From: Paul Walmsley Date: Wed, 26 Nov 2008 18:48:12 +0000 (-0800) Subject: OMAP2/3 GPTIMER: skip unnecessary TLDR write during non-autoreload X-Git-Tag: v2.6.28-omap1~102 X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?p=linux-2.6-omap-h63xx.git;a=commitdiff_plain;h=b83574c10b73546fad0e4d57c2d8066b80e1a480 OMAP2/3 GPTIMER: skip unnecessary TLDR write during non-autoreload 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 6111d99dacc..5708fd818e8 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); }