[Intel-gfx] [PATCH] Revert "drm/i915/dp: reduce link M/N parameters"

[Dhinakaran Pandiyan]

This reverts commit 9a86cda07af2 ("drm/i915/dp: reduce link M/N
parameters"), which  causes blank screen on a certain HSW laptop. See
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100755

Cc: Clint Taylor <clinton.a.taylor at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Reported-by: Rafael Ristovski <rafael.ristovski at gmail.com>
Signed-off-by: Dhinakaran Pandiyan <dhnkrn at gmail.com>
---
 drivers/gpu/drm/i915/intel_display.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 85b9e2f5..0b05e87 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6276,17 +6276,6 @@ intel_reduce_m_n_ratio(uint32_t *num, uint32_t *den)
 static void compute_m_n(unsigned int m, unsigned int n,
 			uint32_t *ret_m, uint32_t *ret_n)
 {
-	/*
-	 * Reduce M/N as much as possible without loss in precision. Several DP
-	 * dongles in particular seem to be fussy about too large *link* M/N
-	 * values. The passed in values are more likely to have the least
-	 * significant bits zero than M after rounding below, so do this first.
-	 */
-	while ((m & 1) == 0 && (n & 1) == 0) {
-		m >>= 1;
-		n >>= 1;
-	}
-
 	*ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX);
 	*ret_m = div_u64((uint64_t) m * *ret_n, n);
 	intel_reduce_m_n_ratio(ret_m, ret_n);
-- 
2.7.4