On Thu, Jun 19, 2014 at 4:00 PM, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote: > On 06/19/2014 12:21 PM, amit daniel kachhap wrote: >> >> 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? > > > AFAIU, Doug may change the exynos4_frc_read to be 32 bits. So may not need > those macros as 'exynos4_frc_read' could be used instead. right, its better to wait till those patches are out. > > Doug may confirm this. > > >>>> 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? > > > No problem with the naming. As Tomasz pointed also, you are passing '&' for > the function pointer. yes my mistake. > > >>>> + 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 > > > > -- > <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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