Only one driver probed.

> ret = of_property_read_u32(np, "st,lpc-mode", &mode);
> if (!ret && mode != ST_LPC_MODE_RTC)
> return -ENXIO
>
>
> Arnd

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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