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

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Message-ID: <20161205220352.GB15449@emba-laptop>
Date:   Mon, 5 Dec 2016 23:03:52 +0100
From:   Emil Bartczak <emilbart@...il.com>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     a.zummo@...ertech.it, rtc-linux@...glegroups.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] rtc: mcp795: fix invalid month setting.

Hi,

On Mon, Dec 05, 2016 at 04:09:59PM +0100, Alexandre Belloni wrote:
> Hi,
> 
> On 05/12/2016 at 14:11:50 +0100, Emil Bartczak wrote :
> > The 10 month register was always set to value 0 in the RTC hardware.
> > Due to the bug month November or December became February.
> 
> All your patches are missing your SoB, see Developer's Certificate of
> Origin 1.1 in Documentation/SubmittingPatches
Ok, I will fix it in the next patchset. Sorry for that simple mistakes but 
I'm newbie in sending patches.

> 
> > ---
> >  drivers/rtc/rtc-mcp795.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/rtc/rtc-mcp795.c b/drivers/rtc/rtc-mcp795.c
> > index 4021fd0..266328b 100644
> > --- a/drivers/rtc/rtc-mcp795.c
> > +++ b/drivers/rtc/rtc-mcp795.c
> > @@ -29,7 +29,7 @@
> >  #define MCP795_EEWREN	0x06
> >  #define MCP795_SRREAD	0x05
> >  #define MCP795_SRWRITE	0x01
> > -#define MCP795_READ		0x13
> > +#define MCP795_READ	0x13
> 
> Unrelated change
Ok, I will remove it from patch.

> 
> >  #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.

> >  
> >  	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.
> 
> >  	tim->tm_year	= ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 100; /* Assume we are in 20xx */
> >  
> >  	dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
> > -- 
> > 2.7.4
> > 
> 
> -- 
> Alexandre Belloni, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com

Cheers,
Emil