On 2/7/15, 2:27 AM, "Robert P. J. Day" <[email protected]> wrote:
>On Fri, 6 Feb 2015, John Syn wrote: > >> >> On 2/6/15, 11:50 AM, "Robert P. J. Day" <[email protected]> wrote: >> >> > >> > crawling my way through the DTS files for the BBB and i ran across >> >this in am33xx.dtsi: >> > >> > epwmss1: epwmss@48302000 { >> > compatible = "ti,am33xx-pwmss"; >> > reg = <0x48302000 0x10>; >> > ti,hwmods = "epwmss1"; >> > #address-cells = <1>; >> > #size-cells = <1>; >> > status = "disabled"; >> > ranges = <0x48302100 0x48302100 0x80 /* ECAP >>*/ >> > 0x48302180 0x48302180 0x80 /* EQEP >>*/ >> > 0x48302200 0x48302200 0x80>; /* >>EHRPWM >> >*/ >> > >> > ecap1: ecap@48302100 { >> > compatible = "ti,am33xx-ecap"; >> > #pwm-cells = <3>; >> > reg = <0x48302100 0x80>; >> > interrupts = <47>; >> > interrupt-names = "ecap1"; >> > ti,hwmods = "ecap1"; >> > status = "disabled"; >> > }; >> > >> > ehrpwm1: ehrpwm@48302200 { >> > compatible = "ti,am33xx-ehrpwm"; >> > #pwm-cells = <3>; >> > reg = <0x48302200 0x80>; >> > ti,hwmods = "ehrpwm1"; >> > status = "disabled"; >> > }; >> > }; >> > >> > first question ... should there be a node definition for "eqep"? >> >after all, the second triplet in "ranges" is commented with "EQEP", >> >but there is no associated child node for that. i would have expected >> >one. >> > >> > also, based on my understanding of "ranges", the above definition >> >seems to be simply mapping the child address space directly back to >> >the parent address space; i.e., no translation is required. so what is >> >the point? wouldn't the same thing be achieved with a simple: >> > >> > ranges; >> > >> >which specifies that the two address spaces are identical and no >> >address translation is required? >> > >> > or does the above also restrict the mapping to specifically the >> >ranges listed there? >> Hi Robert, >> >> Better to ask this question on the devicetree mailing list: >> Send e-mail to [email protected] with subscribe devicetree in >>the >> body. > > except this isn't a general device tree question, it's specific to >something related to the DT on a BBB, which is why i thought it would >be more appropriate here. and the answer(s) might be helpful to other >BBB users who are curious about device tree stuff as well. > > i'm probably going to have a couple more questions about device >trees related specifically to the BBB -- anyone uninterested is >welcome to ignore them. I wasn¹t being critical, I was only trying to be helpful. There are several people on the DeviceTree mailing list that use BBB, but specifically, Pantelis Antoniou who wrote the cape manager and later the devicetree overlay is someone who could answer your question and I¹m not sure if he monitors this mailing list. Regards, John > >rday > >p.s. i'm trying to clarify a few things for the sake of writing up a >DT tutorial for a couple of my courses. so i want to make sure i >understand it before trying to explain it. :-) > >-- > >======================================================================== >Robert P. J. Day Ottawa, Ontario, CANADA > http://crashcourse.ca > >Twitter: http://twitter.com/rpjday >LinkedIn: http://ca.linkedin.com/in/rpjday >======================================================================== -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
