Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <340a4a81-d4ec-2f42-28ae-49124830157a@linaro.org>
Date:   Tue, 26 Jul 2022 09:01:47 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.12.0
Subject: Re: [PATCH] arm: dts: imx6qdl-vicut1.dtsi: Add backlight-isb node
Content-Language: en-US
To:     David Jander <david@protonic.nl>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Oleksij Rempel <o.rempel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
References: <20220725124813.1001032-1-david@protonic.nl>
 <de68c1e8-447d-f1e9-7885-6a109af1e971@linaro.org>
 <20220726083006.5c65b597@erd992>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20220726083006.5c65b597@erd992>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 26/07/2022 08:30, David Jander wrote:
> On Mon, 25 Jul 2022 22:33:12 +0200
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
> 
>> On 25/07/2022 14:48, David Jander wrote:
>>> On some older hardware models this is needed. It will do no harm if used
>>> with newer models though.
>>>
>>> Signed-off-by: David Jander <david@protonic.nl>
>>> ---
>>>  arch/arm/boot/dts/imx6qdl-vicut1.dtsi | 22 ++++++++++++++++++++++
>>>  1 file changed, 22 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/imx6qdl-vicut1.dtsi b/arch/arm/boot/dts/imx6qdl-vicut1.dtsi
>>> index a1676b5d2980..08d425020088 100644
>>> --- a/arch/arm/boot/dts/imx6qdl-vicut1.dtsi
>>> +++ b/arch/arm/boot/dts/imx6qdl-vicut1.dtsi
>>> @@ -37,6 +37,16 @@ backlight_led: backlight_led {
>>>  		power-supply = <&reg_3v3>;
>>>  	};
>>>  
>>> +	/* only for backwards compatibility with old HW */
>>> +	backlight_isb: backlight_isb {  
>>
>> Node name: backlight-isb
>>
>> I know that other node had underscore, but these are not correct for names.
> 
> I know the names are not correct, but they are in the style of existing node
> names in the same file. Do you want me to change them all, or just this one?
> This change would break existing user-space software though, which is something
> I prefer not to do. Unfortunately both names are relied upon by user-space
> software for almost 10 years now, and changing them will force me to maintain
> off-tree patches that revert these changes.
> I understand the reason for the change though, and if you insist I will do it.

Node names are not ABI, thus any user-space depending on them does it
wrong. Could you link/name which user-space depends on it?

I don't understand why new node is also already a dependency. It's a new
node, there cannot be anything which depends on it before it is being
applied in upstream.


Best regards,
Krzysztof