zhaoxin inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I54V04 CVE: NA ---------------------------------------------------------------- When the RTC divider is changed from reset to an operating time base, the first update cycle should be 500ms later. But on some Zhaoxin SOCs, this first update cycle is one second later. So set RTC time on these Zhaoxin SOCs will causing 500ms delay. Skip setup RTC divider on these SOCs in mc146818_set_time to fix it. Signed-off-by: LeoLiu-oc <LeoLiu-oc@zhaoxin.com> ---  drivers/rtc/rtc-mc146818-lib.c | 26 +++++++++++++++++++++++---  1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index 2f1772a358ca..1a866ebbbe62 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -7,6 +7,23 @@  #include <linux/acpi.h>  #endif +#ifdef CONFIG_X86 +static inline bool follow_mc146818_divider_reset(void) +{ +    if ((boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR || +        boot_cpu_data.x86_vendor == X86_VENDOR_ZHAOXIN) && +        (boot_cpu_data.x86 <= 7 && boot_cpu_data.x86_model <= 59)) { +        return false; +    } +    return true; +} +#else +static inline bool follow_mc146818_divider_reset(void) +{ +    return true; +} +#endif +  /*   * Returns true if a clock update is in progress   */ @@ -170,8 +187,10 @@ int mc146818_set_time(struct rtc_time *time)      save_control = CMOS_READ(RTC_CONTROL);      CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); -    save_freq_select = CMOS_READ(RTC_FREQ_SELECT); -    CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); +    if (follow_mc146818_divider_reset()) { +        save_freq_select = CMOS_READ(RTC_FREQ_SELECT); +        CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); +    }  #ifdef CONFIG_MACH_DECSTATION      CMOS_WRITE(real_yrs, RTC_DEC_YEAR); @@ -189,7 +208,8 @@ int mc146818_set_time(struct rtc_time *time)  #endif      CMOS_WRITE(save_control, RTC_CONTROL); -    CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); +    if (follow_mc146818_divider_reset()) +        CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);      spin_unlock_irqrestore(&rtc_lock, flags); -- 2.20.1