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

[Macpaul Lin <macpaul.lin@mediatek.com>]

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@collabora.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