On Thu, Jun 19, 2014 at 2:41 PM, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote: > On 06/19/2014 10:39 AM, Amit Daniel Kachhap wrote: >> >> This patch register the exynos mct clocksource as the current timer >> as it has constant clock rate. This will generate correct udelay for the >> exynos platform and avoid using unnecessary calibrated jiffies. This >> change >> has been tested on exynos5420 based board and udelay is very close to >> expected. >> >> Signed-off-by: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx> >> --- >> Changes in V2: >> * Added #defines for ARM and ARM64 as pointed by Doug Anderson. >> >> Patches from David Riley confirmed that udelay is broken in exynos5420. >> Link to those patches are, >> 1) https://patchwork.kernel.org/patch/4344911/ >> 2) https://patchwork.kernel.org/patch/4344881/ >> >> drivers/clocksource/exynos_mct.c | 15 +++++++++++++++ >> 1 file changed, 15 insertions(+) >> >> diff --git a/drivers/clocksource/exynos_mct.c >> b/drivers/clocksource/exynos_mct.c >> index f71d55f..02927e2 100644 >> --- a/drivers/clocksource/exynos_mct.c >> +++ b/drivers/clocksource/exynos_mct.c >> @@ -195,10 +195,25 @@ static u64 notrace exynos4_read_sched_clock(void) >> return exynos4_frc_read(&mct_frc); >> } >> >> +static struct delay_timer exynos4_delay_timer; >> + >> +static unsigned long exynos4_read_current_timer(void) >> +{ >> +#ifdef ARM >> + return __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_L); >> +#else /* ARM64, etc */ >> + return exynos4_frc_read(&mct_frc); >> +#endif >> +} >> + > > > There isn't another solution than that ? macros definitions in C file are > avoided as much as possible. I also didn't want to use macros but used as a last option. you want me to put more comments here? Or something like below is also possible for checking the size of (unsigned long) in runtime. unsigned long x; unsigned int size = (char *)(&x + 1) - (char *)(&x); if (size == 4) return __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_L); else return exynos4_frc_read(&mct_frc); But this involves extra computation which should not be used for time critical functions. Any suggestion? > > >> static void __init exynos4_clocksource_init(void) >> { >> exynos4_mct_frc_start(); >> >> + exynos4_delay_timer.read_current_timer = >> &exynos4_read_current_timer; > > > &exynos4_read_current_timer ? Any issue in the naming? > > >> + exynos4_delay_timer.freq = clk_rate; >> + register_current_timer_delay(&exynos4_delay_timer); >> + >> if (clocksource_register_hz(&mct_frc, clk_rate)) >> panic("%s: can't register clocksource\n", mct_frc.name); >> >> > > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog > > -- > To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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