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

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 12.01.20 um 23:53 schrieb Daniel Vetter:
> 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've been thinking about moving these fields to separate structures, say
struct drm_legacy_device and struct drm_legacy_driver. Those would be
allocated for legacy drivers and KMS drivers would never see them
(except for their forward declaration).

Best regards
Thomas

> 
> 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
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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