From 2c438c0273b76d6cb158f8bdd0aa3ebf66e48a28 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sat, 1 Dec 2012 13:53:46 +0100 Subject: [PATCH] drm/i915: use gmbus irq to wait for gmbus idle 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 Signed-off-by: Daniel Vetter --- 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 8b71892..1fc3119 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -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, @@ -240,6 +241,31 @@ 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) { @@ -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; -- 2.7.4