drm/i915: Add MIPI_IO WA and program DSI regulators

Enable MIPI IO WA for BXT DSI as per bspec and
program the DSI regulators.

v2: Moved IO enable to pre-enable as per Mika's
review comments. Also reused the existing register
definition for BXT_P_CR_GT_DISP_PWRON.

v3: Added Programming the DSI regulators as per disable/enable
sequences.

v4: Restricting regulator changes to BXT as suggested by
Jani/Mika

v5: Removed redundant read/modify for regulator register as
per Jani's comment. Maintain enable/disable symmetry as per spec.
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
Acked-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1485353603-11260-1-git-send-email-vidya.srinivas@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -1552,6 +1552,7 @@ enum skl_disp_power_wells {
 	_MMIO(_BXT_PHY_CH(phy, ch, reg_ch0, reg_ch1))
 
 #define BXT_P_CR_GT_DISP_PWRON		_MMIO(0x138090)
+#define  MIPIO_RST_CTRL				(1 << 2)
 
 #define _BXT_PHY_CTL_DDI_A		0x64C00
 #define _BXT_PHY_CTL_DDI_B		0x64C10
@@ -8361,6 +8362,12 @@ enum {
 #define _BXT_MIPIC_PORT_CTRL				0x6B8C0
 #define BXT_MIPI_PORT_CTRL(tc)	_MMIO_MIPI(tc, _BXT_MIPIA_PORT_CTRL, _BXT_MIPIC_PORT_CTRL)
 
+#define BXT_P_DSI_REGULATOR_CFG			_MMIO(0x160020)
+#define  STAP_SELECT					(1 << 0)
+
+#define BXT_P_DSI_REGULATOR_TX_CTRL		_MMIO(0x160054)
+#define  HS_IO_CTRL_SELECT				(1 << 0)
+
 #define  DPI_ENABLE					(1 << 31) /* A + C */
 #define  MIPIA_MIPI4DPHY_DELAY_COUNT_SHIFT		27
 #define  MIPIA_MIPI4DPHY_DELAY_COUNT_MASK		(0xf << 27)

drivers/gpu/drm/i915/intel_dsi.c

@@ -548,6 +548,7 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
 	enum port port;
+	u32 val;
 
 	DRM_DEBUG_KMS("\n");
 
@@ -558,6 +559,17 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder,
 	intel_disable_dsi_pll(encoder);
 	intel_enable_dsi_pll(encoder, pipe_config);
 
+	if (IS_BROXTON(dev_priv)) {
+		/* Add MIPI IO reset programming for modeset */
+		val = I915_READ(BXT_P_CR_GT_DISP_PWRON);
+		I915_WRITE(BXT_P_CR_GT_DISP_PWRON,
+					val | MIPIO_RST_CTRL);
+
+		/* Power up DSI regulator */
+		I915_WRITE(BXT_P_DSI_REGULATOR_CFG, STAP_SELECT);
+		I915_WRITE(BXT_P_DSI_REGULATOR_TX_CTRL, 0);
+	}
+
 	intel_dsi_prepare(encoder, pipe_config);
 
 	/* Panel Enable over CRC PMIC */
@@ -707,6 +719,7 @@ static void intel_dsi_post_disable(struct intel_encoder *encoder,
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	u32 val;
 
 	DRM_DEBUG_KMS("\n");
 
@@ -714,6 +727,17 @@ static void intel_dsi_post_disable(struct intel_encoder *encoder,
 
 	intel_dsi_clear_device_ready(encoder);
 
+	if (IS_BROXTON(dev_priv)) {
+		/* Power down DSI regulator to save power */
+		I915_WRITE(BXT_P_DSI_REGULATOR_CFG, STAP_SELECT);
+		I915_WRITE(BXT_P_DSI_REGULATOR_TX_CTRL, HS_IO_CTRL_SELECT);
+
+		/* Add MIPI IO reset programming for modeset */
+		val = I915_READ(BXT_P_CR_GT_DISP_PWRON);
+		I915_WRITE(BXT_P_CR_GT_DISP_PWRON,
+				val & ~MIPIO_RST_CTRL);
+	}
+
 	intel_disable_dsi_pll(encoder);
 
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {