GMBUS_ACTIVE has inverted sense and so doesn't fit into the
wait_hw_status helper, hence create a new gmbus_wait_idle functions.
Also, we only care about the idle irq event and nothing else, which
allows us to use the wait_event_timeout helper directly without
jumping through hoops to catch NAKs.
Since gen2/3 don't have gmbus interrupts, handle them separately with
the old wait_for macro.
This shaves another few ms off reading EDID from a hdmi screen on my
testbox here. EDID reading with interrupt driven gmbus is now as fast
as with busy-looping gmbus at 28 ms here (with negligible cpu
overhead).
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/gpu/drm/i915/intel_i2c.c | 32 ++++++++++++++++++++++++++++----
1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 7413595..4a38a30 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -204,6 +204,7 @@ intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
algo->data = bus;
}
+#define HAS_GMBUS_IRQ(dev) (INTEL_INFO(dev)->gen >= 4)
static int
gmbus_wait_hw_status(struct drm_i915_private *dev_priv,
u32 gmbus2_status,
@@ -241,6 +242,31 @@ gmbus_wait_hw_status(struct drm_i915_private *dev_priv,
}
static int
+gmbus_wait_idle(struct drm_i915_private *dev_priv)
+{
+ int ret;
+ int reg_offset = dev_priv->gpio_mmio_base;
+
+#define C ((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0)
+
+ if (!HAS_GMBUS_IRQ(dev_priv->dev))
+ return wait_for(C, 10);
+
+ /* Important: The hw handles only the first bit, so set only one! */
+ I915_WRITE(GMBUS4 + reg_offset, GMBUS_IDLE_EN);
+
+ ret = wait_event_timeout(dev_priv->gmbus_wait_queue, C, 10);
+
+ I915_WRITE(GMBUS4 + reg_offset, 0);
+
+ if (ret)
+ return 0;
+ else
+ return -ETIMEDOUT;
+#undef C
+}
+
+static int
gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
u32 gmbus1_index)
{
@@ -407,8 +433,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
* We will re-enable it at the start of the next xfer,
* till then let it sleep.
*/
- if (wait_for((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0,
- 10)) {
+ if (gmbus_wait_idle(dev_priv)) {
DRM_DEBUG_KMS("GMBUS [%s] timed out waiting for idle\n",
adapter->name);
ret = -ETIMEDOUT;
@@ -432,8 +457,7 @@ clear_err:
* it's slow responding and only answers on the 2nd retry.
*/
ret = -ENXIO;
- if (wait_for((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0,
- 10)) {
+ if (gmbus_wait_idle(dev_priv)) {
DRM_DEBUG_KMS("GMBUS [%s] timed out after NAK\n",
adapter->name);
ret = -ETIMEDOUT;
--
1.7.11.2
