Re: [RESEND RFC PATCH v3] rtc: Fix the AltCentury value on AMD/Hygon platform

[Jinke Fan]

On 2019/10/20 6:04, Alexandre Belloni wrote:
> On 15/10/2019 16:08:27+0800, Jinke Fan wrote:
>>      save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
>> -    CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
>> +
>> +#ifdef CONFIG_X86
>> +    if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
>> +        boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
>> +            CMOS_WRITE((save_freq_select & (~RTC_DV0)), RTC_FREQ_SELECT);
> 
> This should probably use ~RTC_DIV_RESET2.

Yes, ~RTC_DIV_RESET2 can actually achieve the same effect, because of
bit5-bit6 is defined as reserved.

>> +    else
>> +            CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), 
>> RTC_FREQ_SELECT);
>> +#else
>> +    CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
>> +#endif
> 
> Also, later you have:
> 
> CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
> 
> This may write bit4 again which would make mc146818_get_time fail so you
> probably want to update save_freq_select.

Yes, thanks for reminding me.

-- 
Best Regards,
Jinke Fan.