RE: [PATCH wireless-next 2/2] rtlwifi: rtl8821ae: phy: fix an undefined bitwise shift behavior

[Ping-Ke Shih]

> -----Original Message-----
> From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Sent: Wednesday, November 22, 2023 9:02 PM
> To: Su Hui <suhui@xxxxxxxxxxxx>
> Cc: Ping-Ke Shih <pkshih@xxxxxxxxxxx>; kvalo@xxxxxxxxxx; nathan@xxxxxxxxxx; ndesaulniers@xxxxxxxxxx;
> trix@xxxxxxxxxx; lizetao1@xxxxxxxxxx; linville@xxxxxxxxxxxxx; Larry.Finger@xxxxxxxxxxxx;
> linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; llvm@xxxxxxxxxxxxxxx;
> kernel-janitors@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH wireless-next 2/2] rtlwifi: rtl8821ae: phy: fix an undefined bitwise shift behavior
> 
> Perhaps, a better way to silence the warning is to just change
> _rtl8821ae_phy_calculate_bit_shift() to not return 32 bits?  Do we
> really ever pass bitmask 0?  No idea...
> 

I think the bitmask should not 0, so just replace _rtl8821ae_phy_calculate_bit_shift()
by __ffs(bitmask). To be safer, callers can check bitmask is not 0 before calling. 

Ping-Ke