linux-kernel - Re: [PATCH v2 10/22] media: rockchip: rga: prepare cmdbuf on streamon

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Message-ID: <8c3a3299036dd1bab158bdcd589abd027d2864b6.camel@ndufresne.ca>
Date: Wed, 24 Dec 2025 10:29:41 -0500
From: Nicolas Dufresne <nicolas@...fresne.ca>
To: Sven Püschel <s.pueschel@...gutronix.de>, Jacob Chen
	 <jacob-chen@...wrt.com>, Ezequiel Garcia <ezequiel@...guardiasur.com.ar>, 
 Mauro Carvalho Chehab
	 <mchehab@...nel.org>, Heiko Stuebner <heiko@...ech.de>, Rob Herring
	 <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
	 <conor+dt@...nel.org>
Cc: linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, kernel@...gutronix.de
Subject: Re: [PATCH v2 10/22] media: rockchip: rga: prepare cmdbuf on
 streamon

Hi,

Le mercredi 03 décembre 2025 à 16:52 +0100, Sven Püschel a écrit :
> Prepare the command buffer on streamon to reuse it's contents instead of
> completely writing it for every frame. Due to the stream settings being
> fixed after a streamon we only need to replace the source and destination
> addresses for each frame. This reduces the amount of CPU and memory
> operations done in each frame.

My speculation is that flushing to device is usually more expensive then this,
but I didn't check closely if you have enabled the caches. That being said, this
is good change. It highlight the inflexible nature of V4L2 imho, which in this
case can be used to optimize.

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>

> 
> Signed-off-by: Sven Püschel <s.pueschel@...gutronix.de>
> ---
>  drivers/media/platform/rockchip/rga/rga-hw.c | 13 +++++++++----
>  drivers/media/platform/rockchip/rga/rga.c    | 13 ++++++++++++-
>  drivers/media/platform/rockchip/rga/rga.h    |  1 +
>  3 files changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/platform/rockchip/rga/rga-hw.c b/drivers/media/platform/rockchip/rga/rga-hw.c
> index 56a2558539bfb..8cdfe089fd636 100644
> --- a/drivers/media/platform/rockchip/rga/rga-hw.c
> +++ b/drivers/media/platform/rockchip/rga/rga-hw.c
> @@ -408,8 +408,6 @@ static void rga_cmd_set(struct rga_ctx *ctx,
>  {
>  	struct rockchip_rga *rga = ctx->rga;
>  
> -	memset(ctx->cmdbuf_virt, 0, RGA_CMDBUF_SIZE * 4);
> -
>  	rga_cmd_set_src_addr(ctx, src->dma_desc_pa);
>  	/*
>  	 * Due to hardware bug,
> @@ -418,11 +416,9 @@ static void rga_cmd_set(struct rga_ctx *ctx,
>  	rga_cmd_set_src1_addr(ctx, dst->dma_desc_pa);
>  
>  	rga_cmd_set_dst_addr(ctx, dst->dma_desc_pa);
> -	rga_cmd_set_mode(ctx);
>  
>  	rga_cmd_set_src_info(ctx, &src->offset);
>  	rga_cmd_set_dst_info(ctx, &dst->offset);
> -	rga_cmd_set_trans_info(ctx);
>  
>  	rga_write(rga, RGA_CMD_BASE, ctx->cmdbuf_phy);
>  
> @@ -431,6 +427,14 @@ static void rga_cmd_set(struct rga_ctx *ctx,
>  				   PAGE_SIZE, DMA_BIDIRECTIONAL);
>  }
>  
> +static void rga_hw_setup_cmdbuf(struct rga_ctx *ctx)
> +{
> +	memset(ctx->cmdbuf_virt, 0, RGA_CMDBUF_SIZE * 4);
> +
> +	rga_cmd_set_mode(ctx);
> +	rga_cmd_set_trans_info(ctx);
> +}
> +
>  static void rga_hw_start(struct rockchip_rga *rga,
>  			 struct rga_vb_buffer *src,  struct rga_vb_buffer *dst)
>  {
> @@ -622,6 +626,7 @@ const struct rga_hw rga2_hw = {
>  	.max_height = MAX_HEIGHT,
>  	.stride_alignment = 4,
>  
> +	.setup_cmdbuf = rga_hw_setup_cmdbuf,
>  	.start = rga_hw_start,
>  	.handle_irq = rga_handle_irq,
>  	.get_version = rga_get_version,
> diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> index 592c977a07cf3..f02ae02de26ca 100644
> --- a/drivers/media/platform/rockchip/rga/rga.c
> +++ b/drivers/media/platform/rockchip/rga/rga.c
> @@ -523,6 +523,17 @@ static int vidioc_s_selection(struct file *file, void *priv,
>  	return ret;
>  }
>  
> +static int vidioc_streamon(struct file *file, void *priv,
> +			   enum v4l2_buf_type type)
> +{
> +	struct rga_ctx *ctx = file_to_rga_ctx(file);
> +	const struct rga_hw *hw = ctx->rga->hw;
> +
> +	hw->setup_cmdbuf(ctx);
> +
> +	return v4l2_m2m_streamon(file, ctx->fh.m2m_ctx, type);
> +}
> +
>  static const struct v4l2_ioctl_ops rga_ioctl_ops = {
>  	.vidioc_querycap = vidioc_querycap,
>  
> @@ -547,7 +558,7 @@ static const struct v4l2_ioctl_ops rga_ioctl_ops = {
>  	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
>  	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
>  
> -	.vidioc_streamon = v4l2_m2m_ioctl_streamon,
> +	.vidioc_streamon = vidioc_streamon,
>  	.vidioc_streamoff = v4l2_m2m_ioctl_streamoff,
>  
>  	.vidioc_g_selection = vidioc_g_selection,
> diff --git a/drivers/media/platform/rockchip/rga/rga.h b/drivers/media/platform/rockchip/rga/rga.h
> index 0aef348dddb95..93162b118d069 100644
> --- a/drivers/media/platform/rockchip/rga/rga.h
> +++ b/drivers/media/platform/rockchip/rga/rga.h
> @@ -154,6 +154,7 @@ struct rga_hw {
>  	u32 max_width, max_height;
>  	u8 stride_alignment;
>  
> +	void (*setup_cmdbuf)(struct rga_ctx *ctx);
>  	void (*start)(struct rockchip_rga *rga,
>  		      struct rga_vb_buffer *src, struct rga_vb_buffer *dst);
>  	bool (*handle_irq)(struct rockchip_rga *rga);

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