Re: [PATCH v2 1/1] dmaengine: qcom: bam_dma: Add support for metadata

[Vinod Koul <vkoul@kernel.org>]

On 27-10-22, 10:50, Sireesh Kodali wrote:
> From: Vladimir Lypak <vladimir.lypak@gmail.com>
> 
> Add client metadata support for receiving information about transfers.
> Only type of metadata implemented is amount of transferred bytes. This
> can be used to know how much data is actually received if information
> transferred doesn't contain header with size or is aggregated.
> 
> Signed-off-by: Vladimir Lypak <vladimir.lypak@gmail.com>
> Signed-off-by: Sireesh Kodali <sireeshkodali1@gmail.com>
> ---
>  drivers/dma/qcom/bam_dma.c       | 57 ++++++++++++++++++++++++++++++++
>  include/linux/dma/qcom_bam_dma.h |  8 +++++
>  2 files changed, 65 insertions(+)
> 
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 3135a3e4a167..264a9a2e199f 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -30,6 +30,7 @@
>  #include <linux/module.h>
>  #include <linux/interrupt.h>
>  #include <linux/dma-mapping.h>
> +#include <linux/dma/qcom_bam_dma.h>
>  #include <linux/scatterlist.h>
>  #include <linux/device.h>
>  #include <linux/platform_device.h>
> @@ -70,6 +71,7 @@ struct bam_async_desc {
>  	u16 flags;
>  
>  	struct bam_desc_hw *curr_desc;
> +	struct bam_dma_metadata *metadata;
>  
>  	/* list node for the desc in the bam_chan list of descriptors */
>  	struct list_head desc_node;
> @@ -418,6 +420,52 @@ static inline void __iomem *bam_addr(struct bam_device *bdev, u32 pipe,
>  		r.ee_mult * bdev->ee;
>  }
>  
> +/**
> + * bam_update_metadata - update metadata buffer
> + * @bchan: BAM channel to read metadata from
> + * @async_desc: BAM async descriptior
> + *
> + * Updates metadata buffer (transfer size) based on values
> + * read from FIFO descriptors at bchan->head
> + */
> +
> +static inline void bam_update_metadata(struct bam_chan *bchan,
> +				       struct bam_async_desc *async_desc)
> +{
> +	unsigned int i, e, len = 0;
> +	struct bam_desc_hw *fifo;
> +
> +	if (!async_desc->metadata)
> +		return;
> +
> +	fifo = PTR_ALIGN(bchan->fifo_virt, sizeof(struct bam_desc_hw));
> +	for (i = bchan->head, e = i + async_desc->xfer_len; i < e; i++)
> +		len += fifo[i % MAX_DESCRIPTORS].size;
> +
> +	async_desc->metadata->xfer_len_bytes += len;
> +}
> +
> +/**
> + * bam_attach_metadata - attach metadata buffer to the async descriptor
> + * @desc: async descriptor
> + * @data: buffer pointer
> + * @len: length of passed buffer
> + */
> +static int bam_attach_metadata(struct dma_async_tx_descriptor *desc, void *data,
> +			       size_t len)
> +{
> +	struct bam_async_desc *async_desc;
> +
> +	if (!data || len != sizeof(struct bam_dma_metadata))
> +		return -EINVAL;
> +
> +	async_desc = container_of(desc, struct bam_async_desc, vd.tx);
> +	async_desc->metadata = data;
> +	async_desc->metadata->xfer_len_bytes = 0;
> +
> +	return 0;
> +}
> +
>  /**
>   * bam_reset() - reset and initialize BAM registers
>   * @bdev: bam device
> @@ -456,6 +504,10 @@ static void bam_reset(struct bam_device *bdev)
>  	writel_relaxed(BAM_IRQ_MSK, bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));
>  }
>  
> +static struct dma_descriptor_metadata_ops metadata_ops = {
> +	.attach = bam_attach_metadata,
> +};
> +
>  /**
>   * bam_reset_channel - Reset individual BAM DMA channel
>   * @bchan: bam channel
> @@ -714,6 +766,8 @@ static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
>  		} while (remainder > 0);
>  	}
>  
> +	async_desc->vd.tx.metadata_ops = &metadata_ops;
> +
>  	return vchan_tx_prep(&bchan->vc, &async_desc->vd, flags);
>  }
>  
> @@ -867,6 +921,8 @@ static u32 process_channel_irqs(struct bam_device *bdev)
>  			if (avail < async_desc->xfer_len)
>  				break;
>  
> +			bam_update_metadata(bchan, async_desc);
> +
>  			/* manage FIFO */
>  			bchan->head += async_desc->xfer_len;
>  			bchan->head %= MAX_DESCRIPTORS;
> @@ -1347,6 +1403,7 @@ static int bam_dma_probe(struct platform_device *pdev)
>  	bdev->common.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
>  	bdev->common.src_addr_widths = DMA_SLAVE_BUSWIDTH_4_BYTES;
>  	bdev->common.dst_addr_widths = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +	bdev->common.desc_metadata_modes = DESC_METADATA_CLIENT;
>  	bdev->common.device_alloc_chan_resources = bam_alloc_chan;
>  	bdev->common.device_free_chan_resources = bam_free_chan;
>  	bdev->common.device_prep_slave_sg = bam_prep_slave_sg;
> diff --git a/include/linux/dma/qcom_bam_dma.h b/include/linux/dma/qcom_bam_dma.h
> index 68fc0e643b1b..8168b0573f45 100644
> --- a/include/linux/dma/qcom_bam_dma.h
> +++ b/include/linux/dma/qcom_bam_dma.h
> @@ -8,6 +8,14 @@
>  
>  #include <asm/byteorder.h>
>  
> +/*
> + * This data type is used as client metadata buffer in bam driver.
> + */
> +struct bam_dma_metadata {
> +	/* Actual number of bytes transferred by hardware */
> +	size_t xfer_len_bytes;

Pls implement dmaengine_result() and report that with proper residue
set...

Thanks

-- 
~Vinod