On Tue, Sep 29, 2015 at 06:28:11PM +0100, Rob Herring wrote: > On Tue, Sep 22, 2015 at 12:52 PM, Marc Zyngier <marc.zyng...@arm.com> wrote: > > of_parse_phandle_with_args() is slightly inflexible as it doesn't > > allow the (unusual) case where the #*-cells property is not defined. > > In order to support this, introduce of_parse_phandle_with_opt_args() > > which assumes that #*-cells is zero when it is not defined, > > zero or cell_count - 1? > > I would be okay with always assuming zero rather than being an error > if that simplifies things. It is not really the kernel's job to be a > dtb validator.
In most other cases #$foo-cells is strictly required, and you could get bizarre behaviour in drivers by assuming 0. It would be good to keep a warning for those. That said, I guess drivers should be checking that the number of cells is what they expect, so maybe any warnings should exist there. > Also, I assume this was done for some compatibility? Yup. There are existing users without #msi-cells (which is effectively the same as #msi-cells = 0). > In general, we should be explicit, so "#msi-cells = <0>" should be > recommended and we should update dts files if they are not. I agree, assuming we retain support for existing DTBs which lack #msi-cells. Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
