[AVR32] Fix incorrect invalidation of shared cachelines

Fix bug in dma_map_single(..., DMA_FROM_DEVICE) caused by incorrect
invalidation of shared cachelines at the beginning and/or end of
the specified buffer.  Those shared cachelines need to be flushed,
since they may hold valid data (which must not be discarded).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 24 insertions, 8 deletions

diff --git a/arch/avr32/mm/cache.c b/arch/avr32/mm/cache.c
index 450515b245a0..fb13f72e9a02 100644
--- a/arch/avr32/mm/cache.c
+++ b/arch/avr32/mm/cache.c
@@ -22,18 +22,34 @@
 
 void invalidate_dcache_region(void *start, size_t size)
 {
-        unsigned long v, begin, end, linesz;
+        unsigned long v, begin, end, linesz, mask;
+        int flush = 0;
 
         linesz = boot_cpu_data.dcache.linesz;
+        mask = linesz - 1;
+
+        /* when first and/or last cachelines are shared, flush them
+         * instead of invalidating ... never discard valid data!
+         */
+        begin = (unsigned long)start;
+        end = begin + size - 1;
+
+        if (begin & mask) {
+                flush_dcache_line(start);
+                begin += linesz;
+                flush = 1;
+        }
+        if ((end & mask) != mask) {
+                flush_dcache_line((void *)end);
+                end -= linesz;
+                flush = 1;
+        }
 
-        //printk("invalidate dcache: %p + %u\n", start, size);
-
-        /* You asked for it, you got it */
-        begin = (unsigned long)start & ~(linesz - 1);
-        end = ((unsigned long)start + size + linesz - 1) & ~(linesz - 1);
-
-        for (v = begin; v < end; v += linesz)
+        /* remaining cachelines only need invalidation */
+        for (v = begin; v <= end; v += linesz)
                 invalidate_dcache_line((void *)v);
+        if (flush)
+                flush_write_buffer();
 }
 
 void clean_dcache_region(void *start, size_t size)