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

[Sumit Kumar <sumit.kumar@oss.qualcomm.com>]

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.
> - Mani
>