linux-kernel - Re: [PATCH v5 8/8] ARM: brcmstb: dts: add a reference DTS for Broadcom 7445

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Message-ID: <52E2DD8D.1050609@gmail.com>
Date:	Fri, 24 Jan 2014 13:39:25 -0800
From:	Marc C <marc.ceeeee@...il.com>
To:	Mark Rutland <mark.rutland@....com>
CC:	Christian Daudt <bcm@...thebug.org>, Arnd Bergmann <arnd@...db.de>,
	Florian Fainelli <f.fainelli@...il.com>,
	Matt Porter <matt.porter@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v5 8/8] ARM: brcmstb: dts: add a reference DTS for Broadcom
 7445

Hi Mark,

> As I commented on v3 [1], these are contiguous and can be described with
> a single entry:
>
> memory {
> 	device_type = "memory";
> 	reg = <0x0 0x00000000 0x0 0xc0000000>;
> };
>
> Is there any reason to have three entries?

Oopsies, sorry for missing that.

On BCM7445 and derivatives, there are 3 memory controllers. For each memory controller,
the first 1GB of physical DRAM is mapped to:

* 0x00_0000_0000
* 0x00_4000_0000
* 0x00_8000_0000

The memory controllers aren't interleaved. So, it's possible for the SoC to have a
discontiguous memory-mapping, where a designer chooses not to populate physical DRAM in
the middle.

The 'reg' property was broken-up to have each chunk of memory given a dedicated memblock.

All that said, if you like, I can rework the patch as you've suggested.

Thanks,
Marc C


On 01/24/2014 03:09 AM, Mark Rutland wrote:
> On Wed, Jan 22, 2014 at 03:30:52AM +0000, Marc Carino wrote:
>> Add a sample DTS which will allow bootup of a board populated
>> with the BCM7445 chip.
>>
>> Signed-off-by: Marc Carino <marc.ceeeee@...il.com>
>> Acked-by: Florian Fainelli <f.fainelli@...il.com>
>> ---
>>  arch/arm/boot/dts/bcm7445.dts |  111 +++++++++++++++++++++++++++++++++++++++++
>>  1 files changed, 111 insertions(+), 0 deletions(-)
>>  create mode 100644 arch/arm/boot/dts/bcm7445.dts
>>
>> diff --git a/arch/arm/boot/dts/bcm7445.dts b/arch/arm/boot/dts/bcm7445.dts
>> new file mode 100644
>> index 0000000..ffa3305
>> --- /dev/null
>> +++ b/arch/arm/boot/dts/bcm7445.dts
>> @@ -0,0 +1,111 @@
>> +/dts-v1/;
>> +/include/ "skeleton.dtsi"
>> +
>> +/ {
>> +	#address-cells = <2>;
>> +	#size-cells = <2>;
>> +	model = "Broadcom STB (bcm7445)";
>> +	compatible = "brcm,bcm7445", "brcm,brcmstb";
>> +	interrupt-parent = <&gic>;
>> +
>> +	chosen {};
>> +
>> +	memory {
>> +		device_type = "memory";
>> +		reg = <0x00 0x00000000 0x00 0x40000000>,
>> +		      <0x00 0x40000000 0x00 0x40000000>,
>> +		      <0x00 0x80000000 0x00 0x40000000>;
>> +	};
> 
> As I commented on v3 [1], these are contiguous and can be described with
> a single entry:
> 
> memory {
> 	device_type = "memory";
> 	reg = <0x0 0x00000000 0x0 0xc0000000>;
> };
> 
> Is there any reason to have three entries?
> 
> Thanks,
> Mark.
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-January/225899.html
> 

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