Commit 778c9026 authored by Li Peng's avatar Li Peng Committed by Eric Anholt
Browse files

drm/i915: Fix sync to vblank when VGA output is turned off 



In current vblank-wait implementation, if we turn off VGA output,
drm_wait_vblank will still wait on the disabled pipe until timeout,
because vblank on the pipe is assumed be enabled. This would cause
slow system response on some system such as moblin.

This patch resolve the issue by adding a drm helper function
drm_vblank_off which explicitly clear vblank_enabled[crtc], wake up
any waiting queue and save last vblank counter before turning off
crtc. It also slightly change drm_vblank_get to ensure that we will
will return immediately if trying to wait on a disabled pipe.

Signed-off-by: default avatarLi Peng <peng.li@intel.com>
Reviewed-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
[anholt: hand-applied for conflicts with overlay changes]
Signed-off-by: default avatarEric Anholt <eric@anholt.net>
parent 27dfaf4f

drivers/gpu/drm/drm_irq.c

+26 −8
Original line number Diff line number Diff line
@@ -429,8 +429,8 @@ int drm_vblank_get(struct drm_device *dev, int crtc) 


	spin_lock_irqsave(&dev->vbl_lock, irqflags);

	/* Going from 0->1 means we have to enable interrupts again */

	if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1 &&

	    !dev->vblank_enabled[crtc]) {

	if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {

		if (!dev->vblank_enabled[crtc]) {

			ret = dev->driver->enable_vblank(dev, crtc);

			DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n", crtc, ret);

			if (ret)
@@ -440,6 +440,12 @@ int drm_vblank_get(struct drm_device *dev, int crtc) 
				drm_update_vblank_count(dev, crtc);

			}

		}

	} else {

		if (!dev->vblank_enabled[crtc]) {

			atomic_dec(&dev->vblank_refcount[crtc]);

			ret = -EINVAL;

		}

	}

	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);



	return ret;
@@ -464,6 +470,18 @@ void drm_vblank_put(struct drm_device *dev, int crtc) 
}

EXPORT_SYMBOL(drm_vblank_put);



void drm_vblank_off(struct drm_device *dev, int crtc)

{

	unsigned long irqflags;



	spin_lock_irqsave(&dev->vbl_lock, irqflags);

	DRM_WAKEUP(&dev->vbl_queue[crtc]);

	dev->vblank_enabled[crtc] = 0;

	dev->last_vblank[crtc] = dev->driver->get_vblank_counter(dev, crtc);

	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

}

EXPORT_SYMBOL(drm_vblank_off);



/**

 * drm_vblank_pre_modeset - account for vblanks across mode sets

 * @dev: DRM device

drivers/gpu/drm/i915/intel_display.c

+1 −0
Original line number Diff line number Diff line
@@ -1924,6 +1924,7 @@ static void i9xx_crtc_dpms(struct drm_crtc *crtc, int mode) 


		/* Give the overlay scaler a chance to disable if it's on this pipe */

		intel_crtc_dpms_overlay(intel_crtc, false);

		drm_vblank_off(dev, pipe);



		if (dev_priv->cfb_plane == plane &&

		    dev_priv->display.disable_fbc)

include/drm/drmP.h

+1 −0
Original line number Diff line number Diff line
@@ -1288,6 +1288,7 @@ extern u32 drm_vblank_count(struct drm_device *dev, int crtc); 
extern void drm_handle_vblank(struct drm_device *dev, int crtc);

extern int drm_vblank_get(struct drm_device *dev, int crtc);

extern void drm_vblank_put(struct drm_device *dev, int crtc);

extern void drm_vblank_off(struct drm_device *dev, int crtc);

extern void drm_vblank_cleanup(struct drm_device *dev);

/* Modesetting support */

extern void drm_vblank_pre_modeset(struct drm_device *dev, int crtc);

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