Re: [PATCH] drm/atmel: Use drm_atomic_helper_commit

[Sam Ravnborg <sam@ravnborg.org>]

Hi Daniel.

On Tue, Jul 07, 2020 at 11:31:37PM +0200, Daniel Vetter wrote:
> One of these drivers that predates the nonblocking support in helpers,
> and hand-rolled its own thing. Entirely not anything specific here, we
> can just delete it all and replace it with the helper version.
> 
> Could also perhaps use the drm_mode_config_helper_suspend/resume
> stuff, for another few lines deleted. But I'm not looking at that
> stuff, I'm just going through all the atomic commit functions and make
> sure they have properly annotated dma-fence critical sections
> everywhere.
> 
> v2:
> - Also delete the workqueue (Sam)
> - drop the @commit kerneldoc, I missed that one.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Boris Brezillon <bbrezillon@kernel.org>
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
> Cc: linux-arm-kernel@lists.infradead.org
I did succeed getttign my board operational.
But based on reading the code:
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

I assume you will apply it.

	Sam


> ---
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c | 107 +------------------
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h |   7 --
>  2 files changed, 2 insertions(+), 112 deletions(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> index 871293d1aeeb..03984932d174 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> @@ -557,103 +557,10 @@ static irqreturn_t atmel_hlcdc_dc_irq_handler(int irq, void *data)
>  	return IRQ_HANDLED;
>  }
>  
> -struct atmel_hlcdc_dc_commit {
> -	struct work_struct work;
> -	struct drm_device *dev;
> -	struct drm_atomic_state *state;
> -};
> -
> -static void
> -atmel_hlcdc_dc_atomic_complete(struct atmel_hlcdc_dc_commit *commit)
> -{
> -	struct drm_device *dev = commit->dev;
> -	struct atmel_hlcdc_dc *dc = dev->dev_private;
> -	struct drm_atomic_state *old_state = commit->state;
> -
> -	/* Apply the atomic update. */
> -	drm_atomic_helper_commit_modeset_disables(dev, old_state);
> -	drm_atomic_helper_commit_planes(dev, old_state, 0);
> -	drm_atomic_helper_commit_modeset_enables(dev, old_state);
> -
> -	drm_atomic_helper_wait_for_vblanks(dev, old_state);
> -
> -	drm_atomic_helper_cleanup_planes(dev, old_state);
> -
> -	drm_atomic_state_put(old_state);
> -
> -	/* Complete the commit, wake up any waiter. */
> -	spin_lock(&dc->commit.wait.lock);
> -	dc->commit.pending = false;
> -	wake_up_all_locked(&dc->commit.wait);
> -	spin_unlock(&dc->commit.wait.lock);
> -
> -	kfree(commit);
> -}
> -
> -static void atmel_hlcdc_dc_atomic_work(struct work_struct *work)
> -{
> -	struct atmel_hlcdc_dc_commit *commit =
> -		container_of(work, struct atmel_hlcdc_dc_commit, work);
> -
> -	atmel_hlcdc_dc_atomic_complete(commit);
> -}
> -
> -static int atmel_hlcdc_dc_atomic_commit(struct drm_device *dev,
> -					struct drm_atomic_state *state,
> -					bool async)
> -{
> -	struct atmel_hlcdc_dc *dc = dev->dev_private;
> -	struct atmel_hlcdc_dc_commit *commit;
> -	int ret;
> -
> -	ret = drm_atomic_helper_prepare_planes(dev, state);
> -	if (ret)
> -		return ret;
> -
> -	/* Allocate the commit object. */
> -	commit = kzalloc(sizeof(*commit), GFP_KERNEL);
> -	if (!commit) {
> -		ret = -ENOMEM;
> -		goto error;
> -	}
> -
> -	INIT_WORK(&commit->work, atmel_hlcdc_dc_atomic_work);
> -	commit->dev = dev;
> -	commit->state = state;
> -
> -	spin_lock(&dc->commit.wait.lock);
> -	ret = wait_event_interruptible_locked(dc->commit.wait,
