linux-kernel - Re: [PATCH v1 2/3] rtc: mt6359: Add RTC hardware range and add support for start-year

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Message-ID: <72ce817e-63de-40a7-b7e9-a5b44b67e207@collabora.com>
Date: Tue, 24 Sep 2024 11:30:25 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Macpaul Lin <macpaul.lin@...iatek.com>, lee@...nel.org,
 ZhanZhan.ge@...iatek.com
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 matthias.bgg@...il.com, eddie.huang@...iatek.com, sean.wang@...iatek.com,
 alexandre.belloni@...tlin.com, sen.chu@...iatek.com,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 linux-rtc@...r.kernel.org, kernel@...labora.com, yong.mao@...iatek.com
Subject: Re: [PATCH v1 2/3] rtc: mt6359: Add RTC hardware range and add
 support for start-year

Il 24/09/24 09:05, Macpaul Lin ha scritto:
> 
> On 9/24/24 12:08, Macpaul Lin wrote:
>>
>> On 9/23/24 18:00, AngeloGioacchino Del Regno wrote:
>>> Add the RTC hardware range parameters to enable the possibility
>>> of using the `start-year` devicetree property which, if present,
>>> will set the start_secs parameter by overriding the defaults
>>> that this driver is setting;
>>>
>>> To keep compatibility with (hence have the same date/time reading
>>> as) the old behavior, set:
>>>   - range_min to 1900-01-01 00:00:00
>>>   - range_max to 2027-12-31 23:59:59 (HW year max range is 0-127)
>>>   - start_secs defaulting to 1968-01-02 00:00:00
>>>
>>> Please note that the oddness of starting from January 2nd is not
>>> a hardware quirk and it's done only to get the same date/time
>>> reading as an RTC which time was set before this commit.
>>>
>>> Also remove the RTC_MIN_YEAR_OFFSET addition and subtraction in
>>> callbacks set_time() and read_time() respectively, as now this
>>> is already done by the API.
>>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>> ---
>>>   drivers/rtc/rtc-mt6397.c | 13 ++++---------
>>>   1 file changed, 4 insertions(+), 9 deletions(-)
>>
>> [snip]
>>
>> Thanks for helping add new patch fix for RTC.
>>
>>> @@ -302,6 +293,10 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>>>       device_init_wakeup(&pdev->dev, 1);
>>>       rtc->rtc_dev->ops = &mtk_rtc_ops;
>>> +    rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
>>> +    rtc->rtc_dev->range_max = mktime64(2027, 12, 31, 23, 59, 59);
>>> +    rtc->rtc_dev->start_secs = mktime64(1968, 1, 2, 0, 0, 0);
>>> +    rtc->rtc_dev->set_start_time = true;
>>>       return devm_rtc_register_device(rtc->rtc_dev);
>>>   }
>>
>> Dear @Zhanhan, Please help to leave comment if you think there is something need 
>> to be clarify. For example, I've found some relate origin defines
>> in "include/linux/mfd/mt6397/rtc.h"
>> #define RTC_MIN_YEAR    1968
>> #define RTC_BASE_YEAR    1900
>> #define RTC_NUM_YEAR    128
>> #define RTC_MIN_YEAR_OFFSET    (RTC_MIN_YEAR - RTC_BASE_YEAR)
>>
>> Should MediaTek remove RTC_MIN_YEAR and RTC_BASE_YEAR in next patch?
>> And since there may not exist any smartphone/tablet/TV using mt6397
>> RTC earlier than 2010? Is it possible to change
>> RTC_TIMESTAMP_BEGIN_1900 to RTC_TIMESTAMP_BEGIN_2000 without breaking
>> compatibility for these devices?
>>
>> Thanks
>> Macpaul Lin
>>
> 
> After discussing these change with ZhanZhan, MediaTek think use 
> RTC_TIMESTAMP_BEGIN_1900 and the other changes are okay.
> 
> Reviewed-by: Macpaul Lin <macpaul.lin@...iatek.com>
> Reviewed-by: ZhanZhan Ge <zhanzhan.ge@...iatek.com>
> 

Thank you Macpaul, ZhanZhan :-)

Cheers,
Angelo