From mboxrd@z Thu Jan  1 00:00:00 1970
From: swarren@wwwdotorg.org (Stephen Warren)
Date: Thu, 04 Oct 2012 09:41:06 -0600
Subject: [PATCH] ARM: kirkwood: DT board setup for Network Space v2 and
 parents
In-Reply-To: <20121004075335.GY31897@kw.sim.vm.gnt>
References: <1349277270-24962-1-git-send-email-simon.guinot@sequanux.org>
 <20121003154310.GI11837@lunn.ch> <20121003220916.GW31897@kw.sim.vm.gnt>
 <20121004055443.GK21046@lunn.ch> <20121004075335.GY31897@kw.sim.vm.gnt>
Message-ID: <506DAE12.7000003@wwwdotorg.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 10/04/2012 01:53 AM, Simon Guinot wrote:
> On Thu, Oct 04, 2012 at 07:54:43AM +0200, Andrew Lunn wrote:
>>>>> --- a/arch/arm/mach-kirkwood/board-dt.c +++
>>>>> b/arch/arm/mach-kirkwood/board-dt.c @@ -96,6 +96,11 @@
>>>>> static void __init kirkwood_dt_init(void) if
>>>>> (of_machine_is_compatible("keymile,km_kirkwood")) 
>>>>> km_kirkwood_init();
>>>>> 
>>>>> +	if (of_machine_is_compatible("lacie,inetspace_v2") || +
>>>>> of_machine_is_compatible("lacie,netspace_v2") || +
>>>>> of_machine_is_compatible("lacie,netspace_max_v2")) +
>>>>> ns2_init(); + of_platform_populate(NULL,
>>>>> kirkwood_dt_match_table, kirkwood_auxdata_lookup, NULL);
>>>> 
>>>> I'm not a DT policy expert. Could this be one compatibility
>>>> string for all the boards? Maybe ask on the DT mainline
>>>> list?
>>> 
>>> Maybe I could use "lacie,ns2_common" as a compatibility string.
>>> But this does not match any existing device. I don't know if it
>>> is correct.
>> 
>> Hi Simon
>> 
>> I did a bit of looking around. For kirkwood, we already have two 
>> boards sharing the same compatibility string. kirkwood-dns320.dts
>> and kirkwood-dns325.dts both have dlink,dns-kirkwood and this is
>> what the board-dt.c matches on.
>> 
>> For the tegra20 soc, all boards match on nvidia,tegra20, and that
>> is the only compatibility string in board-dt-tegra20.c.

nvidia,tegra20 is the compatible value for the SoC itself, so
naturally any Tegra20-based board has that.

>> So i don't see any problem having just one compatibility string
>> here.
>> 
>> The question is, what is the appropriate name. How common is
>> this common C code? Are there ns2 where this C code is not
>> appropriate. One thing to remember is that most of this C code
>> will soon disappear and become DT. All the mpp will be replaced
>> with pinctrl in 3.8. I hope we can get the Ethernet setup in DT
>> as well. You are working on ns2_led, so all the C code will be
>> replaced by DT. So all we are really left with is power off GPIO
>> handling.
>> 
>> So i think the danger of using lacie,ns2_common, and then finding
>> it does not work with some other ns2 device is quite low.

lacie,ns2_common doesn't sound like a HW description, but rather a SW
invention. DT should be describing purely the HW. If there's no common
HW between these compatible boards (which seems unlikely), then there
shouldn't be a shared compatible value.

>> What do you think?
> 
> The status for this ns2 boards is more or less end-of-life. I mean,
> this boards are no longer in production. So I think it is safe to
> consider the code inside board-ns2.c as common and shareable
> between ns2, is2 and ns2max.
> 
> Once this file will be removed, the compatibility checks will be
> removed as well. But one could easily forget to remove the useless
> compatibility string "lacie,ns2_common" from the dts...

If that value is added to the DT, it should not be removed, and the
kernel should continue to support it indefinitely.