Re: [RFC PATCH for Juno 1/2] net: smsc911x add support for probing from ACPI

[Arnd Bergmann <arnd@arndb.de>]

On Monday 01 September 2014 18:04:47 Catalin Marinas wrote:
> On Mon, Sep 01, 2014 at 04:06:00PM +0100, Hanjun Guo wrote:
> > +#ifdef CONFIG_ACPI
> > +/* Configure some sensible defaults for ACPI mode */
> > +static int smsc911x_probe_config_acpi(struct smsc911x_platform_config *config,
> > +                                 acpi_handle *ahandle)
> > +{
> > +     if (!ahandle)
> > +             return -ENOSYS;
> > +
> > +     config->phy_interface = PHY_INTERFACE_MODE_MII;
> > +
> > +     config->flags |= SMSC911X_USE_32BIT;
> > +
> > +     config->irq_polarity = SMSC911X_IRQ_POLARITY_ACTIVE_HIGH;
> > +
> > +     config->irq_type = SMSC911X_IRQ_TYPE_PUSH_PULL;
> > +
> > +     return 0;
> > +}
> > +#else
> 
> I don't like this and it shows issues we have with ACPI on certain ARM
> platforms. You hard-code these values to match the Juno platform. What
> if we get another SoC which has different configuration here? For DT, we
> have the smsc911x_probe_config_dt() which reads the relevant information
> from DT. I think this kind of configuration would be more suitable as
> _DSD properties and sharing the similar names with DT (but we go back to
> the question about who's in charge of the _DSD properties).

Good point, I totally missed that.

There is of course the possibility to set those values based on the
acpi_device_id, but that is exactly the part that _DSD is trying to
avoid.

> >  static int smsc911x_drv_probe(struct platform_device *pdev)
> >  {
> >       struct device_node *np = pdev->dev.of_node;
> > +     acpi_handle *ahandle = ACPI_HANDLE(&pdev->dev);
> >       struct net_device *dev;
> >       struct smsc911x_data *pdata;
> >       struct smsc911x_platform_config *config = dev_get_platdata(&pdev->dev);
> > @@ -2436,6 +2464,9 @@ static int smsc911x_drv_probe(struct platform_device *pdev)
> >       }
> >  
> >       retval = smsc911x_probe_config_dt(&pdata->config, np);
> > +     if (retval)
> > +             retval = smsc911x_probe_config_acpi(&pdata->config, ahandle);
> > +
> 
> In most of the ACPI patches so far we check for ACPI first with DT as a
> fall-back if ACPI is not enabled. This changes here.

Does this really make a difference?

> I would prefer
> something which probes only ACPI if the ACPI is enabled (run-time, not
> config) otherwise DT only. E.g.

(example missing?)

I think we should have the equivalent of of_have_populated_dt(), to
check whether acpi is being used to boot, and have that new function
be hardcoded to zero in case of !IS_ENABLED(CONFIG_ACPI).

	Arnd