Re: drm/mgag200: don't use uninitialized variables in mga_g200se_set_plls()

[Mathieu Larouche <mathieu.larouche@matrox.com>]

On 20/10/2015 11:00 AM, Jan Beulich wrote:
>>>> On 20.10.15 at 16:47, <mathieu.larouche@matrox.com> wrote:
>> On 19/10/2015 6:29 AM, Jan Beulich wrote:
>>> --- 4.3-rc6/drivers/gpu/drm/mgag200/mgag200_mode.c
>>> +++ 4.3-rc6-mgag200-uninit/drivers/gpu/drm/mgag200/mgag200_mode.c
>>> @@ -194,7 +194,7 @@ static int mga_g200se_set_plls(struct mg
>>>    			}
>>>    		}
>>>    
>>> -		fvv = pllreffreq * testn / testm;
>>> +		fvv = pllreffreq * n / m;
>>>    		fvv = (fvv - 800000) / 50000;
>>>    
>>>    		if (fvv > 15)
>>>
>> If you are using n/m instead of testn/testm, you need to
>> add 1 to the variables to keep consistency. However, you
>> have the same issue where m/n could be used without being
>> initialized. So, I propose to keep testm, testn & testp
>> and initialized them with the default value.
> That makes them initialized, but since testn and testm are used
> as loop variables I don't see how initializing them to default
> values helps overcome the other half of the problem described
> (them having a constant, pre-determined value at the end of
> the loops: testn=257, testm=33). As to testp - it is always
> initialized anyway (so long as P_ARRAY_SIZE is not zero). And
> in the if() branch initialization isn't needed either, since the
> variables aren't being used after the loops.
>
> Jan
>
>
Sorry, I missed that part in your initial comment and you are right,
there's an issue there. So, your proposed patch totally make sense,
you only need to add 1 to m/n.

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