From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Li Yang <leoyang.li@nxp.com>
Cc: Biwen Li <biwen.li@nxp.com>,
a.zummo@towertech.it, linux-rtc@vger.kernel.org,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [v2] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w
Date: Fri, 16 Aug 2019 18:28:25 +0200 [thread overview]
Message-ID: <20190816162825.GE3545@piout.net> (raw)
In-Reply-To: <CADRPPNRkqbWzGEvUJyi0Qff3oS6biO0v7BTrK1Jiz9AMnOYF=Q@mail.gmail.com>
On 16/08/2019 10:50:49-0500, Li Yang wrote:
> On Fri, Aug 16, 2019 at 3:05 AM Alexandre Belloni
> <alexandre.belloni@bootlin.com> wrote:
> >
> > On 16/08/2019 10:46:36+0800, Biwen Li wrote:
> > > Issue:
> > > - # hwclock -w
> > > hwclock: RTC_SET_TIME: Invalid argument
> > >
> > > Why:
> > > - Relative patch: https://lkml.org/lkml/2019/4/3/55 , this patch
> > > will always check for unwritable registers, it will compare reg
> > > with max_register in regmap_writeable.
> > >
> > > - In drivers/rtc/rtc-pcf85363.c, CTRL_STOP_EN is 0x2e, but DT_100THS
> > > is 0, max_regiter is 0x2f, then reg will be equal to 0x30,
> > > '0x30 < 0x2f' is false,so regmap_writeable will return false.
> > >
> > > - Root cause: the buf[] was written to a wrong place in the file
> > > drivers/rtc/rtc-pcf85363.c
> > >
> >
> > This is not true, the RTC wraps the register accesses properly and this
>
> This performance hack probably deserve some explanation in the code comment. :)
>
> > is probably something that should be handled by regmap_writable.
>
> The address wrapping is specific to this RTC chip. Is it also
> commonly used by other I2C devices? I'm not sure if regmap_writable
> should handle the wrapping case if it is too special.
>
Most of the i2c RTCs do address wrapping which is sometimes the only way
to properly set the time.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2019-08-16 16:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 2:46 [v2] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w Biwen Li
2019-08-16 8:04 ` Alexandre Belloni
2019-08-16 15:50 ` Li Yang
2019-08-16 16:28 ` Alexandre Belloni [this message]
2019-08-16 19:40 ` Li Yang
2019-08-20 18:22 ` Mark Brown
2019-08-20 18:33 ` Li Yang
2019-08-21 11:21 ` Mark Brown
2019-08-21 11:24 ` Alexandre Belloni
2019-08-21 11:30 ` Mark Brown
2019-08-21 11:38 ` Alexandre Belloni
2019-08-21 11:47 ` Mark Brown
2019-08-21 6:20 ` Nandor Han
2019-08-26 4:29 ` [EXT] " Biwen Li
2019-08-26 9:17 ` Nandor Han
2019-08-26 9:49 ` Biwen Li
2019-08-26 10:06 ` Alexandre Belloni
2019-08-26 10:40 ` Biwen Li
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