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

[Limonciello, Mario]

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:
>
> ...
>
> > > > > > > >        config I2C_DESIGNWARE_AMDPSP
> > > > > > > >          bool "AMD PSP I2C semaphore support"
> > > > > > > > -    depends on X86_MSR
> > > > > > > >          depends on ACPI
> > > > > > > >          depends on I2C_DESIGNWARE_PLATFORM
> > > > > > > > +    depends on CRYPTO_DEV_SP_PSP && !(I2C_DESIGNWARE_PLATFORM=y &&
> > > > > > > > CRYPTO_DEV_CCP_DD=m)
> > > > > > > >          help
> > > > > > >
> > > > > > > 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?