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 d703247..8141b1e 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -896,6 +896,12 @@
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 741c021..e6485c3 100644
--- 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 fd9a2f3..c9b0a4d 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_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 @@
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) {