[PATCH] misc: rtsx: Fix impossible condition

[PATCH] misc: rtsx: Fix impossible condition

[rui_feng]

From: Rui Feng <rui_feng@realsil.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@realsil.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);
 	if ((clk <= 4) || (n > 396))
 		return -EINVAL;
 
@@ -676,7 +677,7 @@ int rts5261_pci_switch_clock(struct rtsx_pcr *pcr, unsigned int card_clock,
 		if (pcr->ops->conv_clk_and_div_n) {
 			int dbl_clk = pcr->ops->conv_clk_and_div_n(n,
 					DIV_N_TO_CLK) * 2;
-			n = (u8)pcr->ops->conv_clk_and_div_n(dbl_clk,
+			n = (u16)pcr->ops->conv_clk_and_div_n(dbl_clk,
 					CLK_TO_DIV_N);
 		} else {
 			n = (n + 4) * 2 - 4;
@@ -721,7 +722,7 @@ int rts5261_pci_switch_clock(struct rtsx_pcr *pcr, unsigned int card_clock,
 	rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SSC_CTL1, SSC_RSTB, 0);
 	rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SSC_CTL2,
 			SSC_DEPTH_MASK, ssc_depth);
-	rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SSC_DIV_N_0, 0xFF, n);
+	rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SSC_DIV_N_0, 0xFF, (u8)n);
 	rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SSC_CTL1, SSC_RSTB, SSC_RSTB);
 	if (vpclk) {
 		rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SD_VPCLK0_CTL,
-- 
1.9.1

Re: [PATCH] misc: rtsx: Fix impossible condition

[Greg KH]

On Tue, Nov 19, 2019 at 03:33:45PM +0800, rui_feng@realsil.com.cn wrote:
> From: Rui Feng <rui_feng@realsil.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@realsil.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