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@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reported-by: Rafael Ristovski <rafael.ristovski@xxxxxxxxx>
Signed-off-by: Dhinakaran Pandiyan <dhnkrn@xxxxxxxxx>
---
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
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