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To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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From:   Michal Simek <michal.simek@xilinx.com>
Subject: Re: [PATCH v4 3/3] pinctrl: Add Xilinx ZynqMP pinctrl driver support
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Date:   Wed, 24 Mar 2021 09:29:12 +0100
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On 3/23/21 2:42 PM, Greg Kroah-Hartman wrote:
> On Wed, Mar 17, 2021 at 01:55:16PM +0530, Sai Krishna Potthuri wrote:
>> Adding pinctrl driver for Xilinx ZynqMP platform.
>> This driver queries pin information from firmware and registers
>> pin control accordingly.
>>
>> Signed-off-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
>> ---
>>  drivers/pinctrl/Kconfig          |   13 +
>>  drivers/pinctrl/Makefile         |    1 +
>>  drivers/pinctrl/pinctrl-zynqmp.c | 1030 ++++++++++++++++++++++++++++++
>>  3 files changed, 1044 insertions(+)
>>  create mode 100644 drivers/pinctrl/pinctrl-zynqmp.c
>>
>> diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
>> index 815095326e2d..25d3c7208975 100644
>> --- a/drivers/pinctrl/Kconfig
>> +++ b/drivers/pinctrl/Kconfig
>> @@ -341,6 +341,19 @@ config PINCTRL_ZYNQ
>>  	help
>>  	  This selects the pinctrl driver for Xilinx Zynq.
>>  
>> +config PINCTRL_ZYNQMP
>> +	bool "Pinctrl driver for Xilinx ZynqMP"
> 
> Please make this work as a module.

The most of pinctrl drivers are builtin modules now which is not excuse
it is just fact.
$ git grep module_pla drivers/pinctrl/ | wc -l
40
$ git grep  builtin_pla drivers/pinctrl/ | wc -l
64

Also at least last 3 pinctrl drivers which have been merged are not modules.
d4c34d09ab03 ("pinctrl: Add RISC-V Canaan Kendryte K210 FPIOA driver")
7e5ea974e61c ("pinctrl: pinctrl-microchip-sgpio: Add pinctrl driver for
Microsemi Serial GPIO")
a68a7844264e ("pinctrl: visconti: Add Toshiba Visconti SoCs pinctrl
support")

None is saying that it can't be done but that cases where you use
pinctrl as module are really very limited. When you start to use pinctrl
and its functionality you need to have it as the part of the kernel to
be to get console, mmc, ethernet, usb, etc.

That's why I would like to know what functionality and use case you have
in mind that this driver should be made module.

Thanks,
Michal