Re: [PATCH 1/4] rtc: mcp795: fix invalid month setting.

From: Alexandre Belloni
Date: Mon Dec 05 2016 - 17:16:06 EST


On 05/12/2016 at 23:03:52 +0100, Emil Bartczak wrote :
> >
> > > #define MCP795_WRITE 0x12
> > > #define MCP795_UNLOCK 0x14
> > > #define MCP795_IDWRITE 0x32
> > > @@ -39,6 +39,7 @@
> > >
> > > #define MCP795_ST_BIT 0x80
> > > #define MCP795_24_BIT 0x40
> > > +#define MCP795_LP_BIT 0x20
> > >
> > > static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
> > > {
> > > @@ -108,7 +109,8 @@ static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
> > > data[1] = (data[1] & 0x80) | ((tim->tm_min / 10) << 4) | (tim->tm_min % 10);
> > > data[2] = ((tim->tm_hour / 10) << 4) | (tim->tm_hour % 10);
> > > data[4] = ((tim->tm_mday / 10) << 4) | ((tim->tm_mday) % 10);
> > > - data[5] = (data[5] & 0x10) | (tim->tm_mon / 10) | (tim->tm_mon % 10);
> > > + data[5] = (data[5] & MCP795_LP_BIT) |
> >
> > You changed 0x10 in MCP795_LP_BIT which you defined as 0x20, is that
> > right?
> Yes, it should be 0x20 (checked in datasheet).
>
> >
> > This is also an unrelated change.
> >
> > > + ((tim->tm_mon / 10) << 4) | (tim->tm_mon % 10);
> What do you mean exactly?
> That above line of code was moved to the new line? Or that I added
> shift left operation (tim->tm_mon / 10) << 4)?
> Changing 0x10 to 0x20 and adding shift right operation fixes the problem.
>

I meant that I feel like changing 0x10 to 0x20 is a separate bugfix from
adding the shift. At least mention that in the commit message.

> > >
> > > if (tim->tm_year > 100)
> > > tim->tm_year -= 100;
> > > @@ -137,11 +139,11 @@ static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
> > > if (ret)
> > > return ret;
> > >
> > > - tim->tm_sec = ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
> > > - tim->tm_min = ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
> > > + tim->tm_sec = ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
> > > + tim->tm_min = ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
> > > tim->tm_hour = ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
> > > tim->tm_mday = ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
> > > - tim->tm_mon = ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
> > > + tim->tm_mon = ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
> >
> > All those whitespace changes are actually confusing. Please do them in a
> > separate patch or in your last patch.
> Ok, I will have a separate patch for them.

Maybe switching to bcd2bin/bin2bcd first is better as it touches all
those lines anyway and also solves the shift in mcp795_rtcc_read()


--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com