Re: [PATCH] drm/xe/vsec: enforce CONFIG_INTEL_VSEC dependency

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Dec 17, 2024 at 08:18:44AM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When INTEL_VSEC is in a loadable module, XE cannot be built-in any more:
> 
> x86_64-linux-ld: vmlinux.o: in function `xe_vsec_init':
> (.text+0x19861bf): undefined reference to `intel_vsec_register'
> 
> This could be enforced using a 'depends on INTEL_VSEC || !INTEL_VSEC'
> style dependency to allow building with VSEC completely disabled.
> My impression here is that this was not actually intended, and that
> continuing to support that combination would lead to more build bugs.
> 
> Instead, make it a hard dependency as all other INTEL_VSEC users are,
> and remove the inline stub alternative. This leads to a dependency
> on CONFIG_X86_PLATFORM_DEVICES, so the 'select' has to be removed
> to avoid a circular dependency.
> 

I really don't want us to hard lock this X86 dependency here.
What if we add a new DRM_XE_DGFX_PMT_SUPPORT and that
depends on INTEL_VSEC ?

and our if statement changes to
if (IS_ENABLED(DRM_XE_DGFX_PMT_SUPPORT)

We could even leave this enabled by default, but at least
it is an easy path to someone willing to run experiments
without depending on X86 I believe...

Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>

> Fixes: 0c45e76fcc62 ("drm/xe/vsec: Support BMG devices")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/xe/Kconfig | 2 +-
>  include/linux/intel_vsec.h | 7 -------
>  2 files changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> index 6c5b665d9384..217b51468497 100644
> --- a/drivers/gpu/drm/xe/Kconfig
> +++ b/drivers/gpu/drm/xe/Kconfig
> @@ -2,6 +2,7 @@
>  config DRM_XE
>  	tristate "Intel Xe Graphics"
>  	depends on DRM && PCI && MMU && (m || (y && KUNIT=y))
> +	depends on INTEL_VSEC
>  	select INTERVAL_TREE
>  	# we need shmfs for the swappable backing store, and in particular
>  	# the shmem_readpage() which depends upon tmpfs
> @@ -28,7 +29,6 @@ config DRM_XE
>  	select INPUT if ACPI
>  	select ACPI_VIDEO if X86 && ACPI
>  	select ACPI_BUTTON if ACPI
> -	select X86_PLATFORM_DEVICES if X86 && ACPI
>  	select ACPI_WMI if X86 && ACPI
>  	select SYNC_FILE
>  	select IOSF_MBI
> diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
> index b94beab64610..f2d55e686476 100644
> --- a/include/linux/intel_vsec.h
> +++ b/include/linux/intel_vsec.h
> @@ -138,13 +138,6 @@ static inline struct intel_vsec_device *auxdev_to_ivdev(struct auxiliary_device
>  	return container_of(auxdev, struct intel_vsec_device, auxdev);
>  }
>  
> -#if IS_ENABLED(CONFIG_INTEL_VSEC)
>  void intel_vsec_register(struct pci_dev *pdev,
>  			 struct intel_vsec_platform_info *info);
> -#else
> -static inline void intel_vsec_register(struct pci_dev *pdev,
> -				       struct intel_vsec_platform_info *info)
> -{
> -}
> -#endif
>  #endif
> -- 
> 2.39.5
>