MIPS: Add option to disable software I/O coherency.
Some MIPS controllers have hardware I/O coherency. This patch
detects those and turns off software coherency. A new kernel
command line option also allows the user to manually turn
software coherency on or off.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 2078915..f5943ab 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -33,6 +33,7 @@
#include <asm/war.h>
#include <asm/cacheflush.h> /* for run_uncached() */
#include <asm/traps.h>
+#include <asm/dma-coherence.h>
/*
* Special Variant of smp_call_function for use by cache functions:
@@ -1377,20 +1378,6 @@
}
}
-#if defined(CONFIG_DMA_NONCOHERENT)
-
-static int __cpuinitdata coherentio;
-
-static int __init setcoherentio(char *str)
-{
- coherentio = 1;
-
- return 0;
-}
-
-early_param("coherentio", setcoherentio);
-#endif
-
static void __cpuinit r4k_cache_error_setup(void)
{
extern char __weak except_vec2_generic;
@@ -1472,9 +1459,14 @@
build_clear_page();
build_copy_page();
-#if !defined(CONFIG_MIPS_CMP)
+
+ /*
+ * We want to run CMP kernels on core with and without coherent
+ * caches. Therefore, do not use CONFIG_MIPS_CMP to decide whether
+ * or not to flush caches.
+ */
local_r4k___flush_cache_all(NULL);
-#endif
+
coherency_setup();
board_cache_error_setup = r4k_cache_error_setup;
}
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index f9ef838..caf92ec 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -22,6 +22,26 @@
#include <dma-coherence.h>
+int coherentio = 0; /* User defined DMA coherency from command line. */
+EXPORT_SYMBOL_GPL(coherentio);
+int hw_coherentio = 0; /* Actual hardware supported DMA coherency setting. */
+
+static int __init setcoherentio(char *str)
+{
+ coherentio = 1;
+ pr_info("Hardware DMA cache coherency (command line)\n");
+ return 0;
+}
+early_param("coherentio", setcoherentio);
+
+static int __init setnocoherentio(char *str)
+{
+ coherentio = 0;
+ pr_info("Software DMA cache coherency (command line)\n");
+ return 0;
+}
+early_param("nocoherentio", setnocoherentio);
+
static inline struct page *dma_addr_to_page(struct device *dev,
dma_addr_t dma_addr)
{
@@ -115,7 +135,8 @@
if (!plat_device_is_coherent(dev)) {
dma_cache_wback_inv((unsigned long) ret, size);
- ret = UNCAC_ADDR(ret);
+ if (!hw_coherentio)
+ ret = UNCAC_ADDR(ret);
}
}
@@ -142,7 +163,7 @@
plat_unmap_dma_mem(dev, dma_handle, size, DMA_BIDIRECTIONAL);
- if (!plat_device_is_coherent(dev))
+ if (!plat_device_is_coherent(dev) && !hw_coherentio)
addr = CAC_ADDR(addr);
free_pages(addr, get_order(size));