Re: [PATCH v3 01/23] drm: add vblank hooks to struct drm_crtc_funcs

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Shawn,

Thank you for the patch.

On Tuesday 07 Feb 2017 17:16:13 Shawn Guo wrote:
> From: Shawn Guo <shawn.guo@linaro.org>
> 
> The vblank is mostly CRTC specific and implemented as part of CRTC
> driver.  Let's keep the vblank hooks struct drm_driver for legacy
> drivers, and add corresponding hooks in struct drm_crtc_funcs.  These
> hooks take struct drm_crtc pointer as argument, and will be called by
> core vblank handling code for DRIVER_MODESET drivers.
> 
> The new hooks get plugged into core by adding wrapper functions for
> vblank handling code.  The .get_vblank_counter hook is effectively
> optional, as we provide drm_vblank_no_hw_counter() as the default
> fallback in the wrapper function.
> 
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/gpu/drm/drm_irq.c | 53 ++++++++++++++++++++++++++++++++++++++------
>  include/drm/drm_crtc.h    | 44 +++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_drv.h     |  9 ++++++++
>  3 files changed, 100 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index e06cf11ebb4a..646b3e57b9ad 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -89,6 +89,21 @@ static void store_vblank(struct drm_device *dev, unsigned
> int pipe, write_sequnlock(&vblank->seqlock);
>  }
> 
> +static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe)
> +{
> +	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
> +
> +		if (crtc->funcs->get_vblank_counter)
> +			return crtc->funcs->get_vblank_counter(crtc);
> +	}
> +
> +	if (dev->driver->get_vblank_counter)
> +		return dev->driver->get_vblank_counter(dev, pipe);
> +
> +	return drm_vblank_no_hw_counter(dev, pipe);
> +}
> +
>  /*
>   * Reset the stored timestamp for the current vblank count to correspond
>   * to the last vblank occurred.
> @@ -112,9 +127,9 @@ static void drm_reset_vblank_timestamp(struct drm_device
> *dev, unsigned int pipe * when drm_vblank_enable() applies the diff
>  	 */
>  	do {
> -		cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
> +		cur_vblank = __get_vblank_counter(dev, pipe);
>  		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, 0);
> -	} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) &&
> --count > 0); +	} while (cur_vblank != __get_vblank_counter(dev, pipe) 
&&
> --count > 0);
> 
>  	/*
>  	 * Only reinitialize corresponding vblank timestamp if high-precision
> query @@ -168,9 +183,9 @@ static void drm_update_vblank_count(struct
> drm_device *dev, unsigned int pipe, * corresponding vblank timestamp.
>  	 */
>  	do {
> -		cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
> +		cur_vblank = __get_vblank_counter(dev, pipe);
>  		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);
> -	} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) &&
> --count > 0); +	} while (cur_vblank != __get_vblank_counter(dev, pipe) 
&&
> --count > 0);
> 
>  	if (dev->max_vblank_count != 0) {
>  		/* trust the hw counter when it's around */
> @@ -275,6 +290,20 @@ u32 drm_accurate_vblank_count(struct drm_crtc *crtc)
>  }
>  EXPORT_SYMBOL(drm_accurate_vblank_count);
> 
> +static void __disable_vblank(struct drm_device *dev, unsigned int pipe)
> +{
> +	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
> +
> +		if (crtc->funcs->disable_vblank) {
> +			crtc->funcs->disable_vblank(crtc);
> +			return;
> +		}
> +	}
> +
> +	dev->driver->disable_vblank(dev, pipe);
> +}
> +
>  /*
>   * Disable vblank irq's on crtc, make sure that last vblank count
>   * of hardware and corresponding consistent software vblank counter
> @@ -298,7 +327,7 @@ static void vblank_disable_and_save(struct drm_device
> *dev, unsigned int pipe) * hardware potentially runtime suspended.
>  	 */
>  	if (vblank->enabled) {
> -		dev->driver->disable_vblank(dev, pipe);
> +		__disable_vblank(dev, pipe);
>  		vblank->enabled = false;
>  	}
> 
> @@ -1027,6 +1056,18 @@ void drm_crtc_send_vblank_event(struct drm_crtc
> *crtc, }
>  EXPORT_SYMBOL(drm_crtc_send_vblank_event);
> 
> +static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
> +{
> +	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
> +
> +		if (crtc->funcs->enable_vblank)
> +			return crtc->funcs->enable_vblank(crtc);
> +	}
> +
> +	return dev->driver->enable_vblank(dev, pipe);
> +}
> +
>  /**
>   * drm_vblank_enable - enable the vblank interrupt on a CRTC
>   * @dev: DRM device
> @@ -1052,7 +1093,7 @@ static int drm_vblank_enable(struct drm_device *dev,
> unsigned int pipe) * timestamps. Filtercode in drm_handle_vblank() will
>  		 * prevent double-accounting of same vblank interval.
>  		 */
> -		ret = dev->driver->enable_vblank(dev, pipe);
> +		ret = __enable_vblank(dev, pipe);
>  		DRM_DEBUG("enabling vblank on crtc %u, ret: %d\n", pipe, ret);
>  		if (ret)
>  			atomic_dec(&vblank->refcount);
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 8f0b195e4a59..4323acefa596 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -601,6 +601,50 @@ struct drm_crtc_funcs {
>  	 */
>  	void (*atomic_print_state)(struct drm_printer *p,
>  				   const struct drm_crtc_state *state);
> +
> +	/**
> +	 * @get_vblank_counter:
> +	 *
> +	 * Driver callback for fetching a raw hardware vblank counter for the
> +	 * CRTC. It's meant to be used by new drivers as the replacement of
> +	 * &drm_driver.get_vblank_counter hook.
> +	 *
> +	 * This callback is optional. 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.
> +	 *
> +	 * Returns:
> +	 *
> +	 * Raw vblank counter value.
> +	 */
> +	u32 (*get_vblank_counter)(struct drm_crtc *crtc);
> +
> +	/**
> +	 * @enable_vblank:
> +	 *
> +	 * Enable vblank interrupts for the CRTC. It's meant to be used by
> +	 * new drivers as the replacement of &drm_driver.enable_vblank hook.
> +	 *
> +	 * Returns:
> +	 *
> +	 * Zero on success, appropriate errno if the vblank interrupt cannot
> +	 * be enabled.
> +	 */
> +	int (*enable_vblank)(struct drm_crtc *crtc);
> +
> +	/**
> +	 * @disable_vblank:
> +	 *
> +	 * Disable vblank interrupts for the CRTC. It's meant to be used by
> +	 * new drivers as the replacement of &drm_driver.disable_vblank hook.
> +	 */
> +	void (*disable_vblank)(struct drm_crtc *crtc);
>  };
> 
>  /**
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index f2c0040ddc3a..40ae89106594 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -130,6 +130,9 @@ struct drm_driver {
>  	 * 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.
> @@ -142,6 +145,9 @@ struct drm_driver {
>  	 * 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
> @@ -154,6 +160,9 @@ struct drm_driver {
>  	 *
>  	 * 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);

-- 
Regards,

Laurent Pinchart

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