Re: [PATCH 3/5] hwmon: (socfpga) Add hardware monitoring support on SoCFPGA platforms

[Dinh Nguyen]

On 4/19/2023 6:46 AM, Andy Shevchenko wrote:
> On Tue, Apr 18, 2023 at 12:29:40PM -0500, Dinh Nguyen wrote:
> > On 4/17/2023 4:51 PM, Guenter Roeck wrote:
> > > On 4/17/23 13:55, Dinh Nguyen wrote:
> ...
>
> > > ... and this contradict each other. If bit 31 indicates an error,
> > > this can not be a signed 32-bit value.
> > You're right! I've re-read the spec and should have the the code look for
> > the specific error values:
> >
> > 0x80000000 - inactive
> > 0x80000001 - old value
> > 0x80000002 - invalid channel
> > 0x80000003 -  corrupted.
> No, they are not hex. Probably you need to define an error space with it, but
> at least just use signed _decimal_ values.
>
> Instead of BIT(31) this should go as
>
> #define ..._ERR_BASE   INT_MIN // or equivalent if the type is not int
> #define ..._ERR_MAX ... // or whatever name is better
>
> Then in your code
>
> 	if (value >= _ERR_MAX)
> 		return 0;
>
> 	err = _ERR_MAX - value;
> 	switch (err) {
> 		...
> 	}
>
> P.S. I asked during internal review if the values are bit fielded when errors.
> AFAIU that time they are, now it seems different.

Can I ask what's wrong with this simple implementation?

static int socfpga_hwmon_err_to_errno(struct socfpga_hwmon_priv *priv)
{
        int value = priv->temperature.value;

        switch (value) {
        case ETEMP_NOT_PRESENT:
                return -ENOENT;
        case ETEMP_CORRUPT:
        case ETEMP_NOT_INITIALIZED:
                return -ENODATA;
        case ETEMP_BUSY:
                return -EBUSY;
        case ETEMP_INACTIVE:
        case ETEMP_TIMEOUT:
        case ETEMP_TOO_OLD:
                return -EAGAIN;
        default:
                /* No error */
                return 0;
        }
}

Dinh