[Intel-gfx] [PATCH] drm/i915: Changes required to enable DSI Video Mode on CHT

[Gaurav K Singh]

On CHT, changes are required for calculating the correct m,n & p with
minimal error +/- for the required DSI clock, so that the correct dividor
& ctrl values are written in cck regs for DSI. This patch has been tested
on CHT RVP with 1200 x 1920 panel.

Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>
---
 drivers/gpu/drm/i915/intel_dsi_pll.c |   43 ++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
index 3622d0b..b7a94c2 100644
--- a/drivers/gpu/drm/i915/intel_dsi_pll.c
+++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
@@ -162,7 +162,8 @@ static u32 dsi_clk_from_pclk(u32 pclk, int pixel_format, int lane_count)
 
 #endif
 
-static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
+static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
+			u32 dsi_clk, struct dsi_mnp *dsi_mnp)
 {
 	u32 m, n, p;
 	u32 ref_clk;
@@ -173,6 +174,10 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
 	u32 calc_m;
 	u32 calc_p;
 	u32 m_seed;
+	u32 m_start;
+	u32 m_limit;
+	u32 n_limit;
+	u32 p_limit;
 
 	/* dsi_clk is expected in KHZ */
 	if (dsi_clk < 300000 || dsi_clk > 1150000) {
@@ -180,18 +185,33 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
 		return -ECHRNG;
 	}
 
-	ref_clk = 25000;
+	if (IS_CHERRYVIEW(dev_priv->dev)) {
+		ref_clk = 100000;
+		m_start = 70;
+		m_limit = 96;
+		n_limit = 4;
+		p_limit = 6;
+	} else if (IS_VALLEYVIEW(dev_priv->dev)) {
+		ref_clk = 25000;
+		m_start = 62;
+		m_limit = 92;
+		n_limit = 1;
+		p_limit = 6;
+	} else {
+		DRM_ERROR("Unsupported device\n");
+		return -ENODEV;
+	}
 	target_dsi_clk = dsi_clk;
 	error = 0xFFFFFFFF;
 	tmp_error = 0xFFFFFFFF;
 	calc_m = 0;
 	calc_p = 0;
 
-	for (m = 62; m <= 92; m++) {
-		for (p = 2; p <= 6; p++) {
+	for (m = m_start; m <= m_limit; m++) {
+		for (p = 2; p <= p_limit; p++) {
 			/* Find the optimal m and p divisors
 			   with minimal error +/- the required clock */
-			calc_dsi_clk = (m * ref_clk) / p;
+			calc_dsi_clk = (m * ref_clk) / (p * n_limit);
 			if (calc_dsi_clk == target_dsi_clk) {
 				calc_m = m;
 				calc_p = p;
@@ -212,11 +232,14 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
 	}
 
 	m_seed = lfsr_converts[calc_m - 62];
-	n = 1;
+	n = n_limit;
 	dsi_mnp->dsi_pll_ctrl = 1 << (DSI_PLL_P1_POST_DIV_SHIFT + calc_p - 2);
-	dsi_mnp->dsi_pll_div = (n - 1) << DSI_PLL_N1_DIV_SHIFT |
-		m_seed << DSI_PLL_M1_DIV_SHIFT;
-
+	if (IS_CHERRYVIEW(dev_priv->dev))
+		dsi_mnp->dsi_pll_div = (n/2) << DSI_PLL_N1_DIV_SHIFT |
+				m_seed << DSI_PLL_M1_DIV_SHIFT;
+	else
+		dsi_mnp->dsi_pll_div = (n - 1) << DSI_PLL_N1_DIV_SHIFT |
+				m_seed << DSI_PLL_M1_DIV_SHIFT;
 	return 0;
 }
 
@@ -235,7 +258,7 @@ static void vlv_configure_dsi_pll(struct intel_encoder *encoder)
 	dsi_clk = dsi_clk_from_pclk(intel_dsi->pclk, intel_dsi->pixel_format,
 				    intel_dsi->lane_count);
 
-	ret = dsi_calc_mnp(dsi_clk, &dsi_mnp);
+	ret = dsi_calc_mnp(dev_priv, dsi_clk, &dsi_mnp);
 	if (ret) {
 		DRM_DEBUG_KMS("dsi_calc_mnp failed\n");
 		return;
-- 
1.7.9.5