linux-kernel - Re: [PATCH] misc: rtsx: Set setting

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Message-ID: <YoJ0I/XPoj1B/+mm@dev-arch.thelio-3990X>
Date:   Mon, 16 May 2022 08:56:19 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Tom Rix <trix@...hat.com>
Cc:     arnd@...db.de, gregkh@...uxfoundation.org, ndesaulniers@...gle.com,
        ricky_wu@...ltek.com, kai.heng.feng@...onical.com,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.

On Mon, May 16, 2022 at 09:00:47AM -0400, Tom Rix wrote:
> The clang build fails with
> rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>         } else if (efuse_valid == 0) {
>                    ^~~~~~~~~~~~~~~~
> 
> setting_reg2 is set in this block
>   if (efuse_valid == 2 || efuse_valid == 3) {
> ..
>   } else if (efuse_valid == 0) {
>     // default
> ..
>   }
> But efuse_valid can also have a value of 1.
> Change the 'else if' to 'else' to make the second block the default.
> 
> Fixes: b1c5f3085149 ("misc: rtsx: add rts5261 efuse function")
> Signed-off-by: Tom Rix <trix@...hat.com>

I am not sure if this fix is correct from a functional standpoint (i.e.
is treating efuse_valid == 1 the same as efuse_valid == 0 correct?) but
it is better than not handling this value altogether. For what it's
worth:

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

As a side note, it is unfortunate that this change made it into -next
when there was an outstanding report about this warning:

https://lore.kernel.org/202205100220.WyAyhKap-lkp@intel.com/

> ---
>  drivers/misc/cardreader/rts5261.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/cardreader/rts5261.c b/drivers/misc/cardreader/rts5261.c
> index 749cc5a46d13..f22634b14dc8 100644
> --- a/drivers/misc/cardreader/rts5261.c
> +++ b/drivers/misc/cardreader/rts5261.c
> @@ -403,7 +403,7 @@ static void rts5261_init_from_hw(struct rtsx_pcr *pcr)
>  			setting_reg1 = PCR_SETTING_REG4;
>  			setting_reg2 = PCR_SETTING_REG5;
>  		}
> -	} else if (efuse_valid == 0) {
> +	} else {
>  		// default
>  		setting_reg1 = PCR_SETTING_REG1;
>  		setting_reg2 = PCR_SETTING_REG2;
> -- 
> 2.27.0
> 

Cheers,
Nathan