[PATCH v12 3/6] fbmon: add videomode helpers

[Laurent Pinchart]

Hi Sascha,

On Thursday 22 November 2012 07:20:00 Sascha Hauer wrote:
> On Wed, Nov 21, 2012 at 11:02:44PM +0100, Laurent Pinchart wrote:
> > Hi Steffen,
> > 
> > > +
> > > +	htotal = vm->hactive + vm->hfront_porch + vm->hback_porch +
> > > +		 vm->hsync_len;
> > > +	vtotal = vm->vactive + vm->vfront_porch + vm->vback_porch +
> > > +		 vm->vsync_len;
> > > +	fbmode->refresh = (vm->pixelclock * 1000) / (htotal * vtotal);
> > 
> > This will fail if vm->pixelclock >= ((1 << 32) / 1000). The easiest
> > solution is probably to use 64-bit computation.
> 
> You have displays with a pixelclock > 4GHz?

vm->pixelclock is expressed in Hz. vm->pixelclock * 1000 will thus overflow if 
the clock frequency is >= ~4.3 MHz. I have displays with a clock frequency 
higher than that :-)

-- 
Regards,

Laurent Pinchart