From ca2afb6dbea74ee762ae5856af7045a57a65e9c8 Mon Sep 17 00:00:00 2001 From: Sudhakar Rajashekhara Date: Wed, 26 May 2010 14:41:49 -0700 Subject: davinci: mmc: pass number of SG segments as platform data On some platforms like DM355, the number of EDMA parameter slots available for EDMA_SLOT_ANY usage are few. In such cases, if MMC/SD uses 16 slots for each instance of MMC controller, then the number of slots available for other modules will be very few. By passing the number of EDMA slots to be used in MMC driver from platform data, EDMA slots available for other purposes can be controlled. Most of the platforms will not use this platform data variable. But on DM355, as the number of EDMA resources available is limited, the number of scatter- gather segments used inside the MMC driver can be 8 (passed as platform data) instead of 16. On DM355, when the number of scatter-gather segments was reduced to 8, I saw a performance difference of about 0.25-0.4 Mbytes/sec during write. Read performance variations were negligible. Signed-off-by: Sudhakar Rajashekhara Acked-by: Kevin Hilman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm/mach-davinci/include/mach/mmc.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm/mach-davinci/include/mach/mmc.h') diff --git a/arch/arm/mach-davinci/include/mach/mmc.h b/arch/arm/mach-davinci/include/mach/mmc.h index 5a85e24f367..d4f1e967506 100644 --- a/arch/arm/mach-davinci/include/mach/mmc.h +++ b/arch/arm/mach-davinci/include/mach/mmc.h @@ -22,6 +22,9 @@ struct davinci_mmc_config { /* Version of the MMC/SD controller */ u8 version; + + /* Number of sg segments */ + u8 nr_sg; }; void davinci_setup_mmc(int module, struct davinci_mmc_config *config); -- cgit v1.2.3-70-g09d2