Re: [PATCH] dt-bindings: soc: imx8mp-media-blk-ctrl: Add LDB into DT example

From: Marek Vasut <marex@denx.de>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Rob Herring <robh@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	NXP Linux Team <linux-imx@nxp.com>,
	Paul Elder <paul.elder@ideasonboard.com>,
	Peng Fan <peng.fan@nxp.com>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH] dt-bindings: soc: imx8mp-media-blk-ctrl: Add LDB into DT example
Date: Fri, 8 Jul 2022 17:32:48 +0200	[thread overview]
Message-ID: <f0583d3e-eef1-7f97-9e06-e8dcd2859e9d@denx.de> (raw)
In-Reply-To: <eb8cede8-6493-c116-29eb-0303c1871239@linaro.org>

On 7/4/22 10:00, Krzysztof Kozlowski wrote:
> On 01/07/2022 10:06, Marek Vasut wrote:
>> In the local patch I have to imx8mp.dtsi , the simple-mfd had to be
>> added for the ldb bridge child node to bind.
>>
>>> 'simple-mfd' is saying the child has 0 dependence on the parent. IMO,
>>> 'syscon' contradicts that, but that's an all to common pattern. You are
>>> saying all the clocks (or any other resources) in the parent can be off
>>> and the LDB bridge is still functional.
>>
>> The bridge itself should work even if the block control is clocked off.
>> The block controller apb (register) clock have to be enabled only when
>> accessing these two LDB registers, which should be handled by runtime
>> PM. Or what am I missing here ?
> 
> If I understand correctly, you need the device's APB clocks to be
> enabled to use the child device? You have a dependency between child and
> parent, so it is not a simple-mfd.

OK, then ... what is it ? Some sort of hint would be helpful.