[SPARC]: Mark as emulating cmpxchg, add appropriate depends for DRM.

The DRM code depends on an atomic version of cmpxchg(), which is not
available on sparc32. Since other platforms besides sparc32 have this
issue a KCONFIG option is added for it.

Signed-off-by: Martin Habets <errandir_news@mph.eclipse.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index bd992c0..fbcc00c 100644 (file)
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -178,6 +178,13 @@ config ARCH_HAS_ILOG2_U64
        bool
        default n
 
+config EMULATED_CMPXCHG
+       bool
+       default y
+       help
+         Sparc32 does not have a CAS instruction like sparc64. cmpxchg()
+         is emulated, and therefore it is not completely atomic.
+
 config SUN_PM
        bool
        default y

diff --git a/drivers/char/drm/Kconfig b/drivers/char/drm/Kconfig
index ef833a1..0b7ffa5 100644 (file)
--- a/drivers/char/drm/Kconfig
+++ b/drivers/char/drm/Kconfig
@@ -6,7 +6,7 @@
 #
 config DRM
        tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
-       depends on (AGP || AGP=n) && PCI
+       depends on (AGP || AGP=n) && PCI && !EMULATED_CMPXCHG
        help
          Kernel-level support for the Direct Rendering Infrastructure (DRI)
          introduced in XFree86 4.0. If you say Y here, you need to select