Re: [PATCH 23/23] drm: Cleanup VBLANK callbacks in struct drm_driver

[Daniel Vetter <daniel@ffwll.ch>]

On Sun, Jan 12, 2020 at 11:53:12PM +0100, Daniel Vetter wrote:
> On Fri, Jan 10, 2020 at 10:21:27AM +0100, Thomas Zimmermann wrote:
> > All non-legacy users of VBLANK functions in struct drm_driver have been
> > converted to use the respective interfaces in struct drm_crtc_funcs. The
> > remaining users of VBLANK callbacks in struct drm_driver are legacy drivers
> > with userspace modesetting.
> > 
> > There are no users left of get_vblank_timestamp(), so the callback is
> > being removed. The other VBLANK callbacks are being moved to the legacy
> > section at the end of struct drm_driver.
> > 
> > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> I think sprinkling some WARN_ON (in drm_dev_register or wherever) if new
> drivers try to use the legacy hooks would be really nice. Experience says
> someone is going to copypaste this stuff around forever otherwise.

I meant to add: As a follow-up patch.
-Daniel

> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> > ---
> >  drivers/gpu/drm/drm_vblank.c |  39 +++++---------
> >  include/drm/drm_drv.h        | 101 ++---------------------------------
> >  2 files changed, 17 insertions(+), 123 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> > index 7cf436a4b908..ceff68474d4d 100644
> > --- a/drivers/gpu/drm/drm_vblank.c
> > +++ b/drivers/gpu/drm/drm_vblank.c
> > @@ -138,10 +138,9 @@ static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe)
> >  
> >  		if (crtc->funcs->get_vblank_counter)
> >  			return crtc->funcs->get_vblank_counter(crtc);
> > -	}
> > -
> > -	if (dev->driver->get_vblank_counter)
> > +	} else if (dev->driver->get_vblank_counter) {
> >  		return dev->driver->get_vblank_counter(dev, pipe);
> > +	}
> >  
> >  	return drm_vblank_no_hw_counter(dev, pipe);
> >  }
> > @@ -334,8 +333,7 @@ u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc)
> >  	unsigned long flags;
> >  
> >  	WARN_ONCE(drm_debug_enabled(DRM_UT_VBL) &&
> > -		  !crtc->funcs->get_vblank_timestamp &&
> > -		  !dev->driver->get_vblank_timestamp,
> > +		  !crtc->funcs->get_vblank_timestamp,
> >  		  "This function requires support for accurate vblank timestamps.");
> >  
> >  	spin_lock_irqsave(&dev->vblank_time_lock, flags);
> > @@ -357,13 +355,11 @@ static void __disable_vblank(struct drm_device *dev, unsigned int pipe)
> >  		if (WARN_ON(!crtc))
> >  			return;
> >  
> > -		if (crtc->funcs->disable_vblank) {
> > +		if (crtc->funcs->disable_vblank)
> >  			crtc->funcs->disable_vblank(crtc);
> > -			return;
> > -		}
> > +	} else {
> > +		dev->driver->disable_vblank(dev, pipe);
> >  	}
> > -
> > -	dev->driver->disable_vblank(dev, pipe);
> >  }
> >  
> >  /*
> > @@ -791,9 +787,6 @@ drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
> >  
> >  		ret = crtc->funcs->get_vblank_timestamp(crtc, &max_error,
> >  							tvblank, in_vblank_irq);
> > -	} else if (dev->driver->get_vblank_timestamp && (max_error > 0)) {
> > -		ret = dev->driver->get_vblank_timestamp(dev, pipe, &max_error,
> > -							tvblank, in_vblank_irq);
> >  	}
> >  
> >  	/* GPU high precision timestamp query unsupported or failed.
> > @@ -1016,9 +1009,11 @@ static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
> >  
> >  		if (crtc->funcs->enable_vblank)
> >  			return crtc->funcs->enable_vblank(crtc);
> > +	} else if (dev->driver->enable_vblank) {
> > +		return dev->driver->enable_vblank(dev, pipe);
> >  	}
> >  
> > -	return dev->driver->enable_vblank(dev, pipe);
> > +	return -EINVAL;
> >  }
> >  
> >  static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
> > @@ -1109,13 +1104,10 @@ static bool __vblank_disable_immediate(struct drm_device *dev, unsigned int pipe
> >  		return false;
> >  
> >  	crtc = drm_crtc_from_index(dev, pipe);
> > -	if (crtc && crtc->funcs->get_vblank_timestamp)
> > -		return true;
> > -
> > -	if (dev->driver->get_vblank_timestamp)
> > -		return true;
> > +	if (!crtc || !crtc->funcs->get_vblank_timestamp)
> > +		return false;
> >  
> > -	return false;
> > +	return true;
> >  }
> >  
> >  static void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
> > @@ -1798,7 +1790,6 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
> >  	struct drm_pending_vblank_event *e, *t;
> >  	ktime_t now;
> >  	u64 seq;
> > -	bool high_prec;
> >  
> >  	assert_spin_locked(&dev->event_lock);
> >  
> > @@ -1818,10 +1809,8 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
> >  		send_vblank_event(dev, e, seq, now);
> >  	}
> >  
> > -	high_prec = crtc->funcs->get_vblank_timestamp ||
> > -		    dev->driver->get_vblank_timestamp;
> > -
> > -	trace_drm_vblank_event(pipe, seq, now, high_prec);
> > +	trace_drm_vblank_event(pipe, seq, now,
