[PATCH] powerpc: Restrict ARCH_HIBERNATION_POSSIBLE to supported configurations

[Vishal Chourasia]

This patch modifies the ARCH_HIBERNATION_POSSIBLE option to ensure that it
correctly depends on these PowerPC configurations being enabled. As a result,
it prevents the HOTPLUG_CPU from being selected when the required dependencies
are not satisfied.

This change aligns the dependency tree with the expected hardware support for
CPU hot-plugging under PowerPC architectures, ensuring that the kernel
configuration steps do not lead to inconsistent states.

Signed-off-by: Vishal Chourasia <vishalc at linux.ibm.com>
---
During the configuration process with 'make randconfig' followed by
'make olddefconfig', we observed a warning indicating an unmet direct
dependency for the HOTPLUG_CPU option. The dependency in question relates to
various PowerPC configurations (PPC_PSERIES, PPC_PMAC, PPC_POWERNV,
FSL_SOC_BOOKE) which were not enabled, yet the HOTPLUG_CPU was being
erroneously selected due to an implicit assumption by the PM_SLEEP_SMP option.
This misalignment in dependencies could potentially lead to inconsistent kernel
configuration states, especially when considering the necessary hardware
support for CPU hot-plugging on PowerPC platforms. The patch aims to correct
this by ensuring that ARCH_HIBERNATION_POSSIBLE is contingent upon the
appropriate PowerPC configurations being active.

steps to reproduce (before applying the patch):

Run 'make pseries_le_defconfig'
Run 'make menuconfig'
Enable hibernation [ Kernel options -> Hibernation (aka 'suspend to disk') ] 
Disable [ Platform support -> IBM PowerNV (Non-Virtualized) platform support ]
Disable [ Platform support -> IBM pSeries & new (POWER5-based) iSeries ]
Enable SMP [ Processor support -> Symmetric multi-processing support ]
Save the config
Run 'make olddefconfig'

 arch/powerpc/Kconfig | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6f105ee4f3cf..bf99ff9869f6 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -380,8 +380,9 @@ config DEFAULT_UIMAGE
 	  Used to allow a board to specify it wants a uImage built by default
 
 config ARCH_HIBERNATION_POSSIBLE
-	bool
-	default y
+	def_bool y
+	depends on PPC_PSERIES || \
+		PPC_PMAC || PPC_POWERNV || FSL_SOC_BOOKE
 
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
-- 
2.41.0