On Wed, Jan 06, 2016 at 01:54:43PM +0100, Maarten Lankhorst wrote: > This prevents a unnecessary modeset on a dell XPS 13 (2016). > > N is always a power of 2, which means that for fuzzy matching we should > compare for inequality on the n values, then do fuzzy matching on the m > values. > > Signed-off-by: Maarten Lankhorst <[email protected]> > Tested-by:
Wasn't sure about overflow risks, but as long as the value we compute originally computed didn't overflow this should be safe. Reviewed-by: Daniel Vetter <[email protected]> > -- > diff --git a/drivers/gpu/drm/i915/intel_display.c > b/drivers/gpu/drm/i915/intel_display.c > index 7afbdc45a278..aa4f1e69b92e 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -12638,19 +12638,22 @@ intel_compare_m_n(unsigned int m, unsigned int n, > > BUILD_BUG_ON(DATA_LINK_M_N_MASK > INT_MAX); > > - if (m > m2) { > - while (m > m2) { > + if (n > n2) { > + while (n > n2) { > m2 <<= 1; > n2 <<= 1; > } > - } else if (m < m2) { > - while (m < m2) { > + } else if (n < n2) { > + while (n < n2) { > m <<= 1; > n <<= 1; > } > } > > - return m == m2 && n == n2; > + if (n != n2) > + return false; > + > + return intel_fuzzy_clock_check(m, m2); > } > > static bool > > _______________________________________________ > Intel-gfx mailing list > [email protected] > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
