Re: [PATCH 1/5] wifi: rtl8xxxu: Add central frequency offset tracking

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

On 21/10/2022 08:47, Ping-Ke Shih wrote:
> 
> 
>> -----Original Message-----
>> From: Bitterblue Smith <rtl8821cerfe2@gmail.com>
>> Sent: Monday, October 17, 2022 1:27 AM
[...]
>> +
>> +	val32 &= ~0x007ff800;
>> +	val32 |= (crystal_cap | (crystal_cap << 6)) << 11;
>> +	rtl8xxxu_write32(priv, REG_AFE_XTAL_CTRL, val32);
> 
> This could be clear:
> 
> #define XTAL1 GENMASK(22, 17)
> #define XTAL0 GENMASK(16, 11)
> 
> val32 &= ~(XTAL1 | XTAL2)
> val32 |= FIELD_PREP(XTAL1, crystal_cap) |
>          FIELD_PREP(XTAL0, crystal_cap);
> 

Ah, so that's what FIELD_PREP does.

>> +			if (priv->cfo_tracking.packet_count == 0xffffffff)
>> +				priv->cfo_tracking.packet_count = 0;
>> +			else
>> +				priv->cfo_tracking.packet_count++;
> 
> 'packet_count' is u32, so 0xffffffff + 1 will become 0. Then, just
> 
>    priv->cfo_tracking.packet_count++;
> 

I thought so, but I'm not *that* familiar with the C standard,
so I left it how I found it in one of the Realtek drivers.

>> +
>> +	if (crystal_cap > 0x3f)
>> +		crystal_cap = 0x3f;
>> +	else if (crystal_cap < 0)
>> +		crystal_cap = 0;
> 
> crystal_cap = clamp(crystal_cap, 0, 0x3f);
> 

Right, that's better.

Thanks for the reviews. I'll implement your suggestions.