Re: [PATCH 2/2] net, thunder, bgx: Add support for ACPI binding.

[Tomasz Nowicki]

On 07.08.2015 13:56, Robert Richter wrote:
> On 07.08.15 12:52:41, Tomasz Nowicki wrote:
> > On 07.08.2015 12:43, Robert Richter wrote:
> > > On 07.08.15 10:09:04, Tomasz Nowicki wrote:
> > > > On 07.08.2015 02:33, David Daney wrote:
> > >
> > > ...
> > >
> > > > > +#else
> > > > > +
> > > > > +static int bgx_init_acpi_phy(struct bgx *bgx)
> > > > > +{
> > > > > +	return -ENODEV;
> > > > > +}
> > > > > +
> > > > > +#endif /* CONFIG_ACPI */
> > > > > +
> > > > >   #if IS_ENABLED(CONFIG_OF_MDIO)
> > > > >
> > > > >   static int bgx_init_of_phy(struct bgx *bgx)
> > > > > @@ -882,7 +1010,12 @@ static int bgx_init_of_phy(struct bgx *bgx)
> > > > >
> > > > >   static int bgx_init_phy(struct bgx *bgx)
> > > > >   {
> > > > > -	return bgx_init_of_phy(bgx);
> > > > > +	int err = bgx_init_of_phy(bgx);
> > > > > +
> > > > > +	if (err != -ENODEV)
> > > > > +		return err;
> > > > > +
> > > > > +	return bgx_init_acpi_phy(bgx);
> > > > >   }
> > > >
> > > > If kernel can work with DT and ACPI (both compiled in), it should take only
> > > > one path instead of probing DT and ACPI sequentially. How about:
> > > >
> > > > @@ -902,10 +925,9 @@ static int bgx_probe(struct pci_dev *pdev, const struct
> > > > pci_device_id *ent)
> > > >   	bgx_vnic[bgx->bgx_id] = bgx;
> > > >   	bgx_get_qlm_mode(bgx);
> > > >
> > > > -	snprintf(bgx_sel, 5, "bgx%d", bgx->bgx_id);
> > > > -	np = of_find_node_by_name(NULL, bgx_sel);
> > > > -	if (np)
> > > > -		bgx_init_of(bgx, np);
> > > > +	err = acpi_disabled ? bgx_init_of_phy(bgx) : bgx_init_acpi_phy(bgx);
> > > > +	if (err)
> > > > +		goto err_enable;
> > > >
> > > >   	bgx_init_hw(bgx);
> > >
> > > I would not pollute bgx_probe() with acpi and dt specifics, and instead
> > > keep bgx_init_phy(). The typical design pattern for this is:
> > >
> > > static int bgx_init_phy(struct bgx *bgx)
> > > {
> > > #ifdef CONFIG_ACPI
> > >          if (!acpi_disabled)
> > >                  return bgx_init_acpi_phy(bgx);
> > > #endif
> > >          return bgx_init_of_phy(bgx);
> > > }
> > >
> > > This adds acpi runtime detection (acpi=no), does not call dt code in
> > > case of acpi, and saves the #else for bgx_init_acpi_phy().
> >
> > I am fine with keeping it in bgx_init_phy(), however we can drop there
> > #ifdefs since both of bgx_init_{acpi,of}_phy calls have empty stub for !ACPI
> > and !OF case. Like that:
> >
> > static int bgx_init_phy(struct bgx *bgx)
> > {
> >
> >          if (!acpi_disabled)
> >                  return bgx_init_acpi_phy(bgx);
> > 	else
> >          	return bgx_init_of_phy(bgx);
> > }
>
> As said, keeping it in #ifdefs makes the empty stub function for !acpi
> obsolete, which makes the code smaller and better readable. This style
> is common practice in the kernel. Apart from that, the 'else' should
> be dropped as it is useless.

I would't say the code is better readable (bgx_init_of_phy has still two 
stubs) but this is just cosmetic, my point was to use run time detection 
using acpi_disabled.

Tomasz
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