Messages in this thread Patch in this message | | | From | Linus Walleij <> | Subject | [PATCH] clocksource: nomadik-mtu: Handle 32kHz clock | Date | Mon, 29 Jun 2020 00:01:53 +0200 |
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It happens on the U8420-sysclk Ux500 PRCMU firmware variant that the MTU clock is just 32768 Hz, and in this mode the minimum ticks is 5 rather than two.
I think this is simply so that there is enough time for the register write to propagate through the interconnect to the registers.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- drivers/clocksource/nomadik-mtu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/nomadik-mtu.c b/drivers/clocksource/nomadik-mtu.c index f49a631d8f58..1cf3304652d6 100644 --- a/drivers/clocksource/nomadik-mtu.c +++ b/drivers/clocksource/nomadik-mtu.c @@ -186,6 +186,7 @@ static int __init nmdk_timer_init(void __iomem *base, int irq, { unsigned long rate; int ret; + int min_ticks; mtu_base = base; @@ -194,7 +195,8 @@ static int __init nmdk_timer_init(void __iomem *base, int irq, /* * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz - * for ux500. + * for ux500, and in one specific Ux500 case 32768 Hz. + * * Use a divide-by-16 counter if the tick rate is more than 32MHz. * At 32 MHz, the timer (with 32 bit counter) can be programmed * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer @@ -230,7 +232,12 @@ static int __init nmdk_timer_init(void __iomem *base, int irq, pr_err("%s: request_irq() failed\n", "Nomadik Timer Tick"); nmdk_clkevt.cpumask = cpumask_of(0); nmdk_clkevt.irq = irq; - clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU); + if (rate < 100000) + min_ticks = 5; + else + min_ticks = 2; + clockevents_config_and_register(&nmdk_clkevt, rate, min_ticks, + 0xffffffffU); mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer; mtu_delay_timer.freq = rate; -- 2.26.2
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