Re: [PATCH v3 06/10] drm: rcar-du: Handle CRTC configuration from commit tail handler

[Ulrich Hecht <uli@fpond.eu>]

> On June 17, 2019 at 11:09 PM Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> wrote:
> 
> 
> From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> 
> The CRTC mode setting and routing configuration are performed at the
> earliest of atomic enable and atomic begin, to ensure that a valid
> configuration is applied to the hardware before the CRTC gets enabled
> and before planes are setup (the latter being required in particular by
> the VSP). This requires the rcar_du_crtc structure to track the CRTC
> enabled state.
> 
> Simplify the code and remove the manual state tracking by moving CRTC
> setup to a new rcar_du_crtc_atomic_modeset() function, called directly
> from the commit tail handler. The function iterates over all CRTCs in
> the state transaction and performs CRTC mode setting, routing
> configuration and VSP configuration.
> 
> drm_crtc_vblank_on() has to be called from the atomic begin handler, to
> ensure that vertical blanking reporting is enabled before the call to
> drm_crtc_vblank_get() in the atomic flush handler. As the
> drm_crtc_vblank_on() and drm_crtc_vblank_off() calls don't need to be
> balanced this is not an issue. A balanced alternative would have been to
> call drm_crtc_vblank_on() and drm_crtc_vblank_off() from the CRTC exit
> and enter standby handlers respectively, but
> drm_atomic_helper_commit_modeset_disables() complains if
> drm_crtc_vblank_off() hasn't been called by the atomic disable handler.
> 
> As a result, the vsp1_du_atomic_flush() operation can be called with the
> DRM pipeline disabled. Correct operation has been ensured by "media:
> vsp1: drm: Don't configure hardware when the pipeline is disabled".
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> ---
> Changes since v2:
> 
> - Deconstruct rcar_du_crtc_setup() completely
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 89 +++++++++++---------------
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.h |  4 +-
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c  |  1 +
>  3 files changed, 42 insertions(+), 52 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index 23f4bdef0e3a..d11a474f6f72 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -478,22 +478,6 @@ static void rcar_du_crtc_wait_page_flip(struct rcar_du_crtc *rcrtc)
>   * Start/Stop and Suspend/Resume
>   */
>  
> -static void rcar_du_crtc_setup(struct rcar_du_crtc *rcrtc)
> -{
> -	/* Configure display timings and output routing */
> -	rcar_du_crtc_set_display_timing(rcrtc);
> -	rcar_du_group_set_routing(rcrtc->group);
> -
> -	/* Enable the VSP compositor. */
> -	if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE)) {
> -		rcar_du_vsp_modeset(rcrtc);
> -		rcar_du_vsp_enable(rcrtc);
> -	}
> -
> -	/* Turn vertical blanking interrupt reporting on. */
> -	drm_crtc_vblank_on(&rcrtc->crtc);
> -}
> -
>  static int rcar_du_crtc_exit_standby(struct rcar_du_crtc *rcrtc)
>  {
>  	int ret;
> @@ -534,24 +518,6 @@ static void rcar_du_crtc_enter_standby(struct rcar_du_crtc *rcrtc)
>  	clk_disable_unprepare(rcrtc->clock);
>  }
>  
> -static void rcar_du_crtc_get(struct rcar_du_crtc *rcrtc)
> -{
> -	/*
> -	 * Guard against double-get, as the function is called from both the
> -	 * .atomic_enable() and .atomic_begin() handlers.
> -	 */
> -	if (rcrtc->initialized)
> -		return;
> -
> -	rcar_du_crtc_setup(rcrtc);
> -	rcrtc->initialized = true;
> -}
> -
> -static void rcar_du_crtc_put(struct rcar_du_crtc *rcrtc)
> -{
> -	rcrtc->initialized = false;
> -}
> -
>  static void rcar_du_crtc_start(struct rcar_du_crtc *rcrtc)
>  {
>  	bool interlaced;
> @@ -716,6 +682,40 @@ int rcar_du_crtc_atomic_enter_standby(struct drm_device *dev,
>  	return 0;
>  }
>  
> +/*
> + * Configure the mode for all CRTCs that require it. For now we only handle mode
> + * set on the VSP, CRTC configuration will be handled later.
> + */
> +int rcar_du_crtc_atomic_modeset(struct drm_device *dev,
> +				struct drm_atomic_state *state)
> +{
> +	struct drm_crtc_state *crtc_state;
> +	struct drm_crtc *crtc;
> +	unsigned int i;
> +
> +	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
> +		struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
> +
> +		/*
> +		 * Skip commits that don't change the mode. We manually skip
