Re: [PATCH] cx18: Use do_div for 64-bit division to fix 32-bit kernels

[David Ward <david.ward@gatech.edu>]

On 05/29/2009 07:09 AM, Andy Walls wrote:
> On Thu, 2009-05-28 at 20:27 -0400, David Ward wrote:
>    
>> Use the do_div macro for 64-bit division.  Otherwise, the module will
>> reference __udivdi3 under 32-bit kernels, which is not allowed in kernel
>> space.  Follows style used in cx88 module.
>>      
> Ooopsie.  Thanks for catching this and providing a fix. :)
>
> (FYI, You would have caught my attention earlier if you had put "cx18:"
> in the subject line of the initital report.)
>
> I'll test it tonight on my 64 bit machine, commit it, and ask Mauro to
> pull it.  I assume you've tested it on your 32 bit machine.
>
> Regards,
> Andy
>
>    
Thanks Andy.  Yes it's running on my 32-bit system.  Until Michael 
pointed out the offending line of code, I didn't realize that the 
problem I was seeing was specific to the cx18 module -- I figured that 
the problem could just as easily have been in an include somewhere and 
affected multiple modules, perhaps only under older kernels -- so that's 
why my original subject line was generic.  But I'll keep that in mind in 
the future.

David
>> Signed-off-by: David Ward<david.ward@gatech.edu>
>>
>> diff -r 65ec132f20df -r 91b89f13adb7
>> linux/drivers/media/video/cx18/cx18-av-core.c
>> --- a/linux/drivers/media/video/cx18/cx18-av-core.c    Wed May 27
>> 15:53:00 2009 -0300
>> +++ b/linux/drivers/media/video/cx18/cx18-av-core.c    Thu May 28
>> 19:16:10 2009 -0400
>> @@ -447,6 +447,7 @@ void cx18_av_std_setup(struct cx18 *cx)
>>
>>        if (pll_post) {
>>            int fsc, pll;
>> +        u64 tmp64;
>>
>>            pll = (28636360L * ((((u64)pll_int)<<  25) + pll_frac))>>  25;
>>            pll /= pll_post;
>> @@ -459,7 +460,9 @@ void cx18_av_std_setup(struct cx18 *cx)
>>                        "= %d.%03d\n", src_decimation / 256,
>>                        ((src_decimation % 256) * 1000) / 256);
>>
>> -        fsc = ((((u64)sc) * 28636360)/src_decimation)>>  13L;
>> +        tmp64 = ((u64)sc) * 28636360;
>> +        do_div(tmp64, src_decimation);
>> +        fsc = ((u32)(tmp64>>  13L));
>>            CX18_DEBUG_INFO_DEV(sd,
>>                        "Chroma sub-carrier initial freq = %d.%06d "
>>                        "MHz\n", fsc / 1000000, fsc % 1000000)
>>