[Intel-gfx] [PATCH 2/2] drm/i915: cleanup Valleyview PLL calculation

[Vijay Purushothaman]

replaced hardcoded numbers with valid PLL limit values

Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |   52 +++++++++++++--------------------
 1 files changed, 21 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0707b7a..e2d23a3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -865,69 +865,59 @@ intel_vlv_find_best_pll(const intel_limit_t *limit, struct drm_crtc *crtc,
 			intel_clock_t *best_clock)
 {
 	u32 p1, p2, m1, m2, vco, bestn, bestm1, bestm2, bestp1, bestp2;
-	u32 m, n, fastclk, minvco, maxvco;
+	u32 m, n, fastclk;
 	u32 updrate, minupdate, fracbits, p;
 	unsigned long bestppm, ppm, absppm;
-	int dotclk;
+	int dotclk, flag;
 
 	dotclk = target * 1000;
-
 	bestppm = 1000000;
-	ppm = 0;
-	absppm = 0;
-
+	ppm = absppm = 0;
 	fastclk = dotclk / (2*100);
-	minvco = limit->vco.min;
-	maxvco = limit->vco.max;
 	updrate = 0;
 	minupdate = 19200;
 	fracbits = 1;
-
 	n = p = p1 = p2 = m = m1 = m2 = vco = bestn = 0;
 	bestm1 = bestm2 = bestp1 = bestp2 = 0;
 
-	for(n = 1; n <= ((refclk) / minupdate); n++) {
+	/* based on hardware requirement, prefer smaller n to precision */
+	for (n = limit->n.min; n <= ((refclk) / minupdate); n++) {
 		updrate = refclk / n;
-		for (p1 = 3; p1 > 1; p1--) {
-			for (p2 = 21; p2 > 0; p2--) {
+		for (p1 = limit->p1.max; p1 > limit->p1.min; p1--) {
+			for (p2 = limit->p2.p2_fast+1; p2 > 0; p2--) {
 				if (p2 > 10)
 					p2 = p2 - 1;
 				p = p1 * p2;
-
-				for( m1=2; m1 <= 3; m1++) {
+				/* based on hardware requirement, prefer bigger m1,m2 values */
+				for (m1 = limit->m1.min; m1 <= limit->m1.max; m1++) {
 					m2 = (((2*(fastclk * p * n / m1 )) +
 					       refclk) / (2*refclk));
 					m = m1 * m2;
 					vco = updrate * m;
-					if(vco >= minvco && vco < maxvco) {
-						ppm = 1000000 *((vco / p) -
-								fastclk) /
-							fastclk;
-						absppm = (ppm > 0)? ppm: (-ppm);
-						if (absppm < 100 &&
-						    ((p1 * p2) >
-						     (bestp1 * bestp2))) {
+					if (vco >= limit->vco.min && vco < limit->vco.max) {
+						ppm = 1000000 * ((vco / p) - fastclk) / fastclk;
+						absppm = (ppm > 0) ? ppm : (-ppm);
+						if (absppm < 100 && ((p1 * p2) > (bestp1 * bestp2))) {
 							bestppm = 0;
-							bestn = n;
-							bestm1 = m1;
-							bestm2 = m2;
-							bestp1 = p1;
-							bestp2 = p2;
+							flag = 1;
 						}
 						if (absppm < bestppm - 10) {
 							bestppm = absppm;
+							flag = 1;
+						}
+						if (flag) {
 							bestn = n;
 							bestm1 = m1;
 							bestm2 = m2;
 							bestp1 = p1;
 							bestp2 = p2;
+							flag = 0;
 						}
 					}
 				}
-			} /* Next p2 */
-		} /* Next p1 */
-	}/* Next n */
-
+			}
+		}
+	}
 	best_clock->n = bestn;
 	best_clock->m1 = bestm1;
 	best_clock->m2 = bestm2;
-- 
1.7.5.4