On Thu, Oct 02, 2014 at 04:02:58PM +0200, Linus Walleij wrote: > On Wed, Sep 24, 2014 at 2:40 PM, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > > On Wed, Sep 24, 2014 at 01:23:09PM +0200, Linus Walleij wrote: > > >> I haven't got to reviewing the driver, but this looks just wrong. > >> > >> Have the magic numbers in the driver. > >> > >> Use strings to describe functions, not integers. > > > > Interrupts, clocks, gpios, dma channels, nearly everything in the device tree is > > arbitrarily numbered. Instead of "irq-i2c0" we have <0 36 IRQ_TYPE_LEVEL_HIGH> > > in the device tree. These numbers can be resolved efficiently in the > > driver by shifting them to get a bitmask or by adding them as offset to > > a register base. > > Why do you want to make pinctrl different? > > Because pin control is about combining groups of pins with > certain functions. > > > Thanks to the recently > > introduced defines in the device trees these numbers are not magic at > > all anymore. > > Yeah that is good but not what I'm after here. > > >> We need to move toward standardized device tree bindings > >> for this stuff, and that means using strings, not magic > >> numbers. > > > > Agreed for standardized device tree bindings, but not for using strings. > > What is the alternative? Device Tree is very much about strings, > as is shown by the pin config bindings. The alternative is to use numbers. The majority of SoCs have a bit field per pad which is used for muxing the pad to different functions. The natural way to describe this is a pair of numbers: <pad-number> <function-number>. The pad number can normally be directly translated into a register offset and the function number to a value written to that register. This is true for most SoCs I know of and makes it very easy to generate code for and to prove for correctness of both the code and the device tree. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
