From 8102e126c0827b5336065fd86d3d313b60fde23a Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 10 Feb 2011 10:05:35 +0000 Subject: [PATCH] drm/i915/tv: Use polling rather than interrupt-based hotplug The documentation recommends that we should use a polling method for TV detection as this is more power efficient than the interrupt based mechanism (as the encoder can be completely switched off). A secondary effect is that leaving the hotplug enabled seems to be causing pipe underruns as reported by Hugh Dickins on his Crestline. Tested-by: Hugh Dickins Signed-off-by: Chris Wilson [This is a candidate for stable, but needs minor porting to 2.6.37] --- drivers/gpu/drm/i915/intel_tv.c | 43 +++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c index 93206e4eaa6f..fe4a53a50b83 100644 --- a/drivers/gpu/drm/i915/intel_tv.c +++ b/drivers/gpu/drm/i915/intel_tv.c @@ -1234,7 +1234,8 @@ static const struct drm_display_mode reported_modes[] = { * \return false if TV is disconnected. */ static int -intel_tv_detect_type (struct intel_tv *intel_tv) +intel_tv_detect_type (struct intel_tv *intel_tv, + struct drm_connector *connector) { struct drm_encoder *encoder = &intel_tv->base.base; struct drm_device *dev = encoder->dev; @@ -1245,11 +1246,13 @@ intel_tv_detect_type (struct intel_tv *intel_tv) int type; /* Disable TV interrupts around load detect or we'll recurse */ - spin_lock_irqsave(&dev_priv->irq_lock, irqflags); - i915_disable_pipestat(dev_priv, 0, - PIPE_HOTPLUG_INTERRUPT_ENABLE | - PIPE_HOTPLUG_TV_INTERRUPT_ENABLE); - spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags); + if (connector->polled & DRM_CONNECTOR_POLL_HPD) { + spin_lock_irqsave(&dev_priv->irq_lock, irqflags); + i915_disable_pipestat(dev_priv, 0, + PIPE_HOTPLUG_INTERRUPT_ENABLE | + PIPE_HOTPLUG_TV_INTERRUPT_ENABLE); + spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags); + } save_tv_dac = tv_dac = I915_READ(TV_DAC); save_tv_ctl = tv_ctl = I915_READ(TV_CTL); @@ -1302,11 +1305,13 @@ intel_tv_detect_type (struct intel_tv *intel_tv) I915_WRITE(TV_CTL, save_tv_ctl); /* Restore interrupt config */ - spin_lock_irqsave(&dev_priv->irq_lock, irqflags); - i915_enable_pipestat(dev_priv, 0, - PIPE_HOTPLUG_INTERRUPT_ENABLE | - PIPE_HOTPLUG_TV_INTERRUPT_ENABLE); - spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags); + if (connector->polled & DRM_CONNECTOR_POLL_HPD) { + spin_lock_irqsave(&dev_priv->irq_lock, irqflags); + i915_enable_pipestat(dev_priv, 0, + PIPE_HOTPLUG_INTERRUPT_ENABLE | + PIPE_HOTPLUG_TV_INTERRUPT_ENABLE); + spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags); + } return type; } @@ -1356,7 +1361,7 @@ intel_tv_detect(struct drm_connector *connector, bool force) drm_mode_set_crtcinfo(&mode, CRTC_INTERLACE_HALVE_V); if (intel_tv->base.base.crtc && intel_tv->base.base.crtc->enabled) { - type = intel_tv_detect_type(intel_tv); + type = intel_tv_detect_type(intel_tv, connector); } else if (force) { struct drm_crtc *crtc; int dpms_mode; @@ -1364,7 +1369,7 @@ intel_tv_detect(struct drm_connector *connector, bool force) crtc = intel_get_load_detect_pipe(&intel_tv->base, connector, &mode, &dpms_mode); if (crtc) { - type = intel_tv_detect_type(intel_tv); + type = intel_tv_detect_type(intel_tv, connector); intel_release_load_detect_pipe(&intel_tv->base, connector, dpms_mode); } else @@ -1658,6 +1663,18 @@ intel_tv_init(struct drm_device *dev) intel_encoder = &intel_tv->base; connector = &intel_connector->base; + /* The documentation, for the older chipsets at least, recommend + * using a polling method rather than hotplug detection for TVs. + * This is because in order to perform the hotplug detection, the PLLs + * for the TV must be kept alive increasing power drain and starving + * bandwidth from other encoders. Notably for instance, it causes + * pipe underruns on Crestline when this encoder is supposedly idle. + * + * More recent chipsets favour HDMI rather than integrated S-Video. + */ + connector->polled = + DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT; + drm_connector_init(dev, connector, &intel_tv_connector_funcs, DRM_MODE_CONNECTOR_SVIDEO); -- GitLab