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Commit 9625604c authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/irq: Add drm_crtc_vblank_reset 



At driver load we need to tell the vblank code about the state of the
pipes, so that the logic around reject vblank_get when the pipe is off
works correctly.

Thus far i915 used drm_vblank_off, but one of the side-effects of it
is that it also saves the vblank counter. And for that it calls down
into the ->get_vblank_counter hook. Which isn't really a good idea
when the pipe is off for a few reasons:
- With runtime pm the register might not respond.
- If the pipe is off some datastructures might not be around or
  unitialized.

The later is what blew up on gen3: We look at intel_crtc->config to
compute the vblank counter, and for a disabled pipe at boot-up that's
just not there. Thus far this was papered over by a check for
intel_crtc->active, but I want to get rid of that (since it's fairly
race, vblank hooks are called from all kinds of places).

So prep for that by adding a _reset functions which only does what we
really need to be done at driver load: Mark the vblank pipe as off,
but don't do any vblank counter saving or event flushing - neither of
that is required.

v2: Clarify the code flow slightly as suggested by Ville.

v3: Fix kerneldoc spelling, spotted by Laurent.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com> (v2)
Acked-by: default avatarDave Airlie <airlied@redhat.com>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
parent d4495cba

drivers/gpu/drm/drm_irq.c

+32 −0
Original line number Diff line number Diff line
@@ -1225,6 +1225,38 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc) 
}

EXPORT_SYMBOL(drm_crtc_vblank_off);



/**

 * drm_crtc_vblank_reset - reset vblank state to off on a CRTC

 * @crtc: CRTC in question

 *

 * Drivers can use this function to reset the vblank state to off at load time.

 * Drivers should use this together with the drm_crtc_vblank_off() and

 * drm_crtc_vblank_on() functions. The difference compared to

 * drm_crtc_vblank_off() is that this function doesn't save the vblank counter

 * and hence doesn't need to call any driver hooks.

 */

void drm_crtc_vblank_reset(struct drm_crtc *drm_crtc)

{

	struct drm_device *dev = drm_crtc->dev;

	unsigned long irqflags;

	int crtc = drm_crtc_index(drm_crtc);

	struct drm_vblank_crtc *vblank = &dev->vblank[crtc];



	spin_lock_irqsave(&dev->vbl_lock, irqflags);

	/*

	 * Prevent subsequent drm_vblank_get() from enabling the vblank

	 * interrupt by bumping the refcount.

	 */

	if (!vblank->inmodeset) {

		atomic_inc(&vblank->refcount);

		vblank->inmodeset = 1;

	}

	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);



	WARN_ON(!list_empty(&dev->vblank_event_list));

}

EXPORT_SYMBOL(drm_crtc_vblank_reset);



/**

 * drm_vblank_on - enable vblank events on a CRTC

 * @dev: DRM device

drivers/gpu/drm/i915/intel_display.c

+3 −3
Original line number Diff line number Diff line
@@ -13316,11 +13316,11 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc) 
	I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);



	/* restore vblank interrupts to correct state */

	drm_crtc_vblank_reset(&crtc->base);

	if (crtc->active) {

		update_scanline_offset(crtc);

		drm_vblank_on(dev, crtc->pipe);

	} else

		drm_vblank_off(dev, crtc->pipe);

		drm_crtc_vblank_on(&crtc->base);

	}



	/* We need to sanitize the plane -> pipe mapping first because this will

	 * disable the crtc (and hence change the state) if it is wrong. Note

include/drm/drmP.h

+1 −0
Original line number Diff line number Diff line
@@ -922,6 +922,7 @@ extern void drm_crtc_wait_one_vblank(struct drm_crtc *crtc); 
extern void drm_vblank_off(struct drm_device *dev, int crtc);

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

extern void drm_crtc_vblank_off(struct drm_crtc *crtc);

extern void drm_crtc_vblank_reset(struct drm_crtc *crtc);

extern void drm_crtc_vblank_on(struct drm_crtc *crtc);

extern void drm_vblank_cleanup(struct drm_device *dev);