linux-kernel - Re: [PATCH v2] rtc: s5m: fix to update ctrl register

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Message-id: <55DA5DCA.6080802@samsung.com>
Date:	Mon, 24 Aug 2015 08:56:58 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Joonyoung Shim <jy0922.shim@...sung.com>,
	rtc-linux@...glegroups.com
Cc:	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org, alexandre.belloni@...e-electrons.com,
	a.zummo@...ertech.it, sbkim73@...sung.com
Subject: Re: [PATCH v2] rtc: s5m: fix to update ctrl register

On 21.08.2015 18:43, Joonyoung Shim wrote:
> According to datasheet, the S2MPS13X and S2MPS14X should update write
> buffer via setting WUDR bit to high after ctrl register is written.
> 
> If not, ALARM interrupt of rtc-s5m doesn't happen first time when i use
> tools/testing/selftests/timers/rtctest.c test program and hour format is
> used to 12 hour mode in Odroid-XU3 board.
> 
> One more issue is the RTC doesn't keep time on Odroid-XU3 board when i
> turn on board after power off even if RTC battery is connected. It can
> be solved as setting WUDR & RUDR bits to high at the same time after
> RTC_CTRL register is written. It's same with condition of only writing
> ALARM registers, so this is for only S2MPS14 and we should set WUDR &
> A_UDR bits to high on S2MPS13.
> 
> I can't find any reasonable description about this like fix from
> datasheet, but can find similar codes from rtc driver source of
> hardkernel kernel and vender kernel.

s/vender/vendor/

> 
> Signed-off-by: Joonyoung Shim <jy0922.shim@...sung.com>
> Cc: <stable@...r.kernel.org> # v3.16
> ---
> Changelog for v2:
> - update commit description and code to fix time keeping problem
> - update the stable tag with the kernel version
> 
>  drivers/rtc/rtc-s5m.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-s5m.c b/drivers/rtc/rtc-s5m.c
> index 8c70d78..646bf45 100644
> --- a/drivers/rtc/rtc-s5m.c
> +++ b/drivers/rtc/rtc-s5m.c
> @@ -635,6 +635,16 @@ static int s5m8767_rtc_init_reg(struct s5m_rtc_info *info)
>  	case S2MPS13X:
>  		data[0] = (0 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
>  		ret = regmap_write(info->regmap, info->regs->ctrl, data[0]);
> +		if (ret < 0)
> +			break;
> +
> +		/*
> +		 * Should set WUDR & (RUDR or AUDR) bits to high after writing
> +		 * RTC_CTRL register like writing Alarm registers. We can't find
> +		 * the description from datasheet but vender code does that

s/vender/vendor/

> +		 * really.
> +		 */
> +		ret = s5m8767_rtc_set_alarm_reg(info);
>  		break;
>  
>  	default:
> 

Reviewed-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

Tested on S2MPS14 and S2MPS11:
Tested-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

Best regards,
Krzysztof


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