linux-kernel - Re: [PATCH 1/2] i2c: hisi: Add generic GPIO bus recovery support

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Message-ID: <YgEAeOmobDhqRMGx@smile.fi.intel.com>
Date:   Mon, 7 Feb 2022 13:20:24 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yicong Yang <yangyicong@...ilicon.com>
Cc:     jarkko.nikula@...ux.intel.com, mika.westerberg@...ux.intel.com,
        wsa@...nel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, prime.zeng@...ilicon.com,
        linuxarm@...wei.com
Subject: Re: [PATCH 1/2] i2c: hisi: Add generic GPIO bus recovery support

On Mon, Feb 07, 2022 at 01:17:49PM +0200, Andy Shevchenko wrote:
> On Tue, Jan 25, 2022 at 08:49:29PM +0800, Yicong Yang wrote:
> > Add generic GPIO bus recovery support for i2c-hisi driver
> > by registering the recovery information with core provided
> > i2c_generic_scl_recovery() method.
> > 
> > As the SCL/SDA pins are multiplexed with GPIO, we need to
> > switch the pins mux to GPIO before recovery and switch back
> > after recovery. It's implemented by the ACPI method in
> > the i2c_bus_recovery_info->{prepare,unprepare}_recovery()
> > method.
> 
> NAK.
> 
> ACPI has its own resources for that. What is missed is the layer between ACPI
> and pin control.

To be more precise,

https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinconfig-pin-configuration-descriptor-macro

https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinfunction-pin-function-descriptor-macro

https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroup-pin-group-descriptor-macro

https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroupconfig-pin-group-configuration-descriptor-macro

-- 
With Best Regards,
Andy Shevchenko