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Date: Tue, 19 Dec 2023 16:40:48 +0100
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 4/4] dts: iot2050: Support IOT2050-SM variant
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To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
 Nishanth Menon <nm@ti.com>, Vignesh Raghavendra <vigneshr@ti.com>,
 Tero Kristo <kristo@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Bao Cheng Su <baocheng.su@siemens.com>,
 Chao Zeng <chao.zeng@siemens.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 devicetree@vger.kernel.org, Li Hua Qian <huaqian.li@siemens.com>
References: <cover.1702917360.git.jan.kiszka@siemens.com>
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 <f6241b58-202e-4624-ae83-ce52fc286edf@linaro.org>
From: Jan Kiszka <jan.kiszka@siemens.com>
In-Reply-To: <f6241b58-202e-4624-ae83-ce52fc286edf@linaro.org>
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On 19.12.23 16:39, Krzysztof Kozlowski wrote:
> On 19/12/2023 16:37, Jan Kiszka wrote:
>>>>>
>>>>> You have label for that... Somehow all these nodes are half-baked,
>>>>> without all the expected properties and now you call node name as ABI.
>>>>> The node name is not the ABI.
>>>>
>>>> Well, existing userspace uses those names, and adding the properties
>>>> would break that interface. Now, does Linux do that?
>>>
>>> I don't think you understood the concept. There is no change for
>>> userspace. Same interface, same names. No ABI break.
>>
>> I do understand the impact very well:
>> open("/sys/class/leds/user-led1-red") has to work for all the variants,
>> consistently and backward-compatible for userspace.
> 
> And it will. The name is the same.

Nope, it's not - I tried that already :)

root@iot2050-debian:~# ls -l /sys/class/leds/
total 0
lrwxrwxrwx 1 root root 0 Dec 19 09:49 green:indicator -> ../../devices/platform/leds/leds/green:indicator
lrwxrwxrwx 1 root root 0 Dec 19 09:49 green:status -> ../../devices/platform/leds/leds/green:status
lrwxrwxrwx 1 root root 0 Dec 19 09:49 mmc0:: -> ../../devices/platform/bus@100000/4fa0000.mmc/leds/mmc0::
lrwxrwxrwx 1 root root 0 Dec 19 09:49 mmc1:: -> ../../devices/platform/bus@100000/4f80000.mmc/leds/mmc1::
lrwxrwxrwx 1 root root 0 Dec 19 09:49 red:indicator -> ../../devices/platform/leds/leds/red:indicator
lrwxrwxrwx 1 root root 0 Dec 19 09:49 red:indicator_1 -> ../../devices/platform/leds/leds/red:indicator_1
lrwxrwxrwx 1 root root 0 Dec 19 09:49 red:indicator_2 -> ../../devices/platform/leds/leds/red:indicator_2
lrwxrwxrwx 1 root root 0 Dec 19 09:49 red:status -> ../../devices/platform/leds/leds/red:status

Jan

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