Re: [PATCH v4 09/11] media: vsp1: Provide support for extended command pools

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

Hi Kieran,

Thank you for the patch.

On Thursday, 3 May 2018 16:36:20 EEST Kieran Bingham wrote:
> VSPD and VSP-DL devices can provide extended display lists supporting
> extended command display list objects.
> 
> These extended commands require their own dma memory areas for a header
> and body specific to the command type.
> 
> Implement a command pool to allocate all necessary memory in a single
> DMA allocation to reduce pressure on the TLB, and provide convenient
> re-usable command objects for the entities to utilise.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> 
> ---
> 
> v2:
>  - Fix spelling typo in commit message
>  - constify, and staticify the instantiation of vsp1_extended_commands
>  - s/autfld_cmds/autofld_cmds/
>  - staticify cmd pool functions (Thanks kbuild-bot)
> ---
>  drivers/media/platform/vsp1/vsp1_dl.c | 191 +++++++++++++++++++++++++++-
>  drivers/media/platform/vsp1/vsp1_dl.h |   3 +-
>  2 files changed, 194 insertions(+)
> 
> diff --git a/drivers/media/platform/vsp1/vsp1_dl.c
> b/drivers/media/platform/vsp1/vsp1_dl.c index b64d32535edc..d33ae5f125bd
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_dl.c
> +++ b/drivers/media/platform/vsp1/vsp1_dl.c
> @@ -117,6 +117,30 @@ struct vsp1_dl_body_pool {
>  };
> 
>  /**
> + * struct vsp1_cmd_pool - display list body pool

The structure is called vsp1_dl_cmd_pool. I would document it as "Display list 
commands pool", not "body pool".

> + * @dma: DMA address of the entries
> + * @size: size of the full DMA memory pool in bytes
> + * @mem: CPU memory pointer for the pool
> + * @bodies: Array of DLB structures for the pool

The field is called cmds.

> + * @free: List of free DLB entries

"free pool entries" or "free command entries" ?

> + * @lock: Protects the pool and free list

The pool is the whole structure, does the lock really protects all fields ?

> + * @vsp1: the VSP1 device
> + */
> +struct vsp1_dl_cmd_pool {
> +	/* DMA allocation */
> +	dma_addr_t dma;
> +	size_t size;
> +	void *mem;
> +
> +	struct vsp1_dl_ext_cmd *cmds;
> +	struct list_head free;
> +
> +	spinlock_t lock;
> +
> +	struct vsp1_device *vsp1;
> +};
> +
> +/**
>   * struct vsp1_dl_list - Display list
>   * @list: entry in the display list manager lists
>   * @dlm: the display list manager
> @@ -162,6 +186,7 @@ struct vsp1_dl_list {
>   * @queued: list queued to the hardware (written to the DL registers)
>   * @pending: list waiting to be queued to the hardware
>   * @pool: body pool for the display list bodies
> + * @autofld_cmds: command pool to support auto-fld interlaced mode

This could also be used for auto-disp. How about calling it cmdpool ?

>   */
>  struct vsp1_dl_manager {
>  	unsigned int index;
> @@ -175,6 +200,7 @@ struct vsp1_dl_manager {
>  	struct vsp1_dl_list *pending;
> 
>  	struct vsp1_dl_body_pool *pool;
> +	struct vsp1_dl_cmd_pool *autofld_cmds;
>  };
> 
>  /* ------------------------------------------------------------------------
> @@ -338,6 +364,140 @@ void vsp1_dl_body_write(struct vsp1_dl_body *dlb,
> u32 reg, u32 data) }
> 
>  /* ------------------------------------------------------------------------
> + * Display List Extended Command Management
> + */
> +
> +enum vsp1_extcmd_type {
> +	VSP1_EXTCMD_AUTODISP,
> +	VSP1_EXTCMD_AUTOFLD,
> +};
> +
> +struct vsp1_extended_command_info {
> +	u16 opcode;
> +	size_t body_size;
> +} static const vsp1_extended_commands[] = {

The location of the static const keywords is strange. I would move them before 
struct, or split the structure definition and variable declaration.

> +	[VSP1_EXTCMD_AUTODISP] = { 0x02, 96 },
> +	[VSP1_EXTCMD_AUTOFLD]  = { 0x03, 160 },
> +};
> +
> +/**
> + * vsp1_dl_cmd_pool_create - Create a pool of commands from a single
> allocation
> + * @vsp1: The VSP1 device
> + * @type: The command pool type
> + * @num_commands: The quantity of commands to allocate

s/quantity/number/ ?

