RE: [RFC] dmaengine: Add metadat_ops for dma_async_tx_descriptor

[Radhey Shyam Pandey <radheys@xilinx.com>]

> -----Original Message-----
> From: Peter Ujfalusi [mailto:peter.ujfalusi@ti.com]
> Sent: Friday, June 1, 2018 3:54 PM
> To: Radhey Shyam Pandey <radheys@xilinx.com>; vinod.koul@intel.com
> Cc: lars@metafoo.de; michal.simek@xilinx.com; linux-
> kernel@vger.kernel.org; dmaengine@vger.kernel.org;
> dan.j.williams@intel.com; Appana Durga Kedareswara Rao
> <appanad@xilinx.com>; linux-arm-kernel@lists.infradead.org
> Subject: [RFC] dmaengine: Add metadat_ops for dma_async_tx_descriptor
> 
> If the DMA supports per descriptor metadata it can implement the attach,
> get_ptr/set_len callbacks.
> 
> Client drivers must only use either attach or get_ptr/set_len to avoid
> miss configuration.
> 
> Wrappers are also added for the metadata_ops:
> dmaengine_desc_attach_metadata()
> dmaengine_desc_get_metadata_ptr()
> dmaengine_desc_set_metadata_len()
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
> Hi,
> 
> since attachments are bouncing back, I send the patch separately
> 
> Regards,
> Peter
> 
>  include/linux/dmaengine.h | 50
> +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 51fbb861e84b..ac42ace36aa3 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -491,6 +491,18 @@ struct dmaengine_unmap_data {
>  	dma_addr_t addr[0];
>  };
> 
> +struct dma_async_tx_descriptor;
> +
> +struct dma_descriptor_metadata_ops {
> +	int (*attach)(struct dma_async_tx_descriptor *desc, void *data,
> +		      size_t len);
> +
> +	void *(*get_ptr)(struct dma_async_tx_descriptor *desc,
> +			 size_t *payload_len, size_t *max_len);
> +	int (*set_len)(struct dma_async_tx_descriptor *desc,
> +		       size_t payload_len);
> +};
> +
>  /**
>   * struct dma_async_tx_descriptor - async transaction descriptor
>   * ---dma generic offload fields---
> @@ -520,6 +532,7 @@ struct dma_async_tx_descriptor {
>  	dma_async_tx_callback_result callback_result;
>  	void *callback_param;
>  	struct dmaengine_unmap_data *unmap;
> +	struct dma_descriptor_metadata_ops *metadata_ops;
>  #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
>  	struct dma_async_tx_descriptor *next;
>  	struct dma_async_tx_descriptor *parent;
> @@ -932,6 +945,43 @@ static inline struct dma_async_tx_descriptor
> *dmaengine_prep_dma_memcpy(
>  						    len, flags);
>  }
> 
> +static inline int dmaengine_desc_attach_metadata(
> +		struct dma_async_tx_descriptor *desc, void *data, size_t
> len)
> +{
> +	if (!desc)
> +		return 0;
> +
> +	if (!desc->metadata_ops || !desc->metadata_ops->attach)
> +		return -ENOTSUPP;
> +
> +	return desc->metadata_ops->attach(desc, data, len);
> +}
> +
> +static inline void *dmaengine_desc_get_metadata_ptr(
> +		struct dma_async_tx_descriptor *desc, size_t *payload_len,
> +		size_t *max_len)
> +{
> +	if (!desc)
> +		return NULL;
> +
> +	if (!desc->metadata_ops || !desc->metadata_ops->get_ptr)
> +		return ERR_PTR(-ENOTSUPP);
> +
> +	return desc->metadata_ops->get_ptr(desc, payload_len, max_len);
> +}
> +
> +static inline int dmaengine_desc_set_metadata_len(
> +		struct dma_async_tx_descriptor *desc, size_t payload_len)
> +{
> +	if (!desc)
> +		return 0;
> +
> +	if (!desc->metadata_ops || !desc->metadata_ops->set_len)
> +		return -ENOTSUPP;
> +
> +	return desc->metadata_ops->set_len(desc, payload_len);
> +}
> +
Thanks for the RFC patchset. It looks fine to me. We also need to update
documentation. Let's wait for Vinod/Lars feedback.

>  /**
>   * dmaengine_terminate_all() - Terminate all active DMA transfers
>   * @chan: The channel for which to terminate the transfers
> --
> Peter
> 
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