Re: [PATCH] iio: gyro: mpu3050: fix chip ID reading

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 2 Mar 2019 21:48:30 +0300
Sergey Larin <cerg2010cerg2010@mail.ru> wrote:

> On Sat, Mar 02, 2019 at 06:08:24PM +0000, Jonathan Cameron wrote:
> > On Sat,  2 Mar 2019 19:54:55 +0300
> > Sergey Larin <cerg2010cerg2010@mail.ru> wrote:
> >   
> > > According to the datasheet, the last bit of CHIP_ID register controls
> > > I2C bus, and the first one is unused. Handle this correctly.
> > > 
> > > Signed-off-by: Sergey Larin <cerg2010cerg2010@mail.ru>  
> > Fix certainly seems to be correct, but seeing as we only support i2c for
> > this chip and that I assume the bottom bit is actually set (though
> > reserved), currently this is a tidy up rather than a fix.
> > 
> > Hence I'll take this the slow way rather than quickly as I would
> > a fix with actual effect.
> > 
> > Let me know if I've missed something!
> > 
> > Jonathan  
> 
> That's actually a fix for me. On my device, the bottom bit is set so driver
> reports an error. With this patch, driver probes OK, prints chip info to
> dmesg (die ID, revision, etc) and reports the data to sysfs, which looks
> correct.
Ah fair enough. Moved to the fixes-togreg branch with a note added
to the description that there are real parts out there where this matters.

Also added Linus' tag.

This will upstream sometime after rc1 in a few weeks time.

Thanks,

Jonathan
> 
> >   
> > > ---
> > >  drivers/iio/gyro/mpu3050-core.c | 8 +++++---
> > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
> > > index 77fac81a3adc..5ddebede31a6 100644
> > > --- a/drivers/iio/gyro/mpu3050-core.c
> > > +++ b/drivers/iio/gyro/mpu3050-core.c
> > > @@ -29,7 +29,8 @@
> > >  
> > >  #include "mpu3050.h"
> > >  
> > > -#define MPU3050_CHIP_ID		0x69
> > > +#define MPU3050_CHIP_ID		0x68
> > > +#define MPU3050_CHIP_ID_MASK	0x7E
> > >  
> > >  /*
> > >   * Register map: anything suffixed *_H is a big-endian high byte and always
> > > @@ -1176,8 +1177,9 @@ int mpu3050_common_probe(struct device *dev,
> > >  		goto err_power_down;
> > >  	}
> > >  
> > > -	if (val != MPU3050_CHIP_ID) {
> > > -		dev_err(dev, "unsupported chip id %02x\n", (u8)val);
> > > +	if ((val & MPU3050_CHIP_ID_MASK) != MPU3050_CHIP_ID) {
> > > +		dev_err(dev, "unsupported chip id %02x\n",
> > > +				(u8)(val & MPU3050_CHIP_ID_MASK));
> > >  		ret = -ENODEV;
> > >  		goto err_power_down;
> > >  	}  
> >