linux-kernel - Re: [PATCH v3 09/19] hwmon: (mr75203) add VM active channel support

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Date:   Fri, 2 Sep 2022 15:04:55 +0300
From:   "Farber, Eliav" <farbere@...zon.com>
To:     Andy Shevchenko <andriy.shevchenko@...el.com>
CC:     <jdelvare@...e.com>, <linux@...ck-us.net>, <robh+dt@...nel.org>,
        <p.zabel@...gutronix.de>, <rtanwar@...linear.com>,
        <linux-hwmon@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <talel@...zon.com>,
        <hhhawa@...zon.com>, <jonnyc@...zon.com>, <hanochu@...zon.com>,
        <ronenk@...zon.com>, <itamark@...zon.com>, <shellykz@...zon.com>,
        <shorer@...zon.com>, <amitlavi@...zon.com>, <almogbs@...zon.com>,
        <dkl@...zon.com>, "Farber, Eliav" <farbere@...zon.com>
Subject: Re: [PATCH v3 09/19] hwmon: (mr75203) add VM active channel support

On 8/31/2022 2:48 PM, Andy Shevchenko wrote:
> On Tue, Aug 30, 2022 at 07:22:02PM +0000, Eliav Farber wrote:
>> Add active channel support per voltage monitor.
>> The number of active channels is read from the device-tree.
>> When absent in device-tree, all channels are assumed to be used.
>>
>> This shall be useful to expose sysfs only for inputs that are connected
>> to a voltage source.
>>
>> Setting number of active channels to 0, means that entire VM sensor is
>> not used.
>
> ...
>
>> +struct voltage_device {
>> +     u32 vm_map;     /* Map channel number to VM index */
>> +     u32 ch_map;     /* Map channel number to channel index */
>> +};
>> +
>> +struct voltage_channels {
>> +     u32 total;      /* Total number of channels in all VMs */
>> +     u8 max;         /* Maximum number of channels among all VMs */
>> +};
>
> Why not convert them to kernel doc?
>
Fixed in v4.


>> +     ret = device_property_read_u8_array(dev, 
>> "moortec,vm-active-channels",
>> +                                         vm_active_ch, vm_num);
>> +     if (ret) {
>> +             /*
>> +              * Incase vm-active-channels property is not defined,
>> +              * we assume each VM sensor has all of its channels
>> +              * active.
>> +              */
>> +             for (i = 0; i < vm_num; i++)
>> +                     vm_active_ch[i] = ch_num;
>
> NIH memset().

Fixed in v4.


>> +             pvt->vm_channels.max = ch_num;
>> +             pvt->vm_channels.total = ch_num * vm_num;
>> +     } else {
>> +             for (i = 0; i < vm_num; i++) {
>> +                     if (vm_active_ch[i] > ch_num) {
>> +                             dev_err(dev, "invalid active channels: 
>> %u\n",
>> +                                     vm_active_ch[i]);
>> +                             return -EINVAL;
>> +                     }
>> +
>> +                     pvt->vm_channels.total += vm_active_ch[i];
>> +
>> +                     if (vm_active_ch[i] > pvt->vm_channels.max)
>> +                             pvt->vm_channels.max = vm_active_ch[i];
>> +             }
>> +     }
>
> ...
>
>> +     k = 0;
>> +     for (i = 0; i < vm_num; i++)
>> +             for (j = 0; j < vm_active_ch[i]; j++) {
>> +                     pvt->vd[k].vm_map = vm_idx[i];
>> +                     pvt->vd[k].ch_map = j;
>
>> +                     k++;
>
> How is it different from moving this outside the inner loop as
>
>        k += vm_active_ch[i];
>
> ?

k is used inside the inner loop, so increasing it outside the inner loop
will result in a different incorrect setting of vm_map and ch_map.

>> +             }
>
> Missed outer {}.

Fixed in v4.


--
Regards, Eliav