linux-kernel - Re: [PATCH] misc: rtsx: Fix impossible condition

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Message-ID: <20191119075859.GC1858193@kroah.com>
Date:   Tue, 19 Nov 2019 08:58:59 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     rui_feng@...lsil.com.cn
Cc:     arnd@...db.de, dan.carpenter@...cle.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] misc: rtsx: Fix impossible condition

On Tue, Nov 19, 2019 at 03:33:45PM +0800, rui_feng@...lsil.com.cn wrote:
> From: Rui Feng <rui_feng@...lsil.com.cn>
> 
> A u8 can only go up to 255, condition n > 396 is
> impossible, so change u8 to u16.
> 
> Signed-off-by: Rui Feng <rui_feng@...lsil.com.cn>
> ---
>  drivers/misc/cardreader/rts5261.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/misc/cardreader/rts5261.c b/drivers/misc/cardreader/rts5261.c
> index 32dcec2..8dba0bf 100644
> --- a/drivers/misc/cardreader/rts5261.c
> +++ b/drivers/misc/cardreader/rts5261.c
> @@ -628,7 +628,8 @@ int rts5261_pci_switch_clock(struct rtsx_pcr *pcr, unsigned int card_clock,
>  		u8 ssc_depth, bool initial_mode, bool double_clk, bool vpclk)
>  {
>  	int err, clk;
> -	u8 n, clk_divider, mcu_cnt, div;
> +	u16 n;
> +	u8 clk_divider, mcu_cnt, div;
>  	static const u8 depth[] = {
>  		[RTSX_SSC_DEPTH_4M] = RTS5261_SSC_DEPTH_4M,
>  		[RTSX_SSC_DEPTH_2M] = RTS5261_SSC_DEPTH_2M,
> @@ -661,9 +662,9 @@ int rts5261_pci_switch_clock(struct rtsx_pcr *pcr, unsigned int card_clock,
>  		return 0;
>  
>  	if (pcr->ops->conv_clk_and_div_n)
> -		n = (u8)pcr->ops->conv_clk_and_div_n(clk, CLK_TO_DIV_N);
> +		n = (u16)pcr->ops->conv_clk_and_div_n(clk, CLK_TO_DIV_N);
>  	else
> -		n = (u8)(clk - 4);
> +		n = (u16)(clk - 4);

Why is the cast now needed?  Same for everywhere else.

thanks,

greg k-h