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Commit c45c0659 authored by Barry Song's avatar Barry Song Committed by Mike Frysinger
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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: default avatarBarry Song <barry.song@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
parent 5df326ac

arch/blackfin/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -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

arch/blackfin/include/asm/bfin-global.h

+6 −0
Original line number Diff line number Diff line
@@ -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

arch/blackfin/kernel/cplb-nompu/cplbinit.c

+13 −7
Original line number Diff line number Diff line
@@ -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) {