[EXT] Re: [PATCH v2] pmdomain: imx: Make IMX8M/IMX9 BLK_CTRL tristate

[Zhipeng Wang]

 > On 26-04-13, Zhipeng Wang wrote:
> > Convert IMX8M_BLK_CTRL and IMX9_BLK_CTRL from bool to tristate to
> > allow building as loadable modules.
>
> Out of curiosity, why do you want to have a PM driver to be buildable as
> module?
>
> Regards,
>   Marco
>
Hi Marco,

Thank you for your question.

The primary motivation is to support Google's GKI (Generic Kernel Image)
requirement for Android devices.

GKI separates the kernel into two parts:
1. A unified kernel image (GKI) that is common across all Android devices
2. Vendor-specific drivers that must be built as loadable modules

Under the GKI architecture, SoC-specific drivers like IMX8M/IMX9 BLK_CTRL
cannot be built into the core kernel image. Instead, they must be loadable
modules that vendors can ship separately. This allows:

- A single kernel binary to support multiple hardware platforms
- Vendors to update their drivers independently without rebuilding the entire kernel
- Better compliance with Android's kernel update and security policies

For i.MX8M/i.MX9 devices running Android with GKI kernels, the BLK_CTRL
drivers need to be loaded as modules during boot. Without tristate support,
these devices cannot properly initialize their power domains, making them
non-functional under GKI.

Best regards,
Zhipeng Wang
> > Add prompt strings to make these options visible and configurable in
> > menuconfig, keeping them enabled by default on appropriate platforms.
> >
> > Also remove the IMX_GPCV2_PM_DOMAINS dependency from
> IMX9_BLK_CTRL.
> > This dependency was incorrect from the beginning - i.MX93 uses a
> > different power domain architecture compared to i.MX8M series:
> >
> > - i.MX8M uses GPCv2 (General Power Controller v2) for power domain
> >   management, hence IMX8M_BLK_CTRL correctly depends on it.
> >
> > - i.MX93 uses BLK_CTRL directly without GPCv2. The hardware doesn't
> >   have GPCv2 at all.
> >
> > Signed-off-by: Zhipeng Wang <zhipeng.wang_1 at nxp.com>
> > ---
> >  drivers/pmdomain/imx/Kconfig | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pmdomain/imx/Kconfig
> > b/drivers/pmdomain/imx/Kconfig index 00203615c65e..9168d183b0c5
> 100644
> > --- a/drivers/pmdomain/imx/Kconfig
> > +++ b/drivers/pmdomain/imx/Kconfig
> > @@ -10,15 +10,18 @@ config IMX_GPCV2_PM_DOMAINS
> >       default y if SOC_IMX7D
> >
> >  config IMX8M_BLK_CTRL
> > -     bool
> > -     default SOC_IMX8M && IMX_GPCV2_PM_DOMAINS
> > +     tristate "i.MX8M BLK CTRL driver"
> > +     depends on SOC_IMX8M
> > +     depends on IMX_GPCV2_PM_DOMAINS
> >       depends on PM_GENERIC_DOMAINS
> >       depends on COMMON_CLK
> > +     default y
> >
> >  config IMX9_BLK_CTRL
> > -     bool
> > -     default SOC_IMX9 && IMX_GPCV2_PM_DOMAINS
> > +     tristate "i.MX93 BLK CTRL driver"
> > +     depends on SOC_IMX9
> >       depends on PM_GENERIC_DOMAINS
> > +     default y
> >
> >  config IMX_SCU_PD
> >       bool "IMX SCU Power Domain driver"
> > --
> > 2.34.1
> >
> >
> >
>
> --
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