> + *
> + * Allocate a pool of commands each with enough memory to contain the
> private
> + * data of each command. The allocation sizes are dependent upon the
> command
> + * type.
> + *
> + * Return a pointer to a pool on success or NULL if memory can't be

s/a pool/the pool/

> allocated.
> + */
> +static struct vsp1_dl_cmd_pool *
> +vsp1_dl_cmd_pool_create(struct vsp1_device *vsp1, enum vsp1_extcmd_type
> type,
> +			unsigned int num_cmds)
> +{
> +	struct vsp1_dl_cmd_pool *pool;
> +	unsigned int i;
> +	size_t cmd_size;
> +
> +	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
> +	if (!pool)
> +		return NULL;
> +
> +	pool->cmds = kcalloc(num_cmds, sizeof(*pool->cmds), GFP_KERNEL);
> +	if (!pool->cmds) {
> +		kfree(pool);
> +		return NULL;
> +	}
> +
> +	cmd_size = sizeof(struct vsp1_dl_ext_cmd_header) +
> +		   vsp1_extended_commands[type].body_size;
> +	cmd_size = ALIGN(cmd_size, 16);
> +
> +	pool->size = cmd_size * num_cmds;
> +	pool->mem = dma_alloc_wc(vsp1->bus_master, pool->size, &pool->dma,
> +				 GFP_KERNEL);
> +	if (!pool->mem) {
> +		kfree(pool->cmds);
> +		kfree(pool);
> +		return NULL;
> +	}
> +
> +	spin_lock_init(&pool->lock);
> +	INIT_LIST_HEAD(&pool->free);

I would move these two lines right after allocation of pool, I find it more 
readable to perform small and simple initialization right away.

> +	for (i = 0; i < num_cmds; ++i) {
> +		struct vsp1_dl_ext_cmd *cmd = &pool->cmds[i];
> +		size_t cmd_offset = i * cmd_size;
> +		size_t data_offset = sizeof(struct vsp1_dl_ext_cmd_header) +
> +				     cmd_offset;

The data memory has to be 16-bytes aligned. This is guaranteed as the header 
is 16 bytes long, and cmd_size is aligned to 16 bytes, but it would be worth 
adding a comment to explain this.

> +		cmd->pool = pool;
> +		cmd->cmd_opcode = vsp1_extended_commands[type].opcode;
> +
> +		/* TODO: Auto-disp can utilise more than one command per cmd */

That will be annoying to handle :-/

> +		cmd->num_cmds = 1;
> +		cmd->cmds = pool->mem + cmd_offset;
> +		cmd->cmd_dma = pool->dma + cmd_offset;
> +
> +		cmd->data = pool->mem + data_offset;
> +		cmd->data_dma = pool->dma + data_offset;
> +		cmd->data_size = vsp1_extended_commands[type].body_size;
> +
> +		list_add_tail(&cmd->free, &pool->free);
> +	}
> +
> +	return pool;
> +}
> +
> +static
> +struct vsp1_dl_ext_cmd *vsp1_dl_ext_cmd_get(struct vsp1_dl_cmd_pool *pool)
> +{
> +	struct vsp1_dl_ext_cmd *cmd = NULL;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pool->lock, flags);
> +
> +	if (!list_empty(&pool->free)) {
> +		cmd = list_first_entry(&pool->free, struct vsp1_dl_ext_cmd,
> +				       free);
> +		list_del(&cmd->free);
> +	}
> +
> +	spin_unlock_irqrestore(&pool->lock, flags);
> +
> +	return cmd;
> +}
> +
> +static void vsp1_dl_ext_cmd_put(struct vsp1_dl_ext_cmd *cmd)
> +{
> +	unsigned long flags;
> +
> +	if (!cmd)
> +		return;
> +
> +	/* Reset flags, these mark data usage */

