Re: [PATCH v4 21/27] rcar-vin: add group allocator functions

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Hi Niklas,

On Fri, Apr 28, 2017 at 12:41:57AM +0200, Niklas Söderlund wrote:
> In media controller mode all VIN instances needs to be part of the same
> media graph. There is also a need to each VIN instance to know and in
> some cases be able to communicate with other VIN instances.
> 
> Add a allocator framework where the first VIN instance to be probed
> creates a shared data structure and creates a media device.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
>  drivers/media/platform/rcar-vin/rcar-core.c | 112 +++++++++++++++++++++++++++-
>  drivers/media/platform/rcar-vin/rcar-vin.h  |  38 ++++++++++
>  2 files changed, 147 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
> index f560d27449b84882..c10770d5ec37816c 100644
> --- a/drivers/media/platform/rcar-vin/rcar-core.c
> +++ b/drivers/media/platform/rcar-vin/rcar-core.c
> @@ -20,12 +20,110 @@
>  #include <linux/of_graph.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/slab.h>
>  
>  #include <media/v4l2-of.h>
>  
>  #include "rcar-vin.h"
>  
>  /* -----------------------------------------------------------------------------
> + * Gen3 CSI2 Group Allocator
> + */
> +
> +static DEFINE_MUTEX(rvin_group_lock);
> +static struct rvin_group *rvin_group_data;

Uh-oh.

It'd be nice to find a way for managing the group of devices without a
global list for the group.

Do all the callers operating on a group have some kind of identifying
information, e.g. OF node or struct device? Could it be used to obtain the
group?

I'm not sure if this would be a real problem though as long as you have only
a single group in a system.

