linux-kernel - Re: [PATCH 1/4] dt-bindings: Document new common property: has-inaccessible-regs

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Message-ID: <c303a5f3-4283-445e-9e0e-053fab32a468@kernel.org>
Date: Sun, 30 Nov 2025 09:17:49 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Richard Weinberger <richard@....at>
Cc: linux-kernel <linux-kernel@...r.kernel.org>,
 linux-omap <linux-omap@...r.kernel.org>,
 devicetree <devicetree@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>,
 Lee Jones <lee@...nel.org>, dakr <dakr@...nel.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Mark Brown <broonie@...nel.org>, tony <tony@...mide.com>,
 rogerq <rogerq@...nel.org>, khilman <khilman@...libre.com>,
 Andreas Kemnade <andreas@...nade.info>, aaro koskinen
 <aaro.koskinen@....fi>, Conor Dooley <conor+dt@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, robh <robh@...nel.org>
Subject: Re: [PATCH 1/4] dt-bindings: Document new common property:
 has-inaccessible-regs

On 29/11/2025 16:56, Richard Weinberger wrote:
> ----- Ursprüngliche Mail -----
>> Von: "Krzysztof Kozlowski" <krzk@...nel.org>
>>> So, drivers like ti,pbias-dra7 or ti,dra7xx-phy-gmii-sel touch only registers
>>> they know about and this works well.
>>> But syscon manages the whole register map via regmap, and regmap exposes it all
>>> via debugfs.
>>>
>>> What solution do you propose?
>>> Splitting reg = <0x0 0x1400> into many tiny fractions and not using an mfd
>>> anymore?
>>
>> Fix the driver. In your case, the syscon driver.
> 
> Please help me to understand what the desired behavior of the driver is.
> 
> Currently syscon creates one regmap for everything and passes this regmap
> to the individual syscon users.
> These users have to know what offset within the regmap is their playground.
> If I understand correctly, it would be better if every syscon user would register their own regmap?

I don't think so. This device driver, so the syscon, creates the regmap
and knows EXACTLY which registers are valid or not. It is not
responsibility of the consumer to tell the syscon what this syscon is.
Syscon knows that...

Best regards,
Krzysztof