From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org,
Alessandro Zummo <a.zummo@towertech.it>
Subject: Re: [PATCH v2 2/2] rtc: hym8563: Read the valid flag directly instead of caching it
Date: Mon, 23 Dec 2019 11:18:49 +0100 [thread overview]
Message-ID: <20191223101849.GD1054858@piout.net> (raw)
In-Reply-To: <20191212153111.966923-2-paul.kocialkowski@bootlin.com>
On 12/12/2019 16:31:11+0100, Paul Kocialkowski wrote:
> The RTC has a valid bit in the seconds register that indicates whether
> power was lost since the pevious time set. This bit is currently read
> once at probe time, cached and updated with set_time.
>
> Howeever, caching the bit may prevent detecting power loss at runtime
> (which can happen if the RTC's supply is distinct from the the platform's).
>
> Writing the seconds register when setting time will clear the bit,
> so there should be no downside in reading the bit directly instead of
> caching it.
>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
> Changes since v1:
> - Removed hym8563 unused variables;
> - Checked buf[0] for VL flag instead of ret;
> - Reorded patches.
>
> drivers/rtc/rtc-hym8563.c | 19 +++++++------------
> 1 file changed, 7 insertions(+), 12 deletions(-)
Applied, thanks.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2019-12-23 10:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-12 15:31 [PATCH v2 1/2] rtc: hym8563: Return -EINVAL if the time is known to be invalid Paul Kocialkowski
2019-12-12 15:31 ` [PATCH v2 2/2] rtc: hym8563: Read the valid flag directly instead of caching it Paul Kocialkowski
2019-12-23 10:18 ` Alexandre Belloni [this message]
2019-12-23 10:18 ` [PATCH v2 1/2] rtc: hym8563: Return -EINVAL if the time is known to be invalid Alexandre Belloni
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