Re: [rtc-linux] Re: invalid default values in RTC chip

[Jüri Reitel]

David Brownell wrote:
> On Thursday 23 October 2008, Jüri Reitel wrote:
>   
> > I included patch that just removes the RTC time registers check, when i 
> > compiled the module and booted up with invalid values in RTC then system 
> > automatically set system time and RTC time to 1.1.2000 (this is nice 
> > because i dont have to use date and hwclock manually)
> >     
>
> I wouldn't rely on the initial time setting being valid;
> it's not guaranteed by specs for all the chips, as I recall.
>
>  
>   
> > i checked the rtc_valid_tm function and saw that it also checks for the 
> > year value among others but in ds1307_read_alarm (now this function is 
> > renamed to ds1337_read_alarm) year is set to -1 with some other fields 
> > so rtc_valid_tm function can not be used in ds1337_read_alarm function.
> >     
>
> Right.  I forget what alarm issues I was thinking of, but
> that wasn't it ... other code in the RTC framework handles
> morphing that time into a valid date.
>
>
>   
> > This patch removes rtc date time values check in probe function
> >     
>  
> Thanks.  This looks OK ... got a Signed-off-By for us?
>
>
>   
> > --- a/drivers/rtc/rtc-ds1307.c
> > +++ b/drivers/rtc/rtc-ds1307.c
> > @@ -298,7 +298,7 @@ static int ds1307_set_time(struct device *dev, 
> > struct rtc_time *t)
> >      return 0;
> >  }
> >  
> > -static int ds1307_read_alarm(struct device *dev, struct rtc_wkalrm *t)
> > +static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
> >  {
> >      struct i2c_client       *client = to_i2c_client(dev);
> >      struct ds1307        *ds1307 = i2c_get_clientdata(client);
> > @@ -353,7 +353,7 @@ static int ds1307_read_alarm(struct device *dev, 
> > struct rtc_wkalrm *t)
> >      return 0;
> >  }
> >  
> > -static int ds1307_set_alarm(struct device *dev, struct rtc_wkalrm *t)
> > +static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
> >  {
> >      struct i2c_client       *client = to_i2c_client(dev);
> >      struct ds1307        *ds1307 = i2c_get_clientdata(client);
> > @@ -475,8 +475,8 @@ static int ds1307_ioctl(struct device *dev, unsigned 
> > int cmd, unsigned long arg)
> >  static const struct rtc_class_ops ds13xx_rtc_ops = {
> >      .read_time    = ds1307_get_time,
> >      .set_time    = ds1307_set_time,
> > -    .read_alarm    = ds1307_read_alarm,
> > -    .set_alarm    = ds1307_set_alarm,
> > +    .read_alarm    = ds1337_read_alarm,
> > +    .set_alarm    = ds1337_set_alarm,
> >      .ioctl        = ds1307_ioctl,
> >  };
> >  
> > @@ -707,22 +707,6 @@ read_rtc:
> >          break;
> >      }
> >  
> > -    tmp = ds1307->regs[DS1307_REG_SECS];
> > -    tmp = bcd2bin(tmp & 0x7f);
> > -    if (tmp > 60)
> > -        goto exit_bad;
> > -    tmp = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
> > -    if (tmp > 60)
> > -        goto exit_bad;
> > -
> > -    tmp = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
> > -    if (tmp == 0 || tmp > 31)
> > -        goto exit_bad;
> > -
> > -    tmp = bcd2bin(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
> > -    if (tmp == 0 || tmp > 12)
> > -        goto exit_bad;
> > -
> >      tmp = ds1307->regs[DS1307_REG_HOUR];
> >      switch (ds1307->type) {
> >      case ds_1340:
> > @@ -779,13 +763,6 @@ read_rtc:
> >  
> >      return 0;
> >  
> > -exit_bad:
> > -    dev_dbg(&client->dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
> > -            "bogus register",
> > -            ds1307->regs[0], ds1307->regs[1],
> > -            ds1307->regs[2], ds1307->regs[3],
> > -            ds1307->regs[4], ds1307->regs[5],
> > -            ds1307->regs[6]);
> >  exit_irq:
> >      if (ds1307->rtc)
> >          rtc_device_unregister(ds1307->rtc);
> >
> >     
>
>
>
>
>   
Thank you pointing to not rely on random values on RTC chip, i had luck 
when reinserted battery from/to RTC in random initial values (that gave 
me 1.1.2000).

Signed-off-by: Jüri Reitel <juri.reitel@xxxxxxxxxxxxx>

JR

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/