Re: [PATCH v2 2/2] eeprom: at24: Add support for address-width property

[Sakari Ailus]

On Tue, Jun 26, 2018 at 07:11:54AM +0000, Chiang, AlanX wrote:
> Hi Sakari,
> 
> > -----Original Message-----
> > From: Sakari Ailus [mailto:sakari.ailus@xxxxxxxxxxxxxxx]
> > Sent: Tuesday, June 26, 2018 2:48 PM
> > To: Chiang, AlanX <alanx.chiang@xxxxxxxxx>
> > Cc: linux-i2c@xxxxxxxxxxxxxxx; Yeh, Andy <andy.yeh@xxxxxxxxx>;
> > Shevchenko, Andriy <andriy.shevchenko@xxxxxxxxx>; Mani, Rajmohan
> > <rajmohan.mani@xxxxxxxxx>; andy.shevchenko@xxxxxxxxx; brgl@xxxxxxxx;
> > robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; arnd@xxxxxxxx;
> > gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH v2 2/2] eeprom: at24: Add support for address-width
> > property
> > 
> > Hi Alan,
> > 
> > On Tue, Jun 26, 2018 at 02:22:08PM +0800, alanx.chiang@xxxxxxxxx wrote:
> > > From: "alanx.chiang" <alanx.chiang@xxxxxxxxx>
> > >
> > > Provide a flexible way to determine the addressing bits of eeprom.
> > > Pass the addressing bits to driver through address-width property.
> > >
> > > Signed-off-by: Alan Chiang <alanx.chiang@xxxxxxxxx>
> > > Signed-off-by: Andy Yeh <andy.yeh@xxxxxxxxx>
> > >
> > > ---
> > > since v1
> > > -- Add a warn message for 8-bit addressing.
> > >
> > > ---
> > >  drivers/misc/eeprom/at24.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> > > index 0c125f2..231afcd 100644
> > > --- a/drivers/misc/eeprom/at24.c
> > > +++ b/drivers/misc/eeprom/at24.c
> > > @@ -478,6 +478,22 @@ static void at24_properties_to_pdata(struct device
> > *dev,
> > >  	if (device_property_present(dev, "no-read-rollover"))
> > >  		chip->flags |= AT24_FLAG_NO_RDROL;
> > >
> > > +	err = device_property_read_u32(dev, "address-width", &val);
> > > +	if (!err) {
> > > +		switch (val) {
> > > +		case 8:
> > > +			chip->flags &= ~AT24_FLAG_ADDR16;
> > > +			dev_warn(dev, "address-width is 8, clear the ADD16
> > bit\n");
> > 
> > Even though the default is 8 address bits, I don't see a need to issue a
> > warning if the address-width property sets that to 8 explicitly. I.e. only warn
> > if the flag was set.
> > 
> 
> Do you mean I have to add a statement for checking if the bit has been set before?
> For example:
> 
> If (chip->flags & AT24_FLAG_ADDR16)
> 	dev_warn(dev, "address-width is 8, clear the ADD16 bit\n");
> 
> If it is, I would like to modify it as below:
> 
> case 8:
> 	If (chip->flags & AT24_FLAG_ADDR16) {
> 		chip->flags &= ~AT24_FLAG_ADDR16;
> 		dev_warn(dev, "address-width is 8, clear the ADDR16 bit\n");
> 	}
> 	break;

Seems good to me.

-- 
Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx