linux-kernel - Re: [PATCH -next] fbdev: radeon: Avoid 64 bit divide

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Message-ID: <5572053A.6060903@roeck-us.net>
Date:	Fri, 05 Jun 2015 13:23:22 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Tina Ruchandani <ruchandani.tina@...il.com>
Subject: Re: [PATCH -next] fbdev: radeon: Avoid 64 bit divide

On 06/05/2015 01:08 PM, Benjamin Herrenschmidt wrote:
> On Fri, 2015-06-05 at 11:05 -0700, Guenter Roeck wrote:
>> A 64 bit divide causes build failures with 32 bit builds, such as
>>
>> ERROR: "__divdi3" [drivers/video/fbdev/aty/radeonfb.ko] undefined!
>>
>> or
>>
>> drivers/built-in.o: In function `radeon_probe_pll_params':
>> radeon_base.c:(.text+0x16608b): undefined reference to `__divdi3'
>
> What about using do_div() instead ?
>

delta is known to be <= 10*1000000, so I figured that would have been overkill.
But, sure, at the end it is the same. Want me to resubmit ?

Guenter

>> Fixes: ce8f4069dce8 ("fbdev: radeon: Remove 'struct timeval' usage")
>> Cc: Tina Ruchandani <ruchandani.tina@...il.com>
>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>> ---
>>   drivers/video/fbdev/aty/radeon_base.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c
>> index b3612e30d74f..374e47532035 100644
>> --- a/drivers/video/fbdev/aty/radeon_base.c
>> +++ b/drivers/video/fbdev/aty/radeon_base.c
>> @@ -492,7 +492,7 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
>>   	/* Return -1 if more than 10 seconds have elapsed */
>>   	if (delta > (10*1000000))
>>   		return -1;
>> -	hz = 1000000/delta;
>> +	hz = 1000000 / (int)delta;
>>
>>   	hTotal = ((INREG(CRTC_H_TOTAL_DISP) & 0x1ff) + 1) * 8;
>>   	vTotal = ((INREG(CRTC_V_TOTAL_DISP) & 0x3ff) + 1);
>
>
>

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