> +
> +static void rvin_group_release(struct kref *kref)
> +{
> +	struct rvin_group *group =
> +		container_of(kref, struct rvin_group, refcount);
> +
> +	mutex_lock(&rvin_group_lock);
> +
> +	media_device_unregister(&group->mdev);
> +	media_device_cleanup(&group->mdev);
> +
> +	rvin_group_data = NULL;
> +
> +	mutex_unlock(&rvin_group_lock);
> +
> +	kfree(group);
> +}
> +
> +static struct rvin_group *__rvin_group_allocate(struct rvin_dev *vin)
> +{
> +	struct rvin_group *group;
> +
> +	if (rvin_group_data) {
> +		group = rvin_group_data;
> +		kref_get(&group->refcount);
> +		vin_dbg(vin, "%s: get group=%p\n", __func__, group);
> +		return group;
> +	}
> +
> +	group = kzalloc(sizeof(*group), GFP_KERNEL);
> +	if (!group)
> +		return NULL;
> +
> +	kref_init(&group->refcount);
> +	rvin_group_data = group;
> +
> +	vin_dbg(vin, "%s: alloc group=%p\n", __func__, group);
> +	return group;
> +}
> +
> +static struct rvin_group *rvin_group_allocate(struct rvin_dev *vin)
> +{
> +	struct rvin_group *group;
> +	struct media_device *mdev;
> +	int ret;
> +
> +	mutex_lock(&rvin_group_lock);
> +
> +	group = __rvin_group_allocate(vin);
> +	if (!group) {
> +		mutex_unlock(&rvin_group_lock);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	/* Init group data if its not already initialized */
> +	mdev = &group->mdev;
> +	if (!mdev->dev) {
> +		mutex_init(&group->lock);
> +		mdev->dev = vin->dev;
> +
> +		strlcpy(mdev->driver_name, "Renesas VIN",
> +			sizeof(mdev->driver_name));
> +		strlcpy(mdev->model, vin->dev->of_node->name,
> +			sizeof(mdev->model));
> +		strlcpy(mdev->bus_info, of_node_full_name(vin->dev->of_node),
> +			sizeof(mdev->bus_info));
> +		mdev->driver_version = LINUX_VERSION_CODE;
> +		media_device_init(mdev);
> +
> +		ret = media_device_register(mdev);
> +		if (ret) {
> +			vin_err(vin, "Failed to register media device\n");
> +			kref_put(&group->refcount, rvin_group_release);
> +			mutex_unlock(&rvin_group_lock);
> +			return ERR_PTR(ret);
> +		}
> +	}
> +
> +	vin->v4l2_dev.mdev = mdev;
> +
> +	mutex_unlock(&rvin_group_lock);
> +
> +	return group;
> +}
> +
> +static void rvin_group_delete(struct rvin_dev *vin)
> +{
> +	vin_dbg(vin, "%s: group=%p\n", __func__, &vin->group);
> +	kref_put(&vin->group->refcount, rvin_group_release);
> +}
> +
> +/* -----------------------------------------------------------------------------
>   * Async notifier
>   */
>  
> @@ -263,9 +361,13 @@ static int rvin_group_init(struct rvin_dev *vin)
>  {
>  	int ret;
>  
> +	vin->group = rvin_group_allocate(vin);
> +	if (IS_ERR(vin->group))
> +		return PTR_ERR(vin->group);
> +
>  	ret = rvin_v4l2_mc_probe(vin);
>  	if (ret)
> -		return ret;
> +		goto error_group;
>  
>  	vin->pad.flags = MEDIA_PAD_FL_SINK;
>  	ret = media_entity_pads_init(&vin->vdev->entity, 1, &vin->pad);
> @@ -275,6 +377,8 @@ static int rvin_group_init(struct rvin_dev *vin)
>  	return 0;
>  error_v4l2:
>  	rvin_v4l2_mc_remove(vin);
> +error_group:
> +	rvin_group_delete(vin);
>  
>  	return ret;
>  }
> @@ -398,10 +502,12 @@ static int rcar_vin_remove(struct platform_device *pdev)
>  
>  	v4l2_async_notifier_unregister(&vin->notifier);
>  
> -	if (vin->info->use_mc)
> +	if (vin->info->use_mc) {
>  		rvin_v4l2_mc_remove(vin);
> -	else
> +		rvin_group_delete(vin);
> +	} else {
>  		rvin_v4l2_remove(vin);
> +	}
>  
>  	rvin_dma_remove(vin);
>  
> diff --git a/drivers/media/platform/rcar-vin/rcar-vin.h b/drivers/media/platform/rcar-vin/rcar-vin.h
> index 06934313950253f4..21b6c9292686e41a 100644
> --- a/drivers/media/platform/rcar-vin/rcar-vin.h
> +++ b/drivers/media/platform/rcar-vin/rcar-vin.h
> @@ -17,6 +17,8 @@
>  #ifndef __RCAR_VIN__
>  #define __RCAR_VIN__
>  
> +#include <linux/kref.h>
> +
>  #include <media/v4l2-async.h>
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-dev.h>
> @@ -30,6 +32,9 @@
>  /* Address alignment mask for HW buffers */
>  #define HW_BUFFER_MASK 0x7f
>  
> +/* Max number on VIN instances that can be in a system */
> +#define RCAR_VIN_NUM 8
> +
>  enum chip_id {
>  	RCAR_H1,
>  	RCAR_M1,
> @@ -37,6 +42,15 @@ enum chip_id {
>  	RCAR_GEN3,
>  };
>  
> +enum rvin_csi_id {
> +	RVIN_CSI20,
> +	RVIN_CSI21,
> +	RVIN_CSI40,
> +	RVIN_CSI41,
> +	RVIN_CSI_MAX,
> +	RVIN_NC, /* Not Connected */
> +};
> +
>  /**
>   * STOPPED  - No operation in progress
>   * RUNNING  - Operation in progress have buffers
> @@ -75,6 +89,8 @@ struct rvin_graph_entity {
>  	unsigned int sink_pad;
>  };
>  
> +struct rvin_group;
> +
>  /**
>   * struct rvin_info- Information about the particular VIN implementation
>   * @chip:		type of VIN chip
> @@ -103,6 +119,7 @@ struct rvin_info {
>   * @notifier:		V4L2 asynchronous subdevs notifier
>   * @digital:		entity in the DT for local digital subdevice
>   *
> + * @group:		Gen3 CSI group
>   * @pad:		pad for media controller
>   *
>   * @lock:		protects @queue
> @@ -134,6 +151,7 @@ struct rvin_dev {
>  	struct v4l2_async_notifier notifier;
>  	struct rvin_graph_entity digital;
>  
> +	struct rvin_group *group;
>  	struct media_pad pad;
>  
>  	struct mutex lock;
> @@ -162,6 +180,26 @@ struct rvin_dev {
>  #define vin_warn(d, fmt, arg...)	dev_warn(d->dev, fmt, ##arg)
>  #define vin_err(d, fmt, arg...)		dev_err(d->dev, fmt, ##arg)
>  
> +/**
> + * struct rvin_group - VIN CSI2 group information
> + * @refcount:		number of VIN instances using the group
> + *
> + * @mdev:		media device which represents the group
> + *
> + * @lock:		protects the vin and csi members
> + * @vin:		VIN instances which are part of the group
> + * @csi:		CSI-2 entities that are part of the group
> + */
> +struct rvin_group {
> +	struct kref refcount;
> +
> +	struct media_device mdev;
> +
> +	struct mutex lock;
> +	struct rvin_dev *vin[RCAR_VIN_NUM];
> +	struct rvin_graph_entity csi[RVIN_CSI_MAX];
> +};
> +
>  int rvin_dma_probe(struct rvin_dev *vin, int irq);
>  void rvin_dma_remove(struct rvin_dev *vin);
>  

-- 
Regards,

Sakari Ailus
e-mail: sakari.ailus@xxxxxx	XMPP: sailus@xxxxxxxxxxxxxx



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