gma500: Disable the clock gating of display controller to make DP/eDP work well

I don't know why the DP/eDP is affected by the clock gating. But the test
shows that it really fixes the DP/eDP clock issue during enabling DP/eDP.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
[Updated to only apply the workaround if the device has DP. We don't want
 to do this on netbooks]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
index 0571ef9b889b..9bacce3ce53c 100644
--- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
+++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
@@ -1778,6 +1778,28 @@ static bool cdv_intel_dpc_is_edp(struct drm_device *dev)
         return false;
 }
 
+/* Cedarview display clock gating
+
+   We need this disable dot get correct behaviour while enabling
+   DP/eDP. TODO - investigate if we can turn it back to normality
+   after enabling */
+static void cdv_disable_intel_clock_gating(struct drm_device *dev)
+{
+        u32 reg_value;
+        reg_value = REG_READ(DSPCLK_GATE_D);
+
+        reg_value |= (DPUNIT_PIPEB_GATE_DISABLE |
+                        DPUNIT_PIPEA_GATE_DISABLE |
+                        DPCUNIT_CLOCK_GATE_DISABLE |
+                        DPLSUNIT_CLOCK_GATE_DISABLE |
+                        DPOUNIT_CLOCK_GATE_DISABLE |
+                        DPIOUNIT_CLOCK_GATE_DISABLE);   
+
+        REG_WRITE(DSPCLK_GATE_D, reg_value);
+
+        udelay(500);            
+}
+
 void
 cdv_intel_dp_init(struct drm_device *dev, struct psb_intel_mode_device *mode_dev, int output_reg)
 {
@@ -1841,6 +1863,8 @@ cdv_intel_dp_init(struct drm_device *dev, struct psb_intel_mode_device *mode_dev
                         break;
         }
 
+        cdv_disable_intel_clock_gating(dev);
+
         cdv_intel_dp_i2c_init(psb_intel_connector, psb_intel_encoder, name);
         /* FIXME:fail check */
         cdv_intel_dp_add_properties(connector);
diff --git a/drivers/gpu/drm/gma500/psb_intel_reg.h b/drivers/gpu/drm/gma500/psb_intel_reg.h
index 389e969e8986..d914719c4b60 100644
--- a/drivers/gpu/drm/gma500/psb_intel_reg.h
+++ b/drivers/gpu/drm/gma500/psb_intel_reg.h
@@ -1313,6 +1313,10 @@ No status bits are changed.
 # define VRHUNIT_CLOCK_GATE_DISABLE             (1 << 28) /* Fixed value on CDV */
 # define DPOUNIT_CLOCK_GATE_DISABLE             (1 << 11)
 # define DPIOUNIT_CLOCK_GATE_DISABLE            (1 << 6)
+# define DPUNIT_PIPEB_GATE_DISABLE              (1 << 30)
+# define DPUNIT_PIPEA_GATE_DISABLE              (1 << 25)
+# define DPCUNIT_CLOCK_GATE_DISABLE             (1 << 24)
+# define DPLSUNIT_CLOCK_GATE_DISABLE            (1 << 13)
 
 #define RAMCLK_GATE_D           0x6210