Re: [PATCH v5 20/21] hwmon: (mr75203) add debugfs to read and write temperature coefficients

[Farber, Eliav]

On 9/8/2022 9:11 PM, Andy Shevchenko wrote:
> On Thu, Sep 08, 2022 at 03:24:48PM +0000, Eliav Farber wrote:
> > This change adds debugfs to read and write temperature sensor 
> > coefficients
> > - g, h, j and cal5.
> >
> > The coefficients can vary between product and product, so it can be very
> > useful to be able to modify them on the fly during the calibration
> > process.
> >
> > e.g.:
> >
> > cat /sys/kernel/debug/940f23d0000.pvt/ts_coeff_cal5
> > 4096
> >
> > echo 83000 > sys/kernel/debug/940f23d0000.pvt/ts_coeff_g
>
> ...
>
> > - Return j coefficient to use debugfs_create_file() instead of
> >   debugfs_create_u32() because j is signed.
>
> You can use
>
> DEFINE_DEBUGFS_ATTRIBUTE(ts_coeff_j, ts_coeff_j_get, ts_coeff_j_set, 
> "%lld\n");
>
> which still makes code compact. 


I tried your suggestion to use DEFINE_DEBUGFS_ATTRIBUTE but I can't set
j to be a negative value:

root@alpine:~# cat /sys/kernel/debug/940f23d0000.pvt/ts_coeff_j
0
root@alpine:~# echo 100 > /sys/kernel/debug/940f23d0000.pvt/ts_coeff_j
root@alpine:~# cat /sys/kernel/debug/940f23d0000.pvt/ts_coeff_j
100
root@alpine:~# echo -100 > /sys/kernel/debug/940f23d0000.pvt/ts_coeff_j
sh: write error: Invalid argument

This is the code I added:

static int ts_coeff_j_set(void *data, u64 val)
{
    struct pvt_device *pvt = data;

    pvt->ts_coeff.j = val;
    return 0;
}

static int ts_coeff_j_get(void *data, u64 *val)
{
    struct pvt_device *pvt = data;

    *val = pvt->ts_coeff.j;
    return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(ts_coeff_j_fops, ts_coeff_j_get,
             ts_coeff_j_set, "%lld\n");

static void devm_pvt_ts_dbgfs_remove(void *data)
{
    struct pvt_device *pvt = (struct pvt_device *)data;

    debugfs_remove_recursive(pvt->dbgfs_dir);
    pvt->dbgfs_dir = NULL;
}

static int pvt_ts_dbgfs_create(struct pvt_device *pvt, struct device *dev)
{
    ...
    debugfs_create_file("ts_coeff_j", 0644, pvt->dbgfs_dir, pvt,
                &ts_coeff_j_fops);
    ...

I'm using kernel 5.10.112.
Can you please see if I'm did anything wrong?

--
Thanks, Eliav