[PATCH 0/4] ARM: boot: mxs: Add On-Chip RAM
Shawn Guo
shawnguo at kernel.org
Fri Oct 21 08:03:36 PDT 2016
On Fri, Oct 21, 2016 at 04:05:59PM +0200, Stefan Wahren wrote:
> Am 21.10.2016 um 15:53 schrieb Shawn Guo:
> > On Tue, Sep 13, 2016 at 05:51:02PM +0000, Stefan Wahren wrote:
> >> The i.MX23 / i.MX28 have a small amount of On-Chip RAM which is also necessary
> >> for suspend to RAM and standby mode. But before we need to remove the fake reg
> >> properties of all internal bus nodes as discussed in this thread [1].
> >>
> >> This patch series requires Fabio Estevam's recent series "ARM: dts: imx23:
> >> Remove skeleton.dtsi inclusion" [2].
> >>
> >> [1] - https://marc.info/?l=devicetree&m=146139948426520&w=2
> > The page cannot be reached. I would like to understand the
> > background for this change.
>
> Strange, because i don't have any problems while clicking on the URL.
>
> It's an older discussion on the devicetree / kernel newbie mailing list
> with subject "strange dtc errors after adding sram node". Arnd suggested
> in the discussion to remove the reg property from the ahb node.
>
> Please try this one: http://www.spinics.net/lists/newbies/msg57652.html
If you go through 'Table 4-1. Address Map for i.MX28' of MCIMX28RM, you
should be able to find there are 3 AHB buses: ahb at 0, ahb at 80080000 and
ahb at c0000000. The ocram goes to ahb at 0. The following change should be
the right one for ocram addition.
diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 0ad893bf5f43..8e5718df06b2 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -47,6 +47,19 @@
};
};
+ ahb at 0 {
+ compatible = "simple-bus";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ reg = <0x0 0x80000000>;
+ ranges;
+
+ ocram: sram at 0 {
+ compatible = "mmio-sram";
+ reg = <0x0 0x20000>;
+ };
+ };
+
apb at 80000000 {
compatible = "simple-bus";
#address-cells = <1>;
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