[PATCH V2 1/2] mcx: very basic support for HTKW mcx board

[Igor Grinberg]

Forgot to Cc devicetree-discuss - done now.

On 12/15/11 12:53, Igor Grinberg wrote:
> On 12/15/11 12:17, Cousson, Benoit wrote:
>> Hi Igor,
>>
>> On 12/15/2011 10:51 AM, Igor Grinberg wrote:
>>> On 12/15/11 02:53, Ilya Yanok wrote:
>>>> Very basic support for HTKW mcx board. Able to boot via board-generic
>>>> and ramdisk/initramfs, however most of peripherals is unsupported.
>>>> Produces tons of twl4030 related errors as this board doesn't have
>>>> twl4030 installed.
>>>>
>>>> Signed-off-by: Ilya Yanok<yanok at emcraft.com>
>>>>
>>>> ---
>>>> Changes from V1:
>>>>
>>>>   - device tree moved to the separate patch
>>>>   - iva node is disabled instead of using custom includes
>>>>   - removed bootargs entry
>>>>
>>>>   arch/arm/boot/dts/mcx.dts |   27 +++++++++++++++++++++++++++
>>>>   1 files changed, 27 insertions(+), 0 deletions(-)
>>>>   create mode 100644 arch/arm/boot/dts/mcx.dts
>>>>
>>>> diff --git a/arch/arm/boot/dts/mcx.dts b/arch/arm/boot/dts/mcx.dts
>>>> new file mode 100644
>>>> index 0000000..66b81bd
>>>> --- /dev/null
>>>> +++ b/arch/arm/boot/dts/mcx.dts
>>>> @@ -0,0 +1,27 @@
>>>> +/*
>>>> + * Copyright (C) 2011 Ilya Yanok, EmCraft Systems
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or modify
>>>> + * it under the terms of the GNU General Public License version 2 as
>>>> + * published by the Free Software Foundation.
>>>> + */
>>>> +/dts-v1/;
>>>> +
>>>> +/include/ "omap3.dtsi"
>>>> +
>>>> +/ {
>>>> +    model = "HTKW mcx";
>>>> +    compatible = "htkw,mcx", "ti,omap3";
>>>> +
>>>> +    memory {
>>>> +        device_type = "memory";
>>>> +        reg =<0x80000000 0x10000000>; /* 256 MB */
>>>> +    };
>>>> +
>>>> +    /* AM35xx doesn't have IVA */
>>>> +    soc {
>>>> +        iva {
>>>> +            status = "disabled";
>>>> +        };
>>>> +    };
>>>
>>> I don't get it...
>>> Why SoCs that do not have those IP blocks should poke
>>> their configuration inside the h/w description
>>> (e.g. disable/enable/workaround/hack)?
>>
>> This is indeed the proper way assuming the HW does contain this information. I do not know for this OMAP variant, but this kind of information is not necessarily well exposed inside the HW.
>>
>>> This way, why don't we also disable the PCIe which this SoC does not have?
>>> Of course, I'm exaggerating, but this just does not scale...
>>> Soon you will have a bunch of boards disabling stuff,
>>> that they *do not have natively*...
>>> Why don't generic OMAP3 DT file disable the EMAC?
>>> If we will go this way, we will find ourself fixing it later
>>> and producing the renaming/moving "churn", won't we?
>>
>> You are indeed exaggerating :-)
>>
>> Assuming that device is an OMAP3 variant, it seems OK to me to define it like that. am35xx = omap3 + (new IPs) - (IPs not supported)
> 
> I still haven't seen any real cons about my proposed solution:
> Have include file for each IP, for example IP1/2/3/4...
> omap3 = (include IPs supported: IP1, IP3, IP4)
> am35x = (include IPs supported: IP1, IP2, IP4)
> 
> This way, we will be able to easily support any mixture of those whenever
> TI releases new version of AM/DM3/4/5/6xxx - just include those you have.
> 
> Also, OMAP3 is not a variant of OMAP2, but has several same IPs inside
> (or am I wrong?). Same probably will stand for OMAP4/5/6...
> In my proposed way we can share those IPs without duplicating them.
> 
>>
>> The good point with DT is that you can add or *remove* things from an included file.
> 
> Yes, but I don't think board DT file should do it...
> It contradicts, the DT=="hardware description" statement.
> 
> I also think that it is good thing to try and find a common set of IPs,
> but it can be done by including those and still stay scalable...


-- 
Regards,
Igor.