linux-kernel - Re: [PATCH 1/3] dmaengine: Add support for 2D DMA operation

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Message-ID: <Z8Ab3VcAXf5z7UqE@vaman>
Date: Thu, 27 Feb 2025 13:31:33 +0530
From: Vinod Koul <vkoul@...nel.org>
To: Aatif Mushtaq <aatif4.m@...sung.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	pankaj.dubey@...sung.com, aswani.reddy@...sung.com
Subject: Re: [PATCH 1/3] dmaengine: Add support for 2D DMA operation

On 10-02-25, 11:49, Aatif Mushtaq wrote:
> Add a new dma engine API to support 2D DMA operations.
> The API will be used to get the descriptor for 2D transfer based on
> the 16-bit immediate to define the stride length between consecuitive
> source address or destination address after every DMA load and
> store instruction is processed.

Why should we define a new API for this...? Why not use the sg or
interleaved api for this?

> 
> Signed-off-by: Aatif Mushtaq <aatif4.m@...sung.com>
> ---
>  include/linux/dmaengine.h | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index b137fdb56093..8a73b2147983 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -833,6 +833,7 @@ struct dma_filter {
>   *	be called after period_len bytes have been transferred.
>   * @device_prep_interleaved_dma: Transfer expression in a generic way.
>   * @device_prep_dma_imm_data: DMA's 8 byte immediate data to the dst address
> + * @device_prep_2d_dma_memcpy: prepares a 2D memcpy operation
>   * @device_caps: May be used to override the generic DMA slave capabilities
>   *	with per-channel specific ones
>   * @device_config: Pushes a new configuration to a channel, return 0 or an error
> @@ -938,6 +939,9 @@ struct dma_device {
>  	struct dma_async_tx_descriptor *(*device_prep_dma_imm_data)(
>  		struct dma_chan *chan, dma_addr_t dst, u64 data,
>  		unsigned long flags);
> +	struct dma_async_tx_descriptor *(*device_prep_2d_dma_memcpy)(
> +		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> +		size_t len, u16 src_imm, u16 dest_imm, unsigned long flags);
>  
>  	void (*device_caps)(struct dma_chan *chan, struct dma_slave_caps *caps);
>  	int (*device_config)(struct dma_chan *chan, struct dma_slave_config *config);
> @@ -1087,6 +1091,27 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy(
>  						    len, flags);
>  }
>  
> +/**
> + * device_prep_2d_dma_memcpy() - Prepare a DMA 2D memcpy descriptor.
> + * @chan: The channel to be used for this descriptor
> + * @dest: Address of the destination data for a DMA channel
> + * @src: Address of the source data for a DMA channel
> + * @len: The total size of data
> + * @src_imm: The immediate value to be added to the src address register
> + * @dest_imm: The immediate value to be added to the dst address register
> + * @flags: DMA engine flags
> + */
> +static inline struct dma_async_tx_descriptor *device_prep_2d_dma_memcpy(
> +		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> +		size_t len, u16 src_imm, u16 dest_imm, unsigned long flags)
> +{
> +	if (!chan || !chan->device || !chan->device->device_prep_2d_dma_memcpy)
> +		return NULL;
> +
> +	return chan->device->device_prep_2d_dma_memcpy(chan, dest, src, len,
> +						       src_imm, dest_imm, flags);
> +}
> +
>  static inline bool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
>  		enum dma_desc_metadata_mode mode)
>  {
> -- 
> 2.17.1

-- 
~Vinod