[Intel-gfx] [PATCH 5/5] drm/i915: Add SPLL sharing support for DDI

[ville.syrjala at linux.intel.com]

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

Write some theoretical SPLL sharing support for DDI. Currently that will
never happens since we never use SPLL for anything but FDI. But having
the code there makes it easier if we ever want to do it, and it might
excercise the PLL sharing code a bit more.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_ddi.c | 45 ++++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 2643d3b..1dbe3e4 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -870,16 +870,35 @@ bool intel_ddi_pll_select(struct intel_crtc *intel_crtc)
 		}
 
 	} else if (type == INTEL_OUTPUT_ANALOG) {
-		if (plls->spll_refcount == 0) {
+		uint32_t val = SPLL_PLL_ENABLE | SPLL_PLL_SSC;
+
+		switch (clock / 2) {
+		case 81000:
+			val |= SPLL_PLL_FREQ_810MHz;
+			break;
+		case 135000:
+			val |= SPLL_PLL_FREQ_1350MHz;
+			break;
+		case 270000:
+			val |= SPLL_PLL_FREQ_2700MHz;
+			break;
+		default:
+			DRM_ERROR("SPLL frequency %d kHz unsupported\n", clock / 2);
+			return false;
+		}
+
+		if (val == I915_READ(SPLL_CTL)) {
+			DRM_DEBUG_KMS("Reusing SPLL on pipe %c\n",
+				      pipe_name(pipe));
+		} else if (plls->spll_refcount == 0) {
 			DRM_DEBUG_KMS("Using SPLL on pipe %c\n",
 				      pipe_name(pipe));
-			plls->spll_refcount++;
-			intel_crtc->ddi_pll_sel = PORT_CLK_SEL_SPLL;
 		} else {
 			DRM_ERROR("SPLL already in use\n");
 			return false;
 		}
-
+		plls->spll_refcount++;
+		intel_crtc->ddi_pll_sel = PORT_CLK_SEL_SPLL;
 	} else {
 		WARN(1, "Invalid DDI encoder type %d\n", type);
 		return false;
@@ -921,8 +940,22 @@ void intel_ddi_pll_enable(struct intel_crtc *crtc)
 		pll_name = "SPLL";
 		reg = SPLL_CTL;
 		refcount = plls->spll_refcount;
-		new_val = SPLL_PLL_ENABLE | SPLL_PLL_FREQ_1350MHz |
-			  SPLL_PLL_SSC;
+		new_val = SPLL_PLL_ENABLE | SPLL_PLL_SSC;
+
+		switch (clock / 2) {
+		case 81000:
+			new_val |= SPLL_PLL_FREQ_810MHz;
+			break;
+		case 135000:
+			new_val |= SPLL_PLL_FREQ_1350MHz;
+			break;
+		case 270000:
+			new_val |= SPLL_PLL_FREQ_2700MHz;
+			break;
+		default:
+			WARN(1, "Bad SPLL frequency %d\n", clock / 2);
+			return;
+		}
 		break;
 
 	case PORT_CLK_SEL_WRPLL1:
-- 
1.8.3.2