diff mbox series

ASoC: sgtl5000: avoid division by zero if lo_vag is zero

Message ID 20180906104152.17977-1-colin.king@canonical.com (mailing list archive)
State New, archived
Headers show
Series ASoC: sgtl5000: avoid division by zero if lo_vag is zero | expand

Commit Message

Colin King Sept. 6, 2018, 10:41 a.m. UTC 
From: Colin Ian King <colin.king@canonical.com>

In the case where lo_vag <= SGTL5000_LINE_OUT_GND_BASE, lo_vag
is set to zero and later vol_quot is computed by dividing by
lo_vag causing a division by zero error.  Fix this by avoiding
a zero division and set vol_quot to zero in this specific case
so that the lowest setting for i is correctly set.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 sound/soc/codecs/sgtl5000.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Dan Carpenter Sept. 6, 2018, 11:58 a.m. UTC | #1 
On Thu, Sep 06, 2018 at 11:41:52AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> In the case where lo_vag <= SGTL5000_LINE_OUT_GND_BASE, lo_vag
> is set to zero and later vol_quot is computed by dividing by
> lo_vag causing a division by zero error.  Fix this by avoiding
> a zero division and set vol_quot to zero in this specific case
> so that the lowest setting for i is correctly set.
> 

This is a very clever patch.  How did you find the bug?

regards,
dan carpenter
Colin King Sept. 6, 2018, 12:01 p.m. UTC | #2 
On 06/09/18 12:58, Dan Carpenter wrote:
> On Thu, Sep 06, 2018 at 11:41:52AM +0100, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> In the case where lo_vag <= SGTL5000_LINE_OUT_GND_BASE, lo_vag
>> is set to zero and later vol_quot is computed by dividing by
>> lo_vag causing a division by zero error.  Fix this by avoiding
>> a zero division and set vol_quot to zero in this specific case
>> so that the lowest setting for i is correctly set.
>>
> 
> This is a very clever patch.  How did you find the bug?

trawling through a lot of false positives from a recent cppcheck run

> 
> regards,
> dan carpenter
>
diff mbox series

Patch

diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c
index 60764f6201b1..add18d6d77da 100644
--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -1218,7 +1218,7 @@  static int sgtl5000_set_power_regs(struct snd_soc_component *component)
 	 * Searching for a suitable index solving this formula:
 	 * idx = 40 * log10(vag_val / lo_cagcntrl) + 15
 	 */
-	vol_quot = (vag * 100) / lo_vag;
+	vol_quot = lo_vag ? (vag * 100) / lo_vag : 0;
 	lo_vol = 0;
 	for (i = 0; i < ARRAY_SIZE(vol_quot_table); i++) {
 		if (vol_quot >= vol_quot_table[i])