> > +			       crtc->funcs->get_vblank_timestamp != NULL);
> >  }
> >  
> >  /**
> > diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> > index b704e252f3b2..e290b3aca6eb 100644
> > --- a/include/drm/drm_drv.h
> > +++ b/include/drm/drm_drv.h
> > @@ -268,104 +268,6 @@ struct drm_driver {
> >  	 */
> >  	void (*release) (struct drm_device *);
> >  
> > -	/**
> > -	 * @get_vblank_counter:
> > -	 *
> > -	 * Driver callback for fetching a raw hardware vblank counter for the
> > -	 * CRTC specified with the pipe argument.  If a device doesn't have a
> > -	 * hardware counter, the driver can simply leave the hook as NULL.
> > -	 * The DRM core will account for missed vblank events while interrupts
> > -	 * where disabled based on system timestamps.
> > -	 *
> > -	 * Wraparound handling and loss of events due to modesetting is dealt
> > -	 * with in the DRM core code, as long as drivers call
> > -	 * drm_crtc_vblank_off() and drm_crtc_vblank_on() when disabling or
> > -	 * enabling a CRTC.
> > -	 *
> > -	 * This is deprecated and should not be used by new drivers.
> > -	 * Use &drm_crtc_funcs.get_vblank_counter instead.
> > -	 *
> > -	 * Returns:
> > -	 *
> > -	 * Raw vblank counter value.
> > -	 */
> > -	u32 (*get_vblank_counter) (struct drm_device *dev, unsigned int pipe);
> > -
> > -	/**
> > -	 * @enable_vblank:
> > -	 *
> > -	 * Enable vblank interrupts for the CRTC specified with the pipe
> > -	 * argument.
> > -	 *
> > -	 * This is deprecated and should not be used by new drivers.
> > -	 * Use &drm_crtc_funcs.enable_vblank instead.
> > -	 *
> > -	 * Returns:
> > -	 *
> > -	 * Zero on success, appropriate errno if the given @crtc's vblank
> > -	 * interrupt cannot be enabled.
> > -	 */
> > -	int (*enable_vblank) (struct drm_device *dev, unsigned int pipe);
> > -
> > -	/**
> > -	 * @disable_vblank:
> > -	 *
> > -	 * Disable vblank interrupts for the CRTC specified with the pipe
> > -	 * argument.
> > -	 *
> > -	 * This is deprecated and should not be used by new drivers.
> > -	 * Use &drm_crtc_funcs.disable_vblank instead.
> > -	 */
> > -	void (*disable_vblank) (struct drm_device *dev, unsigned int pipe);
> > -
> > -	/**
> > -	 * @get_vblank_timestamp:
> > -	 *
> > -	 * Called by drm_get_last_vbltimestamp(). Should return a precise
> > -	 * timestamp when the most recent VBLANK interval ended or will end.
> > -	 *
> > -	 * Specifically, the timestamp in @vblank_time should correspond as
> > -	 * closely as possible to the time when the first video scanline of
> > -	 * the video frame after the end of VBLANK will start scanning out,
> > -	 * the time immediately after end of the VBLANK interval. If the
> > -	 * @crtc is currently inside VBLANK, this will be a time in the future.
> > -	 * If the @crtc is currently scanning out a frame, this will be the
> > -	 * past start time of the current scanout. This is meant to adhere
> > -	 * to the OpenML OML_sync_control extension specification.
> > -	 *
> > -	 * Paramters:
> > -	 *
> > -	 * dev:
> > -	 *     dev DRM device handle.
> > -	 * pipe:
> > -	 *     crtc for which timestamp should be returned.
> > -	 * max_error:
> > -	 *     Maximum allowable timestamp error in nanoseconds.
> > -	 *     Implementation should strive to provide timestamp
> > -	 *     with an error of at most max_error nanoseconds.
> > -	 *     Returns true upper bound on error for timestamp.
> > -	 * vblank_time:
> > -	 *     Target location for returned vblank timestamp.
> > -	 * in_vblank_irq:
> > -	 *     True when called from drm_crtc_handle_vblank().  Some drivers
> > -	 *     need to apply some workarounds for gpu-specific vblank irq quirks
> > -	 *     if flag is set.
> > -	 *
> > -	 * Returns:
> > -	 *
> > -	 * True on success, false on failure, which means the core should
> > -	 * fallback to a simple timestamp taken in drm_crtc_handle_vblank().
> > -	 *
> > -	 * FIXME:
> > -	 *
> > -	 * We should move this hook to &struct drm_crtc_funcs like all the other
> > -	 * vblank hooks.
> > -	 */
> > -	bool (*get_vblank_timestamp) (struct drm_device *dev, unsigned int pipe,
> > -				     int *max_error,
> > -				     ktime_t *vblank_time,
> > -				     bool in_vblank_irq);
> > -
> >  	/**
> >  	 * @irq_handler:
> >  	 *
> > @@ -720,6 +622,9 @@ struct drm_driver {
> >  	int (*dma_ioctl) (struct drm_device *dev, void *data, struct drm_file *file_priv);
> >  	int (*dma_quiescent) (struct drm_device *);
> >  	int (*context_dtor) (struct drm_device *dev, int context);
> > +	u32 (*get_vblank_counter)(struct drm_device *dev, unsigned int pipe);
> > +	int (*enable_vblank)(struct drm_device *dev, unsigned int pipe);
> > +	void (*disable_vblank)(struct drm_device *dev, unsigned int pipe);
> >  	int dev_priv_size;
> >  };
> >  
> > -- 
> > 2.24.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch