Re: [PATCH v3 02/19] hwmon: (mr75203) fix VM sensor allocation when "intel, vm-map" not defined

[Farber, Eliav]

On 8/31/2022 8:36 AM, Guenter Roeck wrote:
> On 8/30/22 12:21, Eliav Farber wrote:
> > Bug fix - in case "intel,vm-map" is missing in device-tree ,'num' is set
> > to 0, and no voltage channel infos are allocated.
> >
> > Signed-off-by: Eliav Farber <farbere@xxxxxxxxxx>
> > ---
> >   drivers/hwmon/mr75203.c | 28 ++++++++++++----------------
> >   1 file changed, 12 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
> > index 046523d47c29..0e29877a1a9c 100644
> > --- a/drivers/hwmon/mr75203.c
> > +++ b/drivers/hwmon/mr75203.c
> > @@ -580,8 +580,6 @@ static int mr75203_probe(struct platform_device 
> > *pdev)
> >       }
> >
> >       if (vm_num) {
> > -             u32 num = vm_num;
> > -
> >               ret = pvt_get_regmap(pdev, "vm", pvt);
> >               if (ret)
> >                       return ret;
> > @@ -594,30 +592,28 @@ static int mr75203_probe(struct platform_device 
> > *pdev)
> >               ret = device_property_read_u8_array(dev, "intel,vm-map",
> > pvt->vm_idx, vm_num);
> >               if (ret) {
> > -                     num = 0;
> > +                     /*
> > +                      * Incase intel,vm-map property is not defined, we
> > +                      * assume incremental channel numbers.
> > +                      */
> > +                     for (i = 0; i < vm_num; i++)
> > +                             pvt->vm_idx[i] = i;
> >               } else {
> >                       for (i = 0; i < vm_num; i++)
> >                               if (pvt->vm_idx[i] >= vm_num ||
> > -                                 pvt->vm_idx[i] == 0xff) {
> > -                                     num = i;
> > +                                 pvt->vm_idx[i] == 0xff)
> >                                       break;
>
> So all vm_idx values from 0x00 to 0xfe would be acceptable ?
> Does the chip really have that many registers (0x200 + 0x40 + 0x200 * 
> 0xfe) ?
> Is that documented somewhere ? 
According to the code vm_num is limited to 32 because the mask is
only 5 bits:

#define VM_NUM_MSK    GENMASK(20, 16)
#define VM_NUM_SFT    16
vm_num = (val & VM_NUM_MSK) >> VM_NUM_SFT;

In practice according to the data sheet I have:
0 <= VM instances <= 8

--
Regards, Eliav