Re: [bug report] rtc: ds1307: rx8130: honor Voltage Loss Flag when reading the time

[Dan Carpenter <dan.carpenter@oracle.com>]

On Wed, Feb 13, 2019 at 06:51:25PM +0100, Uwe Kleine-König wrote:
> Hello Dan,
> 
> On Wed, Feb 13, 2019 at 04:17:31PM +0300, Dan Carpenter wrote:
> > The patch 501f98266cad: "rtc: ds1307: rx8130: honor Voltage Loss Flag
> > when reading the time" from Jan 25, 2019, leads to the following
> > static checker warning:
> > 
> > 	drivers/rtc/rtc-ds1307.c:314 ds1307_set_time()
> > 	warn: this cast is a no-op
> > 
> > drivers/rtc/rtc-ds1307.c
> >     304 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
> >     305 				   sizeof(regs));
> >     306 	if (result) {
> >     307 		dev_err(dev, "%s error %d\n", "write", result);
> >     308 		return result;
> >     309 	}
> >     310 
> >     311 	if (ds1307->type == rx_8130) {
> >     312 		/* clear Voltage Loss Flag as data is available now */
> >     313 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
> > --> 314 				      ~(u8)RX8130_REG_FLAG_VLF);
> >                                                ^^^^^^^^^^^^^^^^^^^^^^^^
> > RX8130_REG_FLAG_VLF is 0x2.  The cast to u8 doesn't change anything
> > because it gets type promoted to int.  I don't know what was intended.
> 
> This reasoning looks right, yes. I don't remember why I added it.
> Probably because I intended to create the value 0xfd and not 0xfffffffd
> (aka -3).
> 
> Feel free to fix this in a patch blaming me.

If it's working as-is then I'm not going to be the one to break it...  :P

regards,
dan carpenter