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Date: Tue, 13 Feb 2024 09:57:20 +0100
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Subject: Re: [PATCH v1 07/14] dt-bindings: lcdif: Do not require power-domains
 for i.MX6ULL
Content-Language: en-US
To: Sebastian Reichel <sre@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
 Sascha Hauer <s.hauer@pengutronix.de>, Fabio Estevam <festevam@gmail.com>,
 Pengutronix Kernel Team <kernel@pengutronix.de>,
 NXP Linux Team <linux-imx@nxp.com>, Dong Aisheng <aisheng.dong@nxp.com>,
 Linus Walleij <linus.walleij@linaro.org>,
 Dmitry Torokhov <dmitry.torokhov@gmail.com>, Mark Brown
 <broonie@kernel.org>, linux-arm-kernel@lists.infradead.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240210012114.489102-1-sre@kernel.org>
 <20240210012114.489102-8-sre@kernel.org>
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From: Stefan Wahren <wahrenst@gmx.net>
In-Reply-To: <khwsxrpj5fgxl7ukiur2tdyy7a6d6h6zryc5z2h7o6f7k3b32p@cjqsmdbocfpe>
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Hi Sebastian,

Am 13.02.24 um 00:10 schrieb Sebastian Reichel:
> Hi Stefan,
>
> On Mon, Feb 12, 2024 at 08:20:35PM +0100, Stefan Wahren wrote:
>> Am 10.02.24 um 02:18 schrieb Sebastian Reichel:
>>> i.MX6UL(L) uses "fsl,imx6sx-lcdif" as fallback compatible string,
>>> but has only very lightweight DISPLAY power domain. Its DISPLAY
>>> power domain is not supported by the binding / Linux kernel at
>>> the moment. Since the current setup is working, let's remove the
>>> power-domain from being required for that platform to fix the warning
>>> printed by CHECK_DTBS=3Dy.
>> i'm not sure this is a good idea. In case i.MX6UL(L) is different from
>> i.MX6SX here, then it should have a different compatible.
> It already has. The i.MX6UL(L) compatible looks like this:
>
> compatible =3D "fsl,imx6ul-lcdif", "fsl,imx6sx-lcdif"
>
> So the i.MX6SX one is just a fallback compatible. But the current
> requirement for power-domains affects i.MX6UL(L), since it says
> the compatible only needs to contain "fsl,imx6sx-lcdif" somewhere
> to make power-domains mandatory.
thanks, i misunderstood the commit message. I thought this was a
i.MX6UL(L) specific issue and the i.MX6SX is slightly different. In the
past the fallback compatible was sometimes abused.

So everything makes sense now.
> Note, that the kernel driver does not use "fsl,imx6ul-lcdif", so
> the hardware itself is indeed compatible.
>
> -- Sebastian
>
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