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ARM: OMAP2: skip unnecessary TLDR write during non-autoreload for gptimer

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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 <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Paul Walmsley 2008-12-10 17:36:34 -08:00 committed by Tony Lindgren
parent a94b9e5a81
commit 64ce2907b1
1 changed files with 4 additions and 3 deletions
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7
arch/arm/plat-omap/dmtimer.c
View file

@ -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);
}