MIPS: Sanitise coherentio semantics

The coherentio variable has previously been used as a boolean value,
indicating whether the user specified that coherent I/O should be
enabled or disabled. It failed to take into account the case where the
user does not specify any preference, in which case it makes sense that
we should default to coherent I/O if the hardware supports it
(hw_coherentio is non-zero).

Introduce an enum to clarify the 3 different values of coherentio & use
it throughout the code, modifying plat_device_is_coherent() &
r4k_cache_init() to take into account the default case.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/14347/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 755259c54976..8b86c6168239 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -25,13 +25,14 @@
 #include <dma-coherence.h>
 
 #ifdef CONFIG_DMA_MAYBE_COHERENT
-int coherentio = 0;	/* User defined DMA coherency from command line. */
+/* User defined DMA coherency from command line. */
+enum coherent_io_user_state coherentio = IO_COHERENCE_DEFAULT;
 EXPORT_SYMBOL_GPL(coherentio);
 int hw_coherentio = 0;	/* Actual hardware supported DMA coherency setting. */
 
 static int __init setcoherentio(char *str)
 {
-	coherentio = 1;
+	coherentio = IO_COHERENCE_ENABLED;
 	pr_info("Hardware DMA cache coherency (command line)\n");
 	return 0;
 }
@@ -39,7 +40,7 @@ early_param("coherentio", setcoherentio);
 
 static int __init setnocoherentio(char *str)
 {
-	coherentio = 0;
+	coherentio = IO_COHERENCE_DISABLED;
 	pr_info("Software DMA cache coherency (command line)\n");
 	return 0;
 }