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

Farber, Eliav
2022-08-31T05:50:26Z

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@amazon.com>
>> ---
>>   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