On Fri, 2014-03-14 at 23:20 +0530, Srikanth Thokala wrote:
> This is the driver for the AXI Video Direct Memory Access (AXI
> VDMA) core, which is a soft Xilinx IP core that provides high-
> bandwidth direct memory access between memory and AXI4-Stream
> type video target peripherals. The core provides efficient two
> dimensional DMA operations with independent asynchronous read
> and write channel operation.
>
> This module works on Zynq (ARM Based SoC) and Microblaze platforms.
Few comments below.
[]
> +++ b/drivers/dma/xilinx/xilinx_vdma.c
[]
> +/**
> + * xilinx_vdma_prep_slave_sg - prepare a descriptor for a DMA_SLAVE transaction
> + * @dchan: DMA channel
> + * @xt: Interleaved template pointer
> + * @flags: transfer ack flags
> + *
> + * Return: Async transaction descriptor on success and NULL on failure
> + */
> +static struct dma_async_tx_descriptor *
> +xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
> + struct dma_interleaved_template *xt,
> + unsigned long flags)
> +{
> + struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
> + struct xilinx_vdma_tx_descriptor *desc;
> + struct xilinx_vdma_tx_segment *segment, *prev = NULL;
> + struct xilinx_vdma_desc_hw *hw;
> +
> + if ((xt->dir != DMA_MEM_TO_DEV) && (xt->dir != DMA_DEV_TO_MEM))
> + return NULL;
!is_slave_direction()
[]
> +static int xilinx_vdma_chan_probe(struct xilinx_vdma_device *xdev,
> + struct device_node *node)
> +{
> + struct xilinx_vdma_chan *chan;
> + bool has_dre = false;
> + u32 value, width;
> + int err;
[]
> + width = value >> 3; /* Convert bits to bytes */
> +
> + /* If data width is greater than 8 bytes, DRE is not in hw */
> + if (width > 8)
> + has_dre = false;
> +
> + if (!has_dre)
> + xdev->common.copy_align = fls(width - 1);
Is width power of two? For me looks like it should be fls(width) - 1;
So, device can't work with alignment less than defined in this case,
correct?
[]
> +/**
> + * xilinx_vdma_probe - Driver probe function
> + * @pdev: Pointer to the platform_device structure
> + *
> + * Return: '0' on success and failure value on error
> + */
> +static int xilinx_vdma_probe(struct platform_device *pdev)
> +{
> + struct device_node *node = pdev->dev.of_node;
> + struct xilinx_vdma_device *xdev;
> + struct device_node *child;
> + struct resource *io;
> + u32 num_frames;
> + int i, err;
> +
> + dev_info(&pdev->dev, "Probing xilinx axi vdma engine\n");
dev_dbg? Or move this to the end of function and change text to
something like "Probed ..."
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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