Re: [PATCH 2/5] arm: dts: lpc32xx: fix improper usage of ranges property

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Tuesday 13 October 2015 18:51:24 Vladimir Zapolskiy wrote:
> On 13.10.2015 15:44, Arnd Bergmann wrote:
> > I don't get it. What kind of errors do you see? The existing
> > version looks cleaner than the new one, as it only translates
> > the MMIO areas that are actually used.
> > 
> 
> The problem is found when I add PL175 device node to lpc32xx.dtsi and
> expand the node in my board file. The external memory controller manages
> up to 4 memory devices, which by means of the controller are mapped into
> physical memory starting from address 0xe0000000.
> 
> Below are my declarations, similar to one found in lpc18xx.dtsi.
> 
> lpc32xx.dtsi change common for all LPC32xx boards:
> 
> emc: emc@31080000 {
> 	compatible = "arm,pl175", "arm,primecell";
> 	reg = <0x31080000 0x1000>;
> 	clocks = <&scf LPC32XX_CLK_DDRAM>;
> 	clock-names = "mpmcclk";
> 
> 	#address-cells = <1>;
> 	#size-cells = <1>;
> 	ranges = <0 0xe0000000 0x01000000>,
> 		 <1 0xe1000000 0x01000000>,
> 		 <2 0xe2000000 0x01000000>,
> 		 <3 0xe3000000 0x01000000>;
> 	status = "disabled";
> };
> 

Ok, got it.

> Support of EMC device node will be added to lpc32xx.dtsi, when this kind
> of problem is fixed.

As I see it, the problem is that you now have ranges that are not
for devices inside of the device but that are external. As the
memory-controller node needs both its own registers and the translation
for the external ones, we unfortunately can't just put it in the root
node, which would avoid the issue.

Instead, I would suggest adding a range for the 0xe0000000 area.


	Arnd
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