From 31d10b5701964ed8806193807279ee7b4235e491 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Wed, 6 Jan 2016 13:54:43 +0100 Subject: [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n 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 Tested-by: Kenneth Graunke Reviewed-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/568D0E93.304@linux.intel.com --- drivers/gpu/drm/i915/intel_display.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 043adfa65203..ab0b406ee8ca 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12577,19 +12577,22 @@ 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 -- 2.20.1