On Sunday 23 October 2016 12:22:13 Pavel Machek wrote:
> Hi!
> 
> I tried to update camera code on n900 to v4.9-rc1, and I'm getting
> some divide by zero, that eventually cascades into fcam-dev not
> working.
> 
> mul is zero in my testing, resulting in divide by zero.
> 
> (Note that this is going from my patched camera-v4.8 tree to
> camera-v4.9 tree.)
> 
> Best regards,
> 								Pavel

Hi! Ideally look at existing camera patches. I do not know which one is
last, but here are some links:

https://github.com/freemangordon/linux-n900/tree/v4.6-rc4-n900-camera
https://github.com/freemangordon/linux-n900/tree/camera
https://git.kernel.org/cgit/linux/kernel/git/sre/linux-n900.git/log/?h=n900-camera-ivo
https://git.kernel.org/cgit/linux/kernel/git/sre/linux-n900.git/log/?h=n900-camera

> diff --git a/drivers/media/i2c/smiapp-pll.c
> b/drivers/media/i2c/smiapp-pll.c index 5ad1edb..e0a6edd 100644
> --- a/drivers/media/i2c/smiapp-pll.c
> +++ b/drivers/media/i2c/smiapp-pll.c
> @@ -16,6 +16,8 @@
>   * General Public License for more details.
>   */
> 
> +#define DEBUG
> +
>  #include <linux/device.h>
>  #include <linux/gcd.h>
>  #include <linux/lcm.h>
> @@ -457,6 +459,10 @@ int smiapp_pll_calculate(struct device *dev,
>  	i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
>  	mul = div_u64(pll->pll_op_clk_freq_hz, i);
>  	div = pll->ext_clk_freq_hz / i;
> +	if (!mul) {
> +		dev_err(dev, "forcing mul to 1\n");
> +		mul = 1;
> +	}
>  	dev_dbg(dev, "mul %u / div %u\n", mul, div);
> 
>  	min_pre_pll_clk_div =

Is not this patch still enough?
https://patchwork.kernel.org/patch/8921761/

-- 
Pali Rohár
pali.rohar@gmail.com