RE: [PATCH 1/3] dmaengine: Add support for 2D DMA operation

["Aatif Mushtaq/Aatif Mushtaq" <aatif4.m@samsung.com>]

> -----Original Message-----
> From: Vinod Koul <vkoul@kernel.org>
> Sent: 27 February 2025 13:32
> To: Aatif Mushtaq <aatif4.m@samsung.com>
> Cc: dmaengine@vger.kernel.org; linux-kernel@vger.kernel.org;
> pankaj.dubey@samsung.com; aswani.reddy@samsung.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?
> 

Thanks for pointing out, interleaved API can be used for this.
I will make the change

> >
> > Signed-off-by: Aatif Mushtaq <aatif4.m@samsung.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