linux-kernel - Re: [PATCH v2 1/3] dmaengine: add DMA_PREP

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Message-ID: <20170719100753.GF3053@localhost>
Date:   Wed, 19 Jul 2017 15:37:53 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Abhishek Sahu <absahu@...eaurora.org>
Cc:     andy.gross@...aro.org, david.brown@...aro.org,
        dan.j.williams@...el.com, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] dmaengine: add DMA_PREP_CMD for non-Data
 descriptors.

On Mon, Jun 26, 2017 at 06:19:27PM +0530, Abhishek Sahu wrote:
> Some of the DMA controllers are capable of issuing the commands
> to peripheral by the DMA. These commands can be list of register
> reads/writes and its different from normal data reads/writes.
> This patch adds new flag DMA_PREP_CMD in DMA API which tells
> the driver that the data passed to DMA API is in command format
> and DMA driver will form descriptor in the required format.
> 
> This flag can be used by any DMA controller driver which requires
> special handling for non-Data descriptors.

Please add Documentation for this new flag in Documentation/dmaengine/provider.txt

> 
> Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
> ---
>  include/linux/dmaengine.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 5336808..bbc297e 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -186,6 +186,8 @@ struct dma_interleaved_template {
>   *  on the result of this operation
>   * @DMA_CTRL_REUSE: client can reuse the descriptor and submit again till
>   *  cleared or freed
> + * @DMA_PREP_CMD: tell the driver that the data passed to DMA API is in command
> + *  format and it will be used for configuring the peripheral registers.

Can you explain what is command format..?

>   */
>  enum dma_ctrl_flags {
>  	DMA_PREP_INTERRUPT = (1 << 0),
> @@ -195,6 +197,7 @@ enum dma_ctrl_flags {
>  	DMA_PREP_CONTINUE = (1 << 4),
>  	DMA_PREP_FENCE = (1 << 5),
>  	DMA_CTRL_REUSE = (1 << 6),
> +	DMA_PREP_CMD = (1 << 7),
>  };
>  
>  /**
> -- 
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
> 

-- 
~Vinod