[Intel-gfx] [PATCH 06/14] drm/i915: De-magic the VLV p2 divider step size

ville.syrjala at linux.intel.com ville.syrjala at linux.intel.com
Tue Sep 24 20:26:23 CEST 2013


From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The p2 divider on VLV needs to be even when it's > 10. The current code
to make that happen is rather weird. Just make the step size adjustement
in the for loop decrement step.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c5f0794..330fefc 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -687,9 +687,8 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc,
 	/* based on hardware requirement, prefer smaller n to precision */
 	for (clock.n = limit->n.min; clock.n <= ((refclk) / minupdate); clock.n++) {
 		for (clock.p1 = limit->p1.max; clock.p1 > limit->p1.min; clock.p1--) {
-			for (clock.p2 = limit->p2.p2_fast+1; clock.p2 > 0; clock.p2--) {
-				if (clock.p2 > 10)
-					clock.p2--;
+			for (clock.p2 = limit->p2.p2_fast; clock.p2 > 0;
+			     clock.p2 -= clock.p2 > 10 ? 2 : 1) {
 				clock.p = clock.p1 * clock.p2;
 				/* based on hardware requirement, prefer bigger m1,m2 values */
 				for (clock.m1 = limit->m1.min; clock.m1 <= limit->m1.max; clock.m1++) {
-- 
1.8.1.5




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