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.
Regards,
John
>
>rday
>
>--
>
>========================================================================
>Robert P. J. Day Ottawa, Ontario, CANADA
> http://crashcourse.ca
>
>Twitter: http://twitter.com/rpjday
>LinkedIn: http://ca.linkedin.com/in/rpjday
>========================================================================
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