[PATCH v2 3/4] media: staging: rkisp1: stats: replace locks wq_lock, irq_lock with one lock

[Helen Koike]

Hi Dafna,

On 6/26/20 5:51 AM, Dafna Hirschfeld wrote:
> This patch removes two locks in the rkisp1_stats struct:
> - The mutex 'wq_lock' that is used to protect the buffers list 'stat'
> - The spin_lock 'irq_lock' that is used to protect the
> variable 'is_streaming'
> 
> It replaces them with one spin_lock 'lock' that protects
> both the buffers list and the 'is_streaming' variable.
> In later patch the reading of the statistics will move to
> the isr so there will be no need for the mutex 'wq_lock'
> 
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld at collabora.com>

Acked-by: Helen Koike <helen.koike at collabora.com>

Thanks
Helen

> ---
>  drivers/staging/media/rkisp1/rkisp1-common.h |  5 ++--
>  drivers/staging/media/rkisp1/rkisp1-stats.c  | 25 +++++++++-----------
>  2 files changed, 13 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/staging/media/rkisp1/rkisp1-common.h b/drivers/staging/media/rkisp1/rkisp1-common.h
> index d2c669091fae..c92ae1b7093f 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-common.h
> +++ b/drivers/staging/media/rkisp1/rkisp1-common.h
> @@ -178,7 +178,7 @@ struct rkisp1_capture {
>  /*
>   * struct rkisp1_stats - ISP Statistics device
>   *
> - * @irq_lock: buffer queue lock
> + * @lock: locks the buffer list 'stat' and 'is_streaming'
>   * @stat: stats buffer list
>   * @readout_wq: workqueue for statistics information read
>   */
> @@ -186,13 +186,12 @@ struct rkisp1_stats {
>  	struct rkisp1_vdev_node vnode;
>  	struct rkisp1_device *rkisp1;
>  
> -	spinlock_t irq_lock;
> +	spinlock_t lock; /* locks 'is_streaming', and 'stats' */
>  	struct list_head stat;
>  	struct v4l2_format vdev_fmt;
>  	bool is_streaming;
>  
>  	struct workqueue_struct *readout_wq;
> -	struct mutex wq_lock;
>  };
>  
>  /*
> diff --git a/drivers/staging/media/rkisp1/rkisp1-stats.c b/drivers/staging/media/rkisp1/rkisp1-stats.c
> index d4f0df4342e0..58329e6b0598 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-stats.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-stats.c
> @@ -133,9 +133,9 @@ static void rkisp1_stats_vb2_buf_queue(struct vb2_buffer *vb)
>  
>  	stats_buf->vaddr[0] = vb2_plane_vaddr(vb, 0);
>  
> -	mutex_lock(&stats_dev->wq_lock);
> +	spin_lock_irq(&stats_dev->lock);
>  	list_add_tail(&stats_buf->queue, &stats_dev->stat);
> -	mutex_unlock(&stats_dev->wq_lock);
> +	spin_unlock_irq(&stats_dev->lock);
>  }
>  
>  static int rkisp1_stats_vb2_buf_prepare(struct vb2_buffer *vb)
> @@ -155,13 +155,13 @@ static void rkisp1_stats_vb2_stop_streaming(struct vb2_queue *vq)
>  	unsigned int i;
>  
>  	/* Make sure no new work queued in isr before draining wq */
> -	spin_lock_irq(&stats->irq_lock);
> +	spin_lock_irq(&stats->lock);
>  	stats->is_streaming = false;
> -	spin_unlock_irq(&stats->irq_lock);
> +	spin_unlock_irq(&stats->lock);
>  
>  	drain_workqueue(stats->readout_wq);
>  
> -	mutex_lock(&stats->wq_lock);
> +	spin_lock_irq(&stats->lock);
>  	for (i = 0; i < RKISP1_ISP_STATS_REQ_BUFS_MAX; i++) {
>  		if (list_empty(&stats->stat))
>  			break;
> @@ -170,7 +170,7 @@ static void rkisp1_stats_vb2_stop_streaming(struct vb2_queue *vq)
>  		list_del(&buf->queue);
>  		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
>  	}
> -	mutex_unlock(&stats->wq_lock);
> +	spin_unlock_irq(&stats->lock);
>  }
>  
>  static int
> @@ -340,14 +340,14 @@ rkisp1_stats_send_measurement(struct rkisp1_stats *stats,
>  		frame_sequence = meas_work->frame_id;
>  	}
>  
> -	mutex_lock(&stats->wq_lock);
> +	spin_lock_irq(&stats->lock);
>  	/* get one empty buffer */
>  	if (!list_empty(&stats->stat)) {
>  		cur_buf = list_first_entry(&stats->stat,
>  					   struct rkisp1_buffer, queue);
>  		list_del(&cur_buf->queue);
>  	}
> -	mutex_unlock(&stats->wq_lock);
> +	spin_unlock_irq(&stats->lock);
>  
>  	if (!cur_buf)
>  		return;
> @@ -396,7 +396,7 @@ void rkisp1_stats_isr(struct rkisp1_stats *stats, u32 isp_ris)
>  	struct rkisp1_isp_readout_work *work;
>  	unsigned int isp_mis_tmp = 0;
>  
> -	spin_lock(&stats->irq_lock);
> +	spin_lock(&stats->lock);
>  
>  	rkisp1_write(rkisp1, RKISP1_STATS_MEAS_MASK, RKISP1_CIF_ISP_ICR);
>  
> @@ -425,7 +425,7 @@ void rkisp1_stats_isr(struct rkisp1_stats *stats, u32 isp_ris)
>  	}
>  
>  unlock:
> -	spin_unlock(&stats->irq_lock);
> +	spin_unlock(&stats->lock);
>  }
>  
>  static void rkisp1_init_stats(struct rkisp1_stats *stats)
> @@ -445,10 +445,9 @@ int rkisp1_stats_register(struct rkisp1_stats *stats,
>  	int ret;
>  
>  	stats->rkisp1 = rkisp1;
> -	mutex_init(&stats->wq_lock);
>  	mutex_init(&node->vlock);
>  	INIT_LIST_HEAD(&stats->stat);
> -	spin_lock_init(&stats->irq_lock);
> +	spin_lock_init(&stats->lock);
>  
>  	strscpy(vdev->name, RKISP1_STATS_DEV_NAME, sizeof(vdev->name));
>  
> @@ -495,7 +494,6 @@ int rkisp1_stats_register(struct rkisp1_stats *stats,
>  err_release_queue:
>  	vb2_queue_release(vdev->queue);
>  	mutex_destroy(&node->vlock);
> -	mutex_destroy(&stats->wq_lock);
>  	return ret;
>  }
>  
> @@ -509,5 +507,4 @@ void rkisp1_stats_unregister(struct rkisp1_stats *stats)
>  	media_entity_cleanup(&vdev->entity);
>  	vb2_queue_release(vdev->queue);
>  	mutex_destroy(&node->vlock);
> -	mutex_destroy(&stats->wq_lock);
>  }
>