> +		 * inactive CRTCs as disabling a CRTC is considered as a mode
> +		 * set by drm_atomic_crtc_needs_modeset().
> +		 */
> +		if (!drm_atomic_crtc_needs_modeset(crtc_state) ||
> +		    !crtc_state->active)
> +			continue;
> +
> +		/* Configure display timings and output routing. */
> +		rcar_du_crtc_set_display_timing(rcrtc);
> +		rcar_du_group_set_routing(rcrtc->group);
> +
> +		if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
> +			rcar_du_vsp_modeset(rcrtc);
> +	}
> +
> +	return 0;
> +}
> +
>  static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
>  				       struct drm_crtc_state *old_state)
>  {
> @@ -723,8 +723,6 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
>  	struct rcar_du_crtc_state *rstate = to_rcar_crtc_state(crtc->state);
>  	struct rcar_du_device *rcdu = rcrtc->dev;
>  
> -	rcar_du_crtc_get(rcrtc);
> -
>  	/*
>  	 * On D3/E3 the dot clock is provided by the LVDS encoder attached to
>  	 * the DU channel. We need to enable its clock output explicitly if
> @@ -741,6 +739,9 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
>  				     mode->clock * 1000);
>  	}
>  
> +	if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
> +		rcar_du_vsp_enable(rcrtc);
> +
>  	rcar_du_crtc_start(rcrtc);
>  }
>  
> @@ -752,7 +753,6 @@ static void rcar_du_crtc_atomic_disable(struct drm_crtc *crtc,
>  	struct rcar_du_device *rcdu = rcrtc->dev;
>  
>  	rcar_du_crtc_stop(rcrtc);
> -	rcar_du_crtc_put(rcrtc);
>  
>  	if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index) &&
>  	    rstate->outputs == BIT(RCAR_DU_OUTPUT_DPAD0)) {
> @@ -781,19 +781,8 @@ static void rcar_du_crtc_atomic_begin(struct drm_crtc *crtc,
>  
>  	WARN_ON(!crtc->state->enable);
>  
> -	/*
> -	 * If a mode set is in progress we can be called with the CRTC disabled.
> -	 * We thus need to first get and setup the CRTC in order to configure
> -	 * planes. We must *not* put the CRTC in .atomic_flush(), as it must be
> -	 * kept awake until the .atomic_enable() call that will follow. The get
> -	 * operation in .atomic_enable() will in that case be a no-op, and the
> -	 * CRTC will be put later in .atomic_disable().
> -	 *
> -	 * If a mode set is not in progress the CRTC is enabled, and the
> -	 * following get call will be a no-op. There is thus no need to balance
> -	 * it in .atomic_flush() either.
> -	 */
> -	rcar_du_crtc_get(rcrtc);
> +	/* Turn vertical blanking interrupt reporting on. */
> +	drm_crtc_vblank_on(&rcrtc->crtc);
>  
>  	if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
>  		rcar_du_vsp_atomic_begin(rcrtc);
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> index 3ce7610793b2..61d79aa7c8e8 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> @@ -30,7 +30,6 @@ struct rcar_du_vsp;
>   * @extclock: external pixel dot clock (optional)
>   * @mmio_offset: offset of the CRTC registers in the DU MMIO block
>   * @index: CRTC hardware index
> - * @initialized: whether the CRTC has been initialized and clocks enabled
>   * @dsysr: cached value of the DSYSR register
>   * @vblank_enable: whether vblank events are enabled on this CRTC
>   * @event: event to post when the pending page flip completes
> @@ -51,7 +50,6 @@ struct rcar_du_crtc {
>  	struct clk *extclock;
>  	unsigned int mmio_offset;
>  	unsigned int index;
> -	bool initialized;
>  
>  	u32 dsysr;
>  
> @@ -111,6 +109,8 @@ int rcar_du_crtc_atomic_exit_standby(struct drm_device *dev,
>  				     struct drm_atomic_state *state);
>  int rcar_du_crtc_atomic_enter_standby(struct drm_device *dev,
>  				      struct drm_atomic_state *state);
> +int rcar_du_crtc_atomic_modeset(struct drm_device *dev,
> +				struct drm_atomic_state *state);
>  
>  void rcar_du_crtc_dsysr_clr_set(struct rcar_du_crtc *rcrtc, u32 clr, u32 set);
>  
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> index 59680de271cc..144c0c1b1591 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -412,6 +412,7 @@ static void rcar_du_atomic_commit_tail(struct drm_atomic_state *old_state)
>  	rcar_du_crtc_atomic_exit_standby(dev, old_state);
>  
>  	drm_atomic_helper_commit_modeset_disables(dev, old_state);
> +	rcar_du_crtc_atomic_modeset(dev, old_state);
>  	drm_atomic_helper_commit_planes(dev, old_state,
>  					DRM_PLANE_COMMIT_ACTIVE_ONLY);
>  	drm_atomic_helper_commit_modeset_enables(dev, old_state);
> -- 
> Regards,
> 
> Laurent Pinchart
>

Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>

CU
Uli