Re: [PATCH v2 4/5] PCI: epf-mhi: Add batched DMA read support

[Manivannan Sadhasivam]

On Tue, Sep 15, 2026 at 10:42:39AM +0530, Sumit Kumar wrote:
> 
> 
> On 8/14/2026 8:22 PM, Manivannan Sadhasivam wrote:
> > On Thu, Aug 06, 2026 at 12:11:34PM -0500, Frank Li wrote:
> > 
> > [...]
> > 
> > > > +       config.direction = DMA_DEV_TO_MEM;
> > > > +       ret = dmaengine_slave_config(chan, &config);
> > > > +       if (ret) {
> > > > +               dev_err(dev, "Failed to configure DMA channel for %u-buffer batch read: %d\n",
> > > > +                       num_buffers, ret);
> > > > +               goto err_unmap;
> > > > +       }
> > > > +
> > > > +       desc = dmaengine_prep_dma_sg(chan, dst_sg, num_buffers,
> > > > +                                    src_sg, num_buffers,
> > > > +                                    DMA_CTRL_ACK | DMA_PREP_INTERRUPT);
> > > Although both side memory address, but as previous discussion, which is not
> > > memcpy, still memory to IO space transfer.
> > > 
> > I agree, it is peripheral DMA nevertheless.
> > 
> > > Maybe enhence device_prep_peripheral_dma_vec(). Actually eDMA still split
> > > it to small trunk and linked together.
> > > 
> > By enhance you mean keeping the semantics of device_prep_peripheral_dma_vec()
> > API? I don't know how it helps because we would most likely end up with two
> > vector arguments and duplicating scatter-gather lists.
> Frank can you comment on this.

Frank, ping!

- Mani

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