From: Jinke Fan <fanjinke@hygon.cn>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: "a.zummo@towertech.it" <a.zummo@towertech.it>,
Wen Pu <puwen@hygon.cn>,
"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
"kim.phillips@amd.com" <kim.phillips@amd.com>,
"linux-rtc@vger.kernel.org" <linux-rtc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND RFC PATCH v3] rtc: Fix the AltCentury value on AMD/Hygon platform
Date: Mon, 21 Oct 2019 03:08:50 +0000 [thread overview]
Message-ID: <26fee8c9-695d-7703-bac9-5582ab560ae5@hygon.cn> (raw)
In-Reply-To: <20191019220456.GP3125@piout.net>
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.
prev parent reply other threads:[~2019-10-21 3:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-15 8:08 [RESEND RFC PATCH v3] rtc: Fix the AltCentury value on AMD/Hygon platform Jinke Fan
2019-10-15 8:27 ` Alexandre Belloni
2019-10-15 10:08 ` Jinke Fan
2019-10-19 22:04 ` Alexandre Belloni
2019-10-21 3:08 ` Jinke Fan [this message]
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