[PATCH 04/14] ARM: dts: armada-375: Fixup bootrom DT warning

Hello,

On Thu, 10 Nov 2016 10:36:47 +0100, Gregory CLEMENT wrote:

quoted

quoted

-		bootrom {
+		bootrom at 0 {
 			compatible = "marvell,bootrom";
 			reg = <MBUS_ID(0x01, 0x1d) 0 0x100000>;  

I am still not sure whether this "0" unit address is correct compared
to the reg property being passed.  

I chose to use the adress register inside the window memory.

Which I think is bogus, as my example below highlighted.

quoted

A good example of why I'm worried is the sa-sram case:

+		crypto_sram0: sa-sram0 at 0 {
 			compatible = "mmio-sram";
 			reg = <MBUS_ID(0x09, 0x09) 0 0x800>;

+		crypto_sram1: sa-sram1 at 0 {
 			compatible = "mmio-sram";
 			reg = <MBUS_ID(0x09, 0x05) 0 0x800>;

The node names should be just "sram" without a number. Indeed for UARTs
for example, you use uart at XYZ, uart at ABC and not uart0 at XYZ and
uart1 at ABC. But then, if you do that, with your scheme, you end up with
both nodes named sa-sram at 0.

Which clearly shows that the way you set this unit-address is not
correct: those two devices are mapped at completely different
locations, but you end up with an identical unit address.

I have no idea what is the rule for setting the unit address in this
case, but I'm pretty sure the rule you've chosen is not good.  

I don't know if there is an existing rules for this case. But I see your
concern. What I propose then is to expose the memory windows ID by
adding the target and the attributes like this:

		crypto_sram0: sa-sram at 09_09_0 {
 			compatible = "mmio-sram";
  			reg = <MBUS_ID(0x09, 0x09) 0 0x800>;


		crypto_sram1: sa-sram at 09_05_0 {
  			compatible = "mmio-sram";
  			reg = <MBUS_ID(0x09, 0x05) 0 0x800>;

I have no idea if 09_05_0 is considered a valid unit address. Indeed
the _ character in an address looks a bit weird.

I guess we need guidance from the DT binding maintainers on this, since
it's really a matter of interpreting what "unit address" means in
relation to the value of the "reg" property.

Rob, Mark?

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com