Re: [PATCH v4 1/3] net: dsa: microchip: implement KSZ87xx Module 3 low-loss cable errata

[Fidelio LAWSON <lawson.fidelio@gmail.com>]

On 4/17/26 16:35, Marek Vasut wrote:
> On 4/17/26 2:44 PM, Fidelio Lawson wrote:
> 
> [...]
> 
>> @@ -1271,6 +1287,29 @@ int ksz8_w_phy(struct ksz_device *dev, u16 phy, 
>> u16 reg, u16 val)
>>           if (ret)
>>               return ret;
>>           break;
>> +    case PHY_REG_KSZ87XX_SHORT_CABLE:
>> +        if (!ksz_is_ksz87xx(dev))
>> +            return -EOPNOTSUPP;
>> +        ret = ksz87xx_apply_low_loss_preset(dev, !!val);
>> +        if (ret)
>> +            return ret;
>> +        break;
>> +    case PHY_REG_KSZ87XX_LPF_BW:
>> +        if (!ksz_is_ksz87xx(dev))
>> +            return -EOPNOTSUPP;
>> +        ret = ksz8_ind_write8(dev, TABLE_LINK_MD, 
>> KSZ87XX_REG_PHY_LPF, (u8)val);
>> +        if (ret)
>> +            return ret;
>> +        dev->lpf_bw = val;
>> +        break;
>> +    case PHY_REG_KSZ87XX_EQ_INIT:
>> +        if (!ksz_is_ksz87xx(dev))
>> +            return -EOPNOTSUPP;
>> +        ret = ksz8_ind_write8(dev, TABLE_LINK_MD, KSZ87XX_REG_DSP_EQ, 
>> (u8)val);
> Do these values need some check, so they would be in the correct 
> range(s) / in the correct bitfields before being written into those 
> registers ?

Yes, I can add validation to ensure that only the documented bitfields 
are accepted before writing the registers, (bits [7:6] for the LPF 
bandwidth and bits [5:0] for the DSP EQ initial value).