From: Paul Walmsley Date: Thu, 11 Dec 2008 01:36:34 +0000 (-0800) Subject: ARM: OMAP2: skip unnecessary TLDR write during non-autoreload for gptimer X-Git-Tag: v2.6.29-rc1~559^2~14^2~6 X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?p=linux-2.6-omap-h63xx.git;a=commitdiff_plain;h=64ce2907b1966593d3b4ce5396adb17d7348637d ARM: OMAP2: skip unnecessary TLDR write during non-autoreload for gptimer The GPTIMER TLDR register does not need to be written if the GPTIMER is not in autoreload mode. This is the usual case for dynamic tick-enabled kernels. Simulation data indicate that skipping the read that occurs as part of the write should save at least 300-320 ns for each GPTIMER1 timer reprogram. (This assumes L4-Wakeup is at 19MHz and GPTIMER write posting is enabled.) Skipping the write itself probably won't have much impact since it should be posted on the OCP interconnect. Tested on 2430SDP and 3430SDP. Signed-off-by: Paul Walmsley Cc: Richard Woodruff Acked-by: Kevin Hilman Signed-off-by: Tony Lindgren --- diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c index 595e3d5092c..e4f0ce04ba9 100644 --- a/arch/arm/plat-omap/dmtimer.c +++ b/arch/arm/plat-omap/dmtimer.c @@ -549,14 +549,15 @@ void omap_dm_timer_set_load_start(struct omap_dm_timer *timer, int autoreload, u32 l; l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG); - if (autoreload) + if (autoreload) { l |= OMAP_TIMER_CTRL_AR; - else + omap_dm_timer_write_reg(timer, OMAP_TIMER_LOAD_REG, load); + } else { l &= ~OMAP_TIMER_CTRL_AR; + } l |= OMAP_TIMER_CTRL_ST; omap_dm_timer_write_reg(timer, OMAP_TIMER_COUNTER_REG, load); - omap_dm_timer_write_reg(timer, OMAP_TIMER_LOAD_REG, load); omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l); }