diff options
Diffstat (limited to 'meta/recipes-kernel/linux/linux-omap2-git/beagleboard/02-gptimer_use_match_for_tick')
| -rw-r--r-- | meta/recipes-kernel/linux/linux-omap2-git/beagleboard/02-gptimer_use_match_for_tick | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/meta/recipes-kernel/linux/linux-omap2-git/beagleboard/02-gptimer_use_match_for_tick b/meta/recipes-kernel/linux/linux-omap2-git/beagleboard/02-gptimer_use_match_for_tick new file mode 100644 index 0000000000..6eb6c9b477 --- /dev/null +++ b/meta/recipes-kernel/linux/linux-omap2-git/beagleboard/02-gptimer_use_match_for_tick @@ -0,0 +1,97 @@ +OMAP2/3 system tick GPTIMER: use match interrupts rather than overflow interrupts + +From: Paul Walmsley <paul@pwsan.com> + +On some OMAP3 chips, GPTIMER1 will occasionally decline to interrupt +the MPU when a timer overflow event occurs. The timer stops running; +and TOCR is sometimes incremented; but the MPU apparently never receives +the interrupt. This patch was an experiment in using the GPTIMER +match interrupt to determine if it resolves the problem. +Unfortunately, it does not; the same problem occurs with match +interrupts; but this patch is preserved as the base for a +match+overflow interrupt workaround used in a following patch. +--- + + arch/arm/mach-omap2/timer-gp.c | 32 ++++++++++---------------------- + 1 files changed, 10 insertions(+), 22 deletions(-) + +diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c +index 557603f..51996ba 100644 +--- a/arch/arm/mach-omap2/timer-gp.c ++++ b/arch/arm/mach-omap2/timer-gp.c +@@ -36,6 +36,8 @@ + #include <asm/mach/time.h> + #include <asm/arch/dmtimer.h> + ++#define GPTIMER_MATCH_VAL 0xffff0000 ++ + static struct omap_dm_timer *gptimer; + static struct clock_event_device clockevent_gpt; + +@@ -44,7 +46,7 @@ static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id) + struct omap_dm_timer *gpt = (struct omap_dm_timer *)dev_id; + struct clock_event_device *evt = &clockevent_gpt; + +- omap_dm_timer_write_status(gpt, OMAP_TIMER_INT_OVERFLOW); ++ omap_dm_timer_write_status(gpt, OMAP_TIMER_INT_MATCH); + + evt->event_handler(evt); + return IRQ_HANDLED; +@@ -59,7 +61,7 @@ static struct irqaction omap2_gp_timer_irq = { + static int omap2_gp_timer_set_next_event(unsigned long cycles, + struct clock_event_device *evt) + { +- omap_dm_timer_set_load_start(gptimer, 0, 0xffffffff - cycles); ++ omap_dm_timer_set_load_start(gptimer, 0, GPTIMER_MATCH_VAL - cycles); + + return 0; + } +@@ -67,29 +69,12 @@ static int omap2_gp_timer_set_next_event(unsigned long cycles, + static void omap2_gp_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) + { +- u32 period; +- + omap_dm_timer_stop(gptimer); +- +- switch (mode) { +- case CLOCK_EVT_MODE_PERIODIC: +- period = clk_get_rate(omap_dm_timer_get_fclk(gptimer)) / HZ; +- period -= 1; +- +- omap_dm_timer_set_load_start(gptimer, 1, 0xffffffff - period); +- break; +- case CLOCK_EVT_MODE_ONESHOT: +- break; +- case CLOCK_EVT_MODE_UNUSED: +- case CLOCK_EVT_MODE_SHUTDOWN: +- case CLOCK_EVT_MODE_RESUME: +- break; +- } + } + + static struct clock_event_device clockevent_gpt = { + .name = "gp timer", +- .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, ++ .features = CLOCK_EVT_FEAT_ONESHOT, + .shift = 32, + .set_next_event = omap2_gp_timer_set_next_event, + .set_mode = omap2_gp_timer_set_mode, +@@ -111,12 +96,15 @@ static void __init omap2_gp_clockevent_init(void) + + omap2_gp_timer_irq.dev_id = (void *)gptimer; + setup_irq(omap_dm_timer_get_irq(gptimer), &omap2_gp_timer_irq); +- omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW); ++ omap_dm_timer_stop(gptimer); ++ /* omap_dm_timer_set_load(gptimer, 0, 0);*/ ++ omap_dm_timer_set_match(gptimer, 1, GPTIMER_MATCH_VAL); ++ omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_MATCH); + + clockevent_gpt.mult = div_sc(tick_rate, NSEC_PER_SEC, + clockevent_gpt.shift); + clockevent_gpt.max_delta_ns = +- clockevent_delta2ns(0xffffffff, &clockevent_gpt); ++ clockevent_delta2ns(GPTIMER_MATCH_VAL, &clockevent_gpt); + clockevent_gpt.min_delta_ns = + clockevent_delta2ns(1, &clockevent_gpt); + |