On 06/08/2020 08:30, Rajesh Gumasta wrote:
> Adding GPC DMA controller driver for Tegra186 and Tegra194. The driver
> supports dma transfers between memory to memory, IO peripheral to memory
> and memory to IO peripheral.
>
> Signed-off-by: Pavan Kunapuli <pkunapuli@xxxxxxxxxx>
> Signed-off-by: Rajesh Gumasta <rgumasta@xxxxxxxxxx>
> ---
> drivers/dma/Kconfig | 12 +
> drivers/dma/Makefile | 1 +
> drivers/dma/tegra-gpc-dma.c | 1472 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 1485 insertions(+)
> create mode 100644 drivers/dma/tegra-gpc-dma.c
...
> +static void tdc_start_head_req(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_sg_req *sg_req;
> + struct virt_dma_desc *vdesc;
> +
> + if (list_empty(&tdc->pending_sg_req))
> + return;
> +
> + if (tdc->is_pending)
> + return;
> +
> + vdesc = vchan_next_desc(&tdc->vc);
> + if (!vdesc)
> + return;
> + list_del(&vdesc->node);
> + tdc->dma_desc = vd_to_tegra_dma_desc(vdesc);
> + tdc->is_pending = true;
> + tdc->dma_desc->tdc = tdc;
> + sg_req = list_first_entry(&tdc->pending_sg_req,
> + typeof(*sg_req), node);
> + tegra_dma_start(tdc, sg_req);
> + sg_req->configured = true;
> + tdc->busy = true;
> +}
I really don't understand this. First we get a descriptor for the
vchan_next_desc and then we get a sg_req from another list. I really
don't see why we need to have two lists here. Seems overly complicated.
Jon
--
nvpublic
