[PATCH][next] drm/mgag200: Fix uninitialized variable delta

[PATCH][next] drm/mgag200: Fix uninitialized variable delta

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The variable delta is not initialized and this will cause unexpected
behaviour with the comparison of tmpdelta < delta. Fix this by setting
it to 0xffffffff. This matches the behaviour as in the similar function
mgag200_pixpll_compute_g200se_04.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 2545ac960364 ("drm/mgag200: Abstract pixel PLL via struct mgag200_pll")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/gpu/drm/mgag200/mgag200_pll.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_pll.c b/drivers/gpu/drm/mgag200/mgag200_pll.c
index 7c903cf19c0d..18f1a6dd019a 100644
--- a/drivers/gpu/drm/mgag200/mgag200_pll.c
+++ b/drivers/gpu/drm/mgag200/mgag200_pll.c
@@ -125,6 +125,7 @@ static int mgag200_pixpll_compute_g200se_00(struct mgag200_pll *pixpll, long clo
 
 	m = n = p = s = 0;
 	permitteddelta = clock * 5 / 1000;
+	delta = 0xffffffff;
 
 	for (testp = 8; testp > 0; testp /= 2) {
 		if (clock * testp > vcomax)
-- 
2.32.0

Re: [PATCH][next] drm/mgag200: Fix uninitialized variable delta

[Thomas Zimmermann]

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Hi

Am 17.08.21 um 18:32 schrieb Colin King:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The variable delta is not initialized and this will cause unexpected
> behaviour with the comparison of tmpdelta < delta. Fix this by setting
> it to 0xffffffff. This matches the behaviour as in the similar function
> mgag200_pixpll_compute_g200se_04.
> 
> Addresses-Coverity: ("Uninitialized scalar variable")
> Fixes: 2545ac960364 ("drm/mgag200: Abstract pixel PLL via struct mgag200_pll")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

But the commit message needs Fixes etc. I just sent out a patch for this 
issue myself. I'd like to merge both patches' tags and commit the result 
under your name. (You were first.) Is that ok for you?

Best regards
Thomas

> ---
>   drivers/gpu/drm/mgag200/mgag200_pll.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_pll.c b/drivers/gpu/drm/mgag200/mgag200_pll.c
> index 7c903cf19c0d..18f1a6dd019a 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_pll.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_pll.c
> @@ -125,6 +125,7 @@ static int mgag200_pixpll_compute_g200se_00(struct mgag200_pll *pixpll, long clo
>   
>   	m = n = p = s = 0;
>   	permitteddelta = clock * 5 / 1000;
> +	delta = 0xffffffff;
>   
>   	for (testp = 8; testp > 0; testp /= 2) {
>   		if (clock * testp > vcomax)
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH][next] drm/mgag200: Fix uninitialized variable delta

[Colin Ian King]

On 17/08/2021 19:22, Thomas Zimmermann wrote:
> Hi
> 
> Am 17.08.21 um 18:32 schrieb Colin King:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> The variable delta is not initialized and this will cause unexpected
>> behaviour with the comparison of tmpdelta < delta. Fix this by setting
>> it to 0xffffffff. This matches the behaviour as in the similar function
>> mgag200_pixpll_compute_g200se_04.
>>
>> Addresses-Coverity: ("Uninitialized scalar variable")
>> Fixes: 2545ac960364 ("drm/mgag200: Abstract pixel PLL via struct
>> mgag200_pll")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> But the commit message needs Fixes etc. I just sent out a patch for this
> issue myself. I'd like to merge both patches' tags and commit the result
> under your name. (You were first.) Is that ok for you?

Sure. Go ahead, Thanks

Colin

> 
> Best regards
> Thomas
> 
>> ---
>>   drivers/gpu/drm/mgag200/mgag200_pll.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/mgag200/mgag200_pll.c
>> b/drivers/gpu/drm/mgag200/mgag200_pll.c
>> index 7c903cf19c0d..18f1a6dd019a 100644
>> --- a/drivers/gpu/drm/mgag200/mgag200_pll.c
>> +++ b/drivers/gpu/drm/mgag200/mgag200_pll.c
>> @@ -125,6 +125,7 @@ static int mgag200_pixpll_compute_g200se_00(struct
>> mgag200_pll *pixpll, long clo
>>         m = n = p = s = 0;
>>       permitteddelta = clock * 5 / 1000;
>> +    delta = 0xffffffff;
>>         for (testp = 8; testp > 0; testp /= 2) {
>>           if (clock * testp > vcomax)
>>
>