[PATCH] s5pv210: Change the base ram address to 0x3000'0000

[kmpark@infradead.org (Kyungmin Park)]

On Mon, May 31, 2010 at 9:39 AM, Ben Dooks <ben-linux@fluff.org> wrote:
> On Fri, May 28, 2010 at 11:35:59AM +0900, Kyungmin Park wrote:
>> s5pc110 (aka s5pv210) has 2 DRAM port and used it both usually.
>> Assume DMC0 starts with 0x2000'0000 with 128MiB.
>> DMC1 starts with 0x4000'0000 with 128MiB.
>> Note that DMC1 has to start address 0x4000'0000 at least.
>>
>> Then there's too much memory hole 0x1800'0000 (128MiB + 256MiB)
>>
>> To reduce memory waste, the DMC0 start with 0x3000'0000.
>>
>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>> ---
>> diff --git a/arch/arm/mach-s5pv210/Makefile.boot b/arch/arm/mach-s5pv210/Makefile.boot
>> index ff90aa1..b0909e3 100644
>> --- a/arch/arm/mach-s5pv210/Makefile.boot
>> +++ b/arch/arm/mach-s5pv210/Makefile.boot
>> @@ -1,2 +1,2 @@
>> - ? zreladdr-y ? ? ? ?:= 0x20008000
>> -params_phys-y ? ? ? ?:= 0x20000100
>> + ? zreladdr-y ? ? ? ?:= 0x30008000
>> +params_phys-y ? ? ? ?:= 0x30000100
>
> Apart from the technical comments that have been in this thread, I would
> like to share notes about making changes like these that affect the entire
> SoC kernel build.
>
> Firstly, changing this effects the rest of the users, not everyone is
> using the same device with same layout. This configuration boots on
> both S5PC110 and S5PV210 devices. Some of these _have_ to support 1GiB
> of memory. Some of them have their bootloaders programemd to start at
> 0x20... So please think of how this will affect everyone else.
>
> Secondly, if you have thought about point 1, then please let us know in
> the commit messages. ?The commit message isn't just a log of what the
> patch does, it can also be used to show any necessary working about what
> is happening and side-effects of it.
>
> Thirdly, the kernel's default configuration for a SoC/arch isn't meant to
> be the best-fit for your board(s) or development practicies. It is meant
> to cover as many devices as possible, to allow build testing and to have
> something that people can test with. If it is not the most efficient on
> the board, then make your own defconfig that is a best fit for your
> purposes.
>
> So, sometimes when this sort of change is required there may be a case of
> making it configurable so that your own defconfig/boardconfig can select
> it for your own projects.
>
>
> Please keep in mind that other people have/are using the kernel and that
> some changes have an affect on other projects as well as your own. This
> is why user-space facing changes are the most debated and difficult to
> do, kernel internals shift quite easily, whilst the data exported to
> userspace is kept as stable as possible.

Definitely I agree with your opinions. and that's why I change it to
0x3000'0000.
when we start the project. chip vendor guides us to use the
0x3000'0000. at that time there's some reason to use this address. As
I know. but some time later they change it to 0x2000'0000.
But we already setup and develop the all environment as 0x3000'0000.
it's also difficult to change it to 0x2000'0000.

Thank you,
Kyungmin Park