On Thu, Jun 19, 2014 at 4:47 AM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > Amit, > > Thanks for posting! > > On Wed, Jun 18, 2014 at 4:31 AM, Amit Daniel Kachhap > <amit.daniel@xxxxxxxxxxx> 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 >> have been tested on exynos5420 based board. >> >> Signed-off-by: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx> >> --- >> >> 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 | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c >> index 8d64200..57cb3dc 100644 >> --- a/drivers/clocksource/exynos_mct.c >> +++ b/drivers/clocksource/exynos_mct.c >> @@ -198,10 +198,21 @@ 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) >> +{ >> + return exynos4_frc_read(&mct_frc); > > This is terribly inefficient to read all 64-bits and then cast back to > a 32-bit value. Replace with: Yes agree. This unsigned long strangely behaves as 32 bits for arm32 and 64 bits for arm64. So I think it better is to do something like this, +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 +} + I will post V2 version like above and see what the maintainer says. > > return __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_L); > > >> +} >> + >> static void __init exynos4_clocksource_init(void) >> { >> exynos4_mct_frc_start(0, 0); > > Please rebase atop (1d80415 clocksource: exynos_mct: Don't reset the > counter during boot and resume), which is in linuxnext among other > places. OK will re base my patch on top of this. > >> >> + exynos4_delay_timer.read_current_timer = &exynos4_read_current_timer; >> + 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); > > It does seem to work for me though. :) thanks, > -- > 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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