linux-kernel - Re: [PATCH v2 1/3] ARM: imx: Allow user to disable pinctrl

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Message-ID: <1ff005f8-384d-465e-9597-b6d5fd903862@roeck-us.net>
Date: Tue, 26 Nov 2024 15:53:01 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Esben Haabendal <esben@...nix.com>, Russell King <linux@...linux.org.uk>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, Dong Aisheng <aisheng.dong@....com>,
 Jacky Bai <ping.bai@....com>, Arnd Bergmann <arnd@...db.de>,
 Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
 linux-arm-kernel@...ts.infradead.org, imx@...ts.linux.dev,
 linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
 Fabio Estevam <festevam@...x.de>
Subject: Re: [PATCH v2 1/3] ARM: imx: Allow user to disable pinctrl

On 11/26/24 13:24, Linus Walleij wrote:
> On Tue, Nov 26, 2024 at 5:17 PM Guenter Roeck <linux@...ck-us.net> wrote:
>> On Mon, May 06, 2024 at 12:23:53PM +0200, Esben Haabendal wrote:
> 
>>> Making pinctrl drivers and subsequently the pinctrl framework
>>> user-controllable, allows building a kernel without this.
>>> While in many (most) cases, this could make the system unbootable, it
>>> does allow building smaller kernels for those situations where picntrl
>>> is not needed.
>>>
>>> One such situation is when building a kernel for NXP LS1021A systems,
>>> which does not have run-time controllable pinctrl, so pinctrl framework
>>> and drivers are 100% dead-weight.
>>>
>>>
>>> Signed-off-by: Esben Haabendal <esben@...nix.com>
>>
>> This patch didn't update default configurations, meaning PINCTRL is now
>> disabled by affected configurations such as imx_v4_v5_defconfig or
>> imx_v6_v7_defconfig, making pretty much all imx platforms non-bootable
>> unless the default configuration is changed manually.
> 
> Since the patch tries to add default selects for all drivers I suspect this
> oneliner is the culprit:
> 
> @@ -6,7 +6,6 @@ menuconfig ARCH_MXC
>          select CLKSRC_IMX_GPT
>          select GENERIC_IRQ_CHIP
>          select GPIOLIB
> -       select PINCTRL
>          select PM_OPP if PM
>          select SOC_BUS
>          select SRAM
> 
> Should we just add that one line back?
> 

My understanding (which may be wrong) is that being able to disable
PINCTRL was the whole point of the patch.

Fabio submitted a patch enabling PINCTRL for imx_v4_v5_defconfig and
imx_v6_v7_defconfig explicitly [1]. I don't know if that fixes the
problem for good - I see CONFIG_ARCH_MXC in other configurations as
well.

Guenter

---
[1] https://lore.kernel.org/imx/d718ddd2-d473-4455-b21a-15024e46787c@roeck-us.net/T/#mc71dc21d99e0b013c5ce46c0d90940fd8806ae9a