Re: [PATCH] hwmon: adc128d818: Fix value read from Device Tree

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Mar 26, 2019 at 12:01:57PM +0000, Carlos Menin wrote:
> On Tue, Mar 12, 2019 at 10:37:04AM -0700, Guenter Roeck wrote:
> > On Tue, Mar 12, 2019 at 05:10:48PM +0000, Carlos Menin wrote:
> > > On Tue, Mar 12, 2019 at 08:26:58AM -0700, Guenter Roeck wrote:
> > > > On Tue, Mar 12, 2019 at 01:14:39PM +0000, Carlos Menin wrote:
> > > > > Cells in DT are 32-bits in size. of_property_read_u8() does not work
> > > > > properly as it returns incorrect values in little-endian architectures.
> > > > > Fix it by using of_property_read_u32() instead.
> > > > > 
> > > > Are you saying that pretty much all callers of of_property_read_u8()
> > > > have this problem ? I would not rule that out, but it seems hard to
> > > > believe.
> > > > 
> > > > Guenter
> > > > 
> > > 
> > > Hi Guenter,
> > > 
> > > Yes, unless the DT entry specifies the cell size with '/bits/ 8' prefix.
> > > Not many drivers calls of_property_read_u8() function, almost all of
> > > them have this prefix in their binding examples, this being one of the
> > > exceptions. The fix could be a change in the documentation instead, if
> > > that is preferred.
> > > 
> > 
> > Yes, I would very much prefer that.
> > 
> > Guenter
> > 
> 
> Hi,
> 
> I sent a patch with the modification in the dt binding for this device,
> a couple weeks ago, but since e-mails from this address are rejected by
> vger.kernel.org, I used a differente e-mail address (one that I made
> sure that is accepted), if that is ok.
> 
Yes, it is available at https://patchwork.kernel.org/patch/10851189/

It is waiting for DT maintainer approval.

Guenter

> Best regards,
> Carlos.
> 
> 
> > > Carlos
> > > 
> > > > > Signed-off-by: Carlos Menin <carlos.menin@outlook.com>
> > > > > ---
> > > > >  drivers/hwmon/adc128d818.c | 4 ++--
> > > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/hwmon/adc128d818.c b/drivers/hwmon/adc128d818.c
> > > > > index ca794bf..b5eb3c0 100644
> > > > > --- a/drivers/hwmon/adc128d818.c
> > > > > +++ b/drivers/hwmon/adc128d818.c
> > > > > @@ -70,7 +70,7 @@ struct adc128_data {
> > > > >  	struct regulator *regulator;
> > > > >  	int vref;		/* Reference voltage in mV */
> > > > >  	struct mutex update_lock;
> > > > > -	u8 mode;		/* Operation mode */
> > > > > +	u32 mode;		/* Operation mode */
> > > > >  	bool valid;		/* true if following fields are valid */
> > > > >  	unsigned long last_updated;	/* In jiffies */
> > > > >  
> > > > > @@ -467,7 +467,7 @@ static int adc128_probe(struct i2c_client *client,
> > > > >  	}
> > > > >  
> > > > >  	/* Operation mode is optional. If unspecified, keep current mode */
> > > > > -	if (of_property_read_u8(dev->of_node, "ti,mode", &data->mode) == 0) {
> > > > > +	if (of_property_read_u32(dev->of_node, "ti,mode", &data->mode) == 0) {
> > > > >  		if (data->mode > 3) {
> > > > >  			dev_err(dev, "invalid operation mode %d\n",
> > > > >  				data->mode);
> > > > > -- 
> > > > > 2.7.4
> > > > >