> -					      !dc->commit.pending);
> -	if (ret == 0)
> -		dc->commit.pending = true;
> -	spin_unlock(&dc->commit.wait.lock);
> -
> -	if (ret)
> -		goto err_free;
> -
> -	/* We have our own synchronization through the commit lock. */
> -	BUG_ON(drm_atomic_helper_swap_state(state, false) < 0);
> -
> -	/* Swap state succeeded, this is the point of no return. */
> -	drm_atomic_state_get(state);
> -	if (async)
> -		queue_work(dc->wq, &commit->work);
> -	else
> -		atmel_hlcdc_dc_atomic_complete(commit);
> -
> -	return 0;
> -
> -err_free:
> -	kfree(commit);
> -error:
> -	drm_atomic_helper_cleanup_planes(dev, state);
> -	return ret;
> -}
> -
>  static const struct drm_mode_config_funcs mode_config_funcs = {
>  	.fb_create = drm_gem_fb_create,
>  	.atomic_check = drm_atomic_helper_check,
> -	.atomic_commit = atmel_hlcdc_dc_atomic_commit,
> +	.atomic_commit = drm_atomic_helper_commit,
>  };
>  
>  static int atmel_hlcdc_dc_modeset_init(struct drm_device *dev)
> @@ -712,11 +619,6 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
>  	if (!dc)
>  		return -ENOMEM;
>  
> -	dc->wq = alloc_ordered_workqueue("atmel-hlcdc-dc", 0);
> -	if (!dc->wq)
> -		return -ENOMEM;
> -
> -	init_waitqueue_head(&dc->commit.wait);
>  	dc->desc = match->data;
>  	dc->hlcdc = dev_get_drvdata(dev->dev->parent);
>  	dev->dev_private = dc;
> @@ -724,7 +626,7 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
>  	ret = clk_prepare_enable(dc->hlcdc->periph_clk);
>  	if (ret) {
>  		dev_err(dev->dev, "failed to enable periph_clk\n");
> -		goto err_destroy_wq;
> +		return ret;
>  	}
>  
>  	pm_runtime_enable(dev->dev);
> @@ -761,9 +663,6 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
>  	pm_runtime_disable(dev->dev);
>  	clk_disable_unprepare(dc->hlcdc->periph_clk);
>  
> -err_destroy_wq:
> -	destroy_workqueue(dc->wq);
> -
>  	return ret;
>  }
>  
> @@ -771,7 +670,6 @@ static void atmel_hlcdc_dc_unload(struct drm_device *dev)
>  {
>  	struct atmel_hlcdc_dc *dc = dev->dev_private;
>  
> -	flush_workqueue(dc->wq);
>  	drm_kms_helper_poll_fini(dev);
>  	drm_atomic_helper_shutdown(dev);
>  	drm_mode_config_cleanup(dev);
> @@ -784,7 +682,6 @@ static void atmel_hlcdc_dc_unload(struct drm_device *dev)
>  
>  	pm_runtime_disable(dev->dev);
>  	clk_disable_unprepare(dc->hlcdc->periph_clk);
> -	destroy_workqueue(dc->wq);
>  }
>  
>  static int atmel_hlcdc_dc_irq_postinstall(struct drm_device *dev)
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> index 469d4507e576..5b5c774e0edf 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> @@ -331,9 +331,7 @@ struct atmel_hlcdc_dc_desc {
>   * @crtc: CRTC provided by the display controller
>   * @planes: instantiated planes
>   * @layers: active HLCDC layers
> - * @wq: display controller workqueue
>   * @suspend: used to store the HLCDC state when entering suspend
> - * @commit: used for async commit handling
>   */
>  struct atmel_hlcdc_dc {
>  	const struct atmel_hlcdc_dc_desc *desc;
> @@ -341,15 +339,10 @@ struct atmel_hlcdc_dc {
>  	struct atmel_hlcdc *hlcdc;
>  	struct drm_crtc *crtc;
>  	struct atmel_hlcdc_layer *layers[ATMEL_HLCDC_MAX_LAYERS];
> -	struct workqueue_struct *wq;
>  	struct {
>  		u32 imr;
>  		struct drm_atomic_state *state;
>  	} suspend;
> -	struct {
> -		wait_queue_head_t wait;
> -		bool pending;
> -	} commit;
>  };
>  
>  extern struct atmel_hlcdc_formats atmel_hlcdc_plane_rgb_formats;
> -- 
> 2.27.0
> 
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