Re: [PATCH v2 06/20] drm/i915: Allow fuzzy matching in pipe_config_compare.

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jul 08, 2015 at 10:38:33AM +0200, Maarten Lankhorst wrote:
> Op 07-07-15 om 12:11 schreef Daniel Vetter:
> > On Tue, Jul 07, 2015 at 09:08:17AM +0200, Maarten Lankhorst wrote:
> >> @@ -12392,27 +12379,124 @@ static bool intel_fuzzy_clock_check(int clock1, int clock2)
> >>  			    base.head) \
> >>  		if (mask & (1 <<(intel_crtc)->pipe))
> >>  
> >> +
> >> +static bool
> >> +intel_compare_m_n(unsigned int m, unsigned int n,
> >> +		  unsigned int m2, unsigned int n2)
> >> +{
> >> +	if (m == m2 && n == n2)
> >> +		return true;
> >> +
> >> +	if (!m || !n || !m2 || !n2)
> >> +		return false;
> >> +
> >> +	if (m > m2) {
> >> +		while (m > m2) {
> > I think we need to make sure we don't reduce precision by eating low bits,
> > i.e.
> > 		while (m > m2 && !(m & 1) && !(n & 1)) {
> Could be useful, lets hope everyone rounds in the same way. :)
> >> +			m >>= 1;
> >> +			n >>= 1;
> >> +		}
> >> +	} else if (m < m2) {
> >> +		while (m < m2) {
> >> +			m2 >>= 1;
> >> +			n2 >>= 1;
> >> +		}
> >> +	}
> >> +
> >> +	return m == m2 && n == n2;
> >> +}
> >> +
> >> +static bool
> >> +intel_compare_link_m_n(const struct intel_link_m_n *m_n,
> >> +		       const struct intel_link_m_n *m2_n2)
> > I think these need to take adjust as an agurment and check for exact match
> > (not just matching ratio), like before.
> I just implemented it, then remembered why I didn't.
> 
> It will cause a failure in intel_modeset_check_state.

That shouldn't happen. I guess the bug is that adjust doesn't live up to
it's name and doesn't copy the current value over to the new config if
they're compatible?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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