drm/i915/bxt: Additional MIPI clock divider form B0 stepping onwards

The MIPI clock calculations for the addtional clock
are revised from B0 stepping onwards, the bit definitions
have changed compared to old stepping.

v2: Fixing compilation warning.
v3: Retained the old Macros (Jani)

Signed-off-by: Deepak M <m.deepak@intel.com>
Tested-by: Ramalingam C <ramalingam.c@intel.com> # BXT-T with Tianma panel
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455556437-29267-1-git-send-email-m.deepak@intel.com

1 files changed, 39 insertions, 17 deletions

diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
index 70883c54cb0a..2451c84949bd 100644
--- a/drivers/gpu/drm/i915/intel_dsi_pll.c
+++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
@@ -362,35 +362,57 @@ static void vlv_dsi_reset_clocks(struct intel_encoder *encoder, enum port port)
 /* Program BXT Mipi clocks and dividers */
 static void bxt_dsi_program_clocks(struct drm_device *dev, enum port port)
 {
-	u32 tmp;
-	u32 divider;
-	u32 dsi_rate;
-	u32 pll_ratio;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 tmp;
+	u32 dsi_rate = 0;
+	u32 pll_ratio = 0;
+	u32 rx_div;
+	u32 tx_div;
+	u32 rx_div_upper;
+	u32 rx_div_lower;
+	u32 mipi_8by3_divider;
 
 	/* Clear old configurations */
 	tmp = I915_READ(BXT_MIPI_CLOCK_CTL);
 	tmp &= ~(BXT_MIPI_TX_ESCLK_FIXDIV_MASK(port));
-	tmp &= ~(BXT_MIPI_RX_ESCLK_FIXDIV_MASK(port));
-	tmp &= ~(BXT_MIPI_ESCLK_VAR_DIV_MASK(port));
-	tmp &= ~(BXT_MIPI_DPHY_DIVIDER_MASK(port));
+	tmp &= ~(BXT_MIPI_RX_ESCLK_UPPER_FIXDIV_MASK(port));
+	tmp &= ~(BXT_MIPI_8X_BY3_DIVIDER_MASK(port));
+	tmp &= ~(BXT_MIPI_RX_ESCLK_LOWER_FIXDIV_MASK(port));
 
 	/* Get the current DSI rate(actual) */
 	pll_ratio = I915_READ(BXT_DSI_PLL_CTL) &
 				BXT_DSI_PLL_RATIO_MASK;
 	dsi_rate = (BXT_REF_CLOCK_KHZ * pll_ratio) / 2;
 
-	/* Max possible output of clock is 39.5 MHz, program value -1 */
-	divider = (dsi_rate / BXT_MAX_VAR_OUTPUT_KHZ) - 1;
-	tmp |= BXT_MIPI_ESCLK_VAR_DIV(port, divider);
+	/*
+	 * tx clock should be <= 20MHz and the div value must be
+	 * subtracted by 1 as per bspec
+	 */
+	tx_div = DIV_ROUND_UP(dsi_rate, 20000) - 1;
+	/*
+	 * rx clock should be <= 150MHz and the div value must be
+	 * subtracted by 1 as per bspec
+	 */
+	rx_div = DIV_ROUND_UP(dsi_rate, 150000) - 1;
 
 	/*
-	 * Tx escape clock must be as close to 20MHz possible, but should
-	 * not exceed it. Hence select divide by 2
+	 * rx divider value needs to be updated in the
+	 * two differnt bit fields in the register hence splitting the
+	 * rx divider value accordingly
 	 */
-	tmp |= BXT_MIPI_TX_ESCLK_8XDIV_BY2(port);
+	rx_div_lower = rx_div & RX_DIVIDER_BIT_1_2;
+	rx_div_upper = (rx_div & RX_DIVIDER_BIT_3_4) >> 2;
+
+	/* As per bpsec program the 8/3X clock divider to the below value */
+	if (dev_priv->vbt.dsi.config->is_cmd_mode)
+		mipi_8by3_divider = 0x2;
+	else
+		mipi_8by3_divider = 0x3;
 
-	tmp |= BXT_MIPI_RX_ESCLK_8X_BY3(port);
+	tmp |= BXT_MIPI_8X_BY3_DIVIDER(port, mipi_8by3_divider);
+	tmp |= BXT_MIPI_TX_ESCLK_DIVIDER(port, tx_div);
+	tmp |= BXT_MIPI_RX_ESCLK_LOWER_DIVIDER(port, rx_div_lower);
+	tmp |= BXT_MIPI_RX_ESCLK_UPPER_DIVIDER(port, rx_div_upper);
 
 	I915_WRITE(BXT_MIPI_CLOCK_CTL, tmp);
 }
@@ -513,9 +535,9 @@ static void bxt_dsi_reset_clocks(struct intel_encoder *encoder, enum port port)
 	/* Clear old configurations */
 	tmp = I915_READ(BXT_MIPI_CLOCK_CTL);
 	tmp &= ~(BXT_MIPI_TX_ESCLK_FIXDIV_MASK(port));
-	tmp &= ~(BXT_MIPI_RX_ESCLK_FIXDIV_MASK(port));
-	tmp &= ~(BXT_MIPI_ESCLK_VAR_DIV_MASK(port));
-	tmp &= ~(BXT_MIPI_DPHY_DIVIDER_MASK(port));
+	tmp &= ~(BXT_MIPI_RX_ESCLK_UPPER_FIXDIV_MASK(port));
+	tmp &= ~(BXT_MIPI_8X_BY3_DIVIDER_MASK(port));
+	tmp &= ~(BXT_MIPI_RX_ESCLK_LOWER_FIXDIV_MASK(port));
 	I915_WRITE(BXT_MIPI_CLOCK_CTL, tmp);
 	I915_WRITE(MIPI_EOT_DISABLE(port), CLOCKSTOP);
 }