drm/i915: workaround IGD i2c bus issue in kernel side (v2)
In IGD, DPCUNIT_CLOCK_GATE_DISABLE bit should be set, otherwise i2c
access will be wrong.
v2: Disable CLOCK_GATE_DISABLE bit after bit bashing as suggested by Eric.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 5ee9d4c..f7061f6 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -34,6 +34,21 @@
#include "i915_drm.h"
#include "i915_drv.h"
+void intel_i2c_quirk_set(struct drm_device *dev, bool enable)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+
+ /* When using bit bashing for I2C, this bit needs to be set to 1 */
+ if (!IS_IGD(dev))
+ return;
+ if (enable)
+ I915_WRITE(CG_2D_DIS,
+ I915_READ(CG_2D_DIS) | DPCUNIT_CLOCK_GATE_DISABLE);
+ else
+ I915_WRITE(CG_2D_DIS,
+ I915_READ(CG_2D_DIS) & (~DPCUNIT_CLOCK_GATE_DISABLE));
+}
+
/*
* Intel GPIO access functions
*/
@@ -153,8 +168,10 @@
goto out_free;
/* JJJ: raise SCL and SDA? */
+ intel_i2c_quirk_set(dev, true);
set_data(chan, 1);
set_clock(chan, 1);
+ intel_i2c_quirk_set(dev, false);
udelay(20);
return chan;