1 files changed, 19 insertions, 12 deletions

diff --git a/arch/blackfin/kernel/cplb-nompu/cplbinit.c b/arch/blackfin/kernel/cplb-nompu/cplbinit.c
index fd9a2f31e686..282a7919821b 100644
--- a/arch/blackfin/kernel/cplb-nompu/cplbinit.c
+++ b/arch/blackfin/kernel/cplb-nompu/cplbinit.c
@@ -89,15 +89,25 @@ void __init generate_cplb_tables_cpu(unsigned int cpu)
 
 void __init generate_cplb_tables_all(void)
 {
+        unsigned long uncached_end;
         int i_d, i_i;
 
         i_d = 0;
         /* Normal RAM, including MTD FS.  */
 #ifdef CONFIG_MTD_UCLINUX
-        dcplb_bounds[i_d].eaddr = memory_mtd_start + mtd_size;
+        uncached_end = memory_mtd_start + mtd_size;
 #else
-        dcplb_bounds[i_d].eaddr = memory_end;
+        uncached_end = memory_end;
 #endif
+        /*
+         * if DMA uncached is less than 1MB, mark the 1MB chunk as uncached
+         * so that we don't have to use 4kB pages and cause CPLB thrashing
+         */
+        if ((DMA_UNCACHED_REGION >= 1 * 1024 * 1024) || !DMA_UNCACHED_REGION ||
+            ((_ramend - uncached_end) >= 1 * 1024 * 1024))
+                dcplb_bounds[i_d].eaddr = uncached_end;
+        else
+                dcplb_bounds[i_d].eaddr = uncached_end & ~(1 * 1024 * 1024);
         dcplb_bounds[i_d++].data = SDRAM_DGENERIC;
         /* DMA uncached region.  */
         if (DMA_UNCACHED_REGION) {
@@ -135,18 +145,15 @@ void __init generate_cplb_tables_all(void)
 
         i_i = 0;
         /* Normal RAM, including MTD FS.  */
-#ifdef CONFIG_MTD_UCLINUX
-        icplb_bounds[i_i].eaddr = memory_mtd_start + mtd_size;
-#else
-        icplb_bounds[i_i].eaddr = memory_end;
-#endif
+        icplb_bounds[i_i].eaddr = uncached_end;
         icplb_bounds[i_i++].data = SDRAM_IGENERIC;
-        /* DMA uncached region.  */
-        if (DMA_UNCACHED_REGION) {
-                icplb_bounds[i_i].eaddr = _ramend;
-                icplb_bounds[i_i++].data = 0;
-        }
         if (_ramend != physical_mem_end) {
+                /* DMA uncached region.  */
+                if (DMA_UNCACHED_REGION) {
+                        /* Normally this hole is caught by the async below.  */
+                        icplb_bounds[i_i].eaddr = _ramend;
+                        icplb_bounds[i_i++].data = 0;
+                }
                 /* Reserved memory.  */
                 icplb_bounds[i_i].eaddr = physical_mem_end;
                 icplb_bounds[i_i++].data = (reserved_mem_icache_on ?