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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>
This commit is contained in:
Barry Song 2009-12-02 09:13:36 +00:00 committed by Mike Frysinger
parent 5df326aca4
commit c45c06596e
3 changed files with 25 additions and 7 deletions
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6
arch/blackfin/Kconfig
View File

@ -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

6
arch/blackfin/include/asm/bfin-global.h
View File

@ -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

20
arch/blackfin/kernel/cplb-nompu/cplbinit.c
View File

@ -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) {