linux-kernel - Re: [PATCH 6/6] i2c: designware: Use PCI PSP driver for communication

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Message-ID: <Y+9fXzby07f6mY59@smile.fi.intel.com>
Date:   Fri, 17 Feb 2023 13:05:03 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Limonciello, Mario" <mario.limonciello@....com>
Cc:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Jan Dąbroś <jsd@...ihalf.com>,
        Grzegorz Bernacki <gjb@...ihalf.com>,
        Thomas Rijo-john <Rijo-john.Thomas@....com>,
        Lendacky Thomas <Thomas.Lendacky@....com>,
        herbert@...dor.apana.org.au,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-i2c@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] i2c: designware: Use PCI PSP driver for communication

On Thu, Feb 16, 2023 at 03:27:35PM -0600, Limonciello, Mario wrote:
> On 2/16/2023 15:16, Andy Shevchenko wrote:
> > On Thu, Feb 16, 2023 at 03:01:35PM -0600, Limonciello, Mario wrote:
> > > On 2/16/2023 14:59, Andy Shevchenko wrote:
> > > > On Thu, Feb 16, 2023 at 02:55:07PM -0600, Limonciello, Mario wrote:
> > > > > On 2/16/2023 08:56, Andy Shevchenko wrote:
> > > > > > On Thu, Feb 16, 2023 at 07:29:53AM -0600, Mario Limonciello wrote:
> > > > > > > On 2/16/23 07:27, Jarkko Nikula wrote:
> > > > > > > > On 2/10/23 00:38, Mario Limonciello wrote:

...

> > > > > > > > Would this look better if split? I.e.
> > > > > > > > 
> > > > > > > >        depends on CRYPTO_DEV_SP_PSP
> > > > > > > >        depends on !(I2C_DESIGNWARE_PLATFORM=y && CRYPTO_DEV_CCP_DD=m)
> > > > > > > Yes, thanks I'll change that for next version.
> > > > > > 
> > > > > > I'm wondering if this is homegrown implementation of 'imply' keyword?
> > > > > 
> > > > > Like this?
> > > > > 
> > > > > config I2C_DESIGNWARE_AMDPSP
> > > > >      depends on CRYPTO_DEV_SP_PSP
> > > > >      depends on CRYPTO_DEV_CCP_DD
> > > > > 
> > > > > config CRYPTO_DEV_CCP_DD
> > > > >      imply I2C_DESIGNWARE_PLATFORM
> > > > 
> > > > Looks okay, but I'm not familiar with this code. The documentation about
> > > > 'imply' can be found here:
> > > > 
> > > > https://www.kernel.org/doc/html/latest/kbuild/kconfig-language.html#menu-attributes
> > > 
> > > Yeah I found that, but this was my first time using imply, so I was hoping
> > > someone who has used it could validate I interpreted it correctly.
> > > 
> > > Following the example CRYPTO_DEV_CCP_DD would be FOO and
> > > I2C_DESIGNWARE_PLATFORM would be BAZ so I thought so.
> > 
> > 'imply' == weak 'select', it means that the target option may or may not be
> > selected. I.o.w. "optional" dependency.
> > 
> > Does CRYPTO_DEV_CCP_DD use I2C DesignWare code?
> > 
> > If I understand correctly the "depends on !(I2C_DESIGNWARE_PLATFORM=y &&
> > CRYPTO_DEV_CCP_DD=m)" you want to have IS_REACHABLE() in your code and actually
> > "imply CRYPTO_DEV_CCP_DD" in the I2C_DESIGNWARE_AMDPSP.
> 
> Allowing that combination and using IS_REACHABLE means that it's going to
> actually load earlier that expected, so I suppose it needs to be something
> like this then in the probe code for i2c-designware-amdpsp.c:
> 
> if (!IS_REACHABLE()
> 	return -EPROBE_DEFER;
> 
> Right?

Hmm... I'm not sure. IS_REACHABLE() should be done with a compilation
dependencies. What you put here is functional dependency, moreover since
you mentioned the boot / load ordering doesn't it mean that the architecture
of all of this is not good enough and requires some redesign?

Perhaps you need to use component framework actually?

-- 
With Best Regards,
Andy Shevchenko