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drm/i915: use gmbus irq to wait for gmbus idle

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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).

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-12-01 13:53:46 +01:00
parent 28c70f162a
commit 2c438c0273
1 changed files with 28 additions and 4 deletions
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32
drivers/gpu/drm/i915/intel_i2c.c
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@ -203,6 +203,7 @@ 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,
@ -239,6 +240,31 @@ gmbus_wait_hw_status(struct drm_i915_private *dev_priv,
return -ETIMEDOUT;
}
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)
@ -406,8 +432,7 @@ 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;
@ -431,8 +456,7 @@ 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;