Re: [PATCH 3/3] drm/panthor: Fix undefined panthor_device_suspend/resume symbol issue

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 04 Mar 2024, Boris Brezillon <boris.brezillon@collabora.com> wrote:
> panthor_device_resume/suspend() are only compiled when CONFIG_PM is
> enabled but panthro_drv.c doesn't use the pm_ptr() macro to conditionally
> discard resume/suspend assignments, which causes undefined symbol
> errors at link time when !PM.
>
> We could fix that by using pm_ptr(), but supporting the !PM case makes
> little sense (the whole point of these embedded GPUs is to be low power,
> so proper PM is a basic requirement in that case). So let's just enforce
> the presence of CONFIG_PM with a Kconfig dependency instead.
>
> If someone needs to relax this dependency, it can be done in a follow-up.

This breaks the config for me:

  SYNC    include/config/auto.conf.cmd
  GEN     Makefile
drivers/iommu/Kconfig:14:error: recursive dependency detected!
drivers/iommu/Kconfig:14:	symbol IOMMU_SUPPORT is selected by DRM_PANTHOR
drivers/gpu/drm/panthor/Kconfig:3:	symbol DRM_PANTHOR depends on PM
kernel/power/Kconfig:183:	symbol PM is selected by PM_SLEEP
kernel/power/Kconfig:117:	symbol PM_SLEEP depends on HIBERNATE_CALLBACKS
kernel/power/Kconfig:35:	symbol HIBERNATE_CALLBACKS is selected by XEN_SAVE_RESTORE
arch/x86/xen/Kconfig:67:	symbol XEN_SAVE_RESTORE depends on XEN
arch/x86/xen/Kconfig:6:	symbol XEN depends on PARAVIRT
arch/x86/Kconfig:781:	symbol PARAVIRT is selected by HYPERV
drivers/hv/Kconfig:5:	symbol HYPERV depends on X86_LOCAL_APIC
arch/x86/Kconfig:1106:	symbol X86_LOCAL_APIC depends on X86_UP_APIC
arch/x86/Kconfig:1081:	symbol X86_UP_APIC prompt is visible depending on PCI_MSI
drivers/pci/Kconfig:39:	symbol PCI_MSI is selected by AMD_IOMMU
drivers/iommu/amd/Kconfig:3:	symbol AMD_IOMMU depends on IOMMU_SUPPORT
For a resolution refer to Documentation/kbuild/kconfig-language.rst
subsection "Kconfig recursive dependency limitations"


BR,
Jani.


>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202403031944.EOimQ8WK-lkp@intel.com/
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> ---
>  drivers/gpu/drm/panthor/Kconfig          | 1 +
>  drivers/gpu/drm/panthor/panthor_device.c | 2 --
>  2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/Kconfig b/drivers/gpu/drm/panthor/Kconfig
> index 55b40ad07f3b..fdce7c1b2310 100644
> --- a/drivers/gpu/drm/panthor/Kconfig
> +++ b/drivers/gpu/drm/panthor/Kconfig
> @@ -6,6 +6,7 @@ config DRM_PANTHOR
>  	depends on ARM || ARM64 || COMPILE_TEST
>  	depends on !GENERIC_ATOMIC64  # for IOMMU_IO_PGTABLE_LPAE
>  	depends on MMU
> +	depends on PM
>  	select DEVFREQ_GOV_SIMPLE_ONDEMAND
>  	select DRM_EXEC
>  	select DRM_GEM_SHMEM_HELPER
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 68e467ee458a..efea29143a54 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -403,7 +403,6 @@ int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *
>  	return 0;
>  }
>  
> -#ifdef CONFIG_PM
>  int panthor_device_resume(struct device *dev)
>  {
>  	struct panthor_device *ptdev = dev_get_drvdata(dev);
> @@ -548,4 +547,3 @@ int panthor_device_suspend(struct device *dev)
>  	mutex_unlock(&ptdev->pm.mmio_lock);
>  	return ret;
>  }
> -#endif

-- 
Jani Nikula, Intel