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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 <hughd@google.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[This is a candidate for stable, but needs minor porting to 2.6.37]
This commit is contained in:
Chris Wilson 2011-02-10 10:05:35 +00:00
Родитель 1aad7ac045
Коммит 8102e126c0
1 изменённых файлов: 30 добавлений и 13 удалений
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23
drivers/gpu/drm/i915/intel_tv.c
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@ -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 */
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 */
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);