s/usage/usage./

> +	cmd->flags = 0;
> +
> +	spin_lock_irqsave(&cmd->pool->lock, flags);
> +	list_add_tail(&cmd->free, &cmd->pool->free);
> +	spin_unlock_irqrestore(&cmd->pool->lock, flags);
> +}
> +
> +static void vsp1_dl_ext_cmd_pool_destroy(struct vsp1_dl_cmd_pool *pool)
> +{
> +	if (!pool)
> +		return;
> +
> +	if (pool->mem)
> +		dma_free_wc(pool->vsp1->bus_master, pool->size, pool->mem,
> +			    pool->dma);
> +
> +	kfree(pool->cmds);
> +	kfree(pool);
> +}
> +
> +/* ------------------------------------------------------------------------
> - * Display List Transaction Management
>   */
> 
> @@ -440,6 +600,12 @@ static void __vsp1_dl_list_put(struct vsp1_dl_list *dl)
> 
>  	vsp1_dl_list_bodies_put(dl);
> 
> +	vsp1_dl_ext_cmd_put(dl->pre_cmd);
> +	vsp1_dl_ext_cmd_put(dl->post_cmd);
> +
> +	dl->pre_cmd = NULL;
> +	dl->post_cmd = NULL;
> +
>  	/*
>  	 * body0 is reused as as an optimisation as presently every display list
>  	 * has at least one body, thus we reinitialise the entries list.
> @@ -883,6 +1049,15 @@ struct vsp1_dl_manager *vsp1_dlm_create(struct
> vsp1_device *vsp1, list_add_tail(&dl->list, &dlm->free);
>  	}
> 
> +	if (vsp1_feature(vsp1, VSP1_HAS_EXT_DL)) {
> +		dlm->autofld_cmds = vsp1_dl_cmd_pool_create(vsp1,
> +					VSP1_EXTCMD_AUTOFLD, prealloc);
> +		if (!dlm->autofld_cmds) {
> +			vsp1_dlm_destroy(dlm);
> +			return NULL;
> +		}
> +	}
> +
>  	return dlm;
>  }
> 
> @@ -899,4 +1074,20 @@ void vsp1_dlm_destroy(struct vsp1_dl_manager *dlm)
>  	}
> 
>  	vsp1_dl_body_pool_destroy(dlm->pool);
> +	vsp1_dl_ext_cmd_pool_destroy(dlm->autofld_cmds);
> +}
> +
> +struct vsp1_dl_ext_cmd *vsp1_dlm_get_autofld_cmd(struct vsp1_dl_list *dl)
> +{
> +	struct vsp1_dl_manager *dlm = dl->dlm;
> +	struct vsp1_dl_ext_cmd *cmd;
> +
> +	if (dl->pre_cmd)
> +		return dl->pre_cmd;
> +
> +	cmd = vsp1_dl_ext_cmd_get(dlm->autofld_cmds);
> +	if (cmd)
> +		dl->pre_cmd = cmd;
> +
> +	return cmd;

You can write it in a simpler way.

	dl->pre_cmd = vsp1_dl_ext_cmd_get(dlm->autofld_cmds);
	return dl->pre_cmd;

>  }
> diff --git a/drivers/media/platform/vsp1/vsp1_dl.h
> b/drivers/media/platform/vsp1/vsp1_dl.h index aa5f4adc6617..d9621207b093
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_dl.h
> +++ b/drivers/media/platform/vsp1/vsp1_dl.h
> @@ -22,6 +22,7 @@ struct vsp1_dl_manager;
> 
>  /**
>   * struct vsp1_dl_ext_cmd - Extended Display command
> + * @pool: pool to which this command belongs
>   * @free: entry in the pool of free commands list
>   * @cmd_opcode: command type opcode
>   * @flags: flags used by the command
> @@ -33,6 +34,7 @@ struct vsp1_dl_manager;
>   * @data_size: size of the @data_dma memory in bytes
>   */
>  struct vsp1_dl_ext_cmd {
> +	struct vsp1_dl_cmd_pool *pool;
>  	struct list_head free;
> 
>  	u8 cmd_opcode;
> @@ -55,6 +57,7 @@ struct vsp1_dl_manager *vsp1_dlm_create(struct vsp1_device
> *vsp1, void vsp1_dlm_destroy(struct vsp1_dl_manager *dlm);
>  void vsp1_dlm_reset(struct vsp1_dl_manager *dlm);
>  unsigned int vsp1_dlm_irq_frame_end(struct vsp1_dl_manager *dlm);
> +struct vsp1_dl_ext_cmd *vsp1_dlm_get_autofld_cmd(struct vsp1_dl_list *dl);

Should this be named vsp1_dl_get_autofld_cmd() as it operates on a dl ? I also 
think that you should move it down to group it with the dl functions.

>  struct vsp1_dl_list *vsp1_dl_list_get(struct vsp1_dl_manager *dlm);
>  void vsp1_dl_list_put(struct vsp1_dl_list *dl);

-- 
Regards,

Laurent Pinchart