On Monday 08 December 2014 08:55:20 Ray Jui wrote: > > On 12/8/2014 3:22 AM, Arnd Bergmann wrote: > > On Sunday 07 December 2014 18:38:32 Ray Jui wrote: > >> +Required properties: > >> + > >> +- compatible: > >> + Currently supported Cygnus GPIO controllers include: > >> + "brcm,cygnus-ccm-gpio": ChipcommonG GPIO controller > >> + "brcm,cygnus-asiu-gpio": ASIU GPIO controller > >> + "brcm,cygnus-crmu-gpio": CRMU GPIO controller > > > > How different are these? If they are almost the same, would it > > be better to use the same compatible string for all of them and > > describe the differences in extra properties? > > > > If they are rather different, maybe you should have a separate > > binding and driver for each? > > > > Arnd > > > They are quite similar with the following minor differences: > 1) ChipcommonG GPIO controller uses a separate register block > (0x0301d164) to control drive stregnth > 2) Cannot control drive strength for the CMRU GPIO This can be deducted from having one or two register blocks I assume. > 3) CRMU GPIO controller's interrupt is not connected to GIC of A9. > Currently that's taken care of by using a "no-interrupt" device tree > property No need for this property even, just see if there is an "interrupts" property or not. > I can change to use the common compatible string "brcm,cygnus-gpio". > With an introduction of property "no-drv-stregnth" which should be set > for CRMU GPIO controller. Ok. > For ChipcommonG GPIO, it will have a second > register block defined, so we'll know to use that second register block > for drive strength configuration. For the rest, we assume normal drive > strength configuration (i.e., ASIU in our case). Maybe see if something older than cygnus was already using a compatible gpio controller and then use the name of that. > Looking at this again, it looks like the "no-interrupt" property is > really redundant. For GPIO controller without interrupt connected to A9, > we can simply leave its interrupt properties not defined. I'll get rid > of it along with the above changes. Right. Arnd -- 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
