Blackfin: support smaller uncached DMA chunks for memory constrained systems

When working with 8 meg systems, forcing a 1 meg DMA chunk heavily cuts
into the available resources.  So support smaller chunks to better cover
needs for these systems.

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index d703247caf2056f30a5c1e37f81aab6af4bafa11..8141b1e829270c4f0583b7b0fb479b4bf9ffd7ad 100644 (file)
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -896,6 +896,12 @@ config DMA_UNCACHED_2M
        bool "Enable 2M DMA region"
 config DMA_UNCACHED_1M
        bool "Enable 1M DMA region"
+config DMA_UNCACHED_512K
+       bool "Enable 512K DMA region"
+config DMA_UNCACHED_256K
+       bool "Enable 256K DMA region"
+config DMA_UNCACHED_128K
+       bool "Enable 128K DMA region"
 config DMA_UNCACHED_NONE
        bool "Disable DMA region"
 endchoice

diff --git a/arch/blackfin/include/asm/bfin-global.h b/arch/blackfin/include/asm/bfin-global.h
index 741c02112c063c59754c741cf7396feca9bb2d69..e6485c305ea6e53266412712216136ec126cac4b 100644 (file)
--- a/arch/blackfin/include/asm/bfin-global.h
+++ b/arch/blackfin/include/asm/bfin-global.h
@@ -20,6 +20,12 @@
 # define DMA_UNCACHED_REGION (2 * 1024 * 1024)
 #elif defined(CONFIG_DMA_UNCACHED_1M)
 # define DMA_UNCACHED_REGION (1024 * 1024)
+#elif defined(CONFIG_DMA_UNCACHED_512K)
+# define DMA_UNCACHED_REGION (512 * 1024)
+#elif defined(CONFIG_DMA_UNCACHED_256K)
+# define DMA_UNCACHED_REGION (256 * 1024)
+#elif defined(CONFIG_DMA_UNCACHED_128K)
+# define DMA_UNCACHED_REGION (128 * 1024)
 #else
 # define DMA_UNCACHED_REGION (0)
 #endif

diff --git a/arch/blackfin/kernel/cplb-nompu/cplbinit.c b/arch/blackfin/kernel/cplb-nompu/cplbinit.c
index fd9a2f31e686f63ceabe2354b401df5c919bb1f6..c9b0a4d53dc15f2b8cb5cb8453ecbc7e6b8cb43a 100644 (file)
--- 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) {
@@ -135,11 +145,7 @@ 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) {