Re: [PATCH v2 1/3] dmaengine: add DMA_PREP_CMD for non-Data descriptors.

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On 2017-07-31 18:04, Vinod Koul wrote:
On Fri, Jul 28, 2017 at 09:38:56PM +0530, Abhishek Sahu wrote:
On 2017-07-19 17:48, Abhishek Sahu wrote:
>On 2017-07-19 15:37, Vinod Koul wrote:
>>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
>>
>
> Sure. I will add update the documentation in v3.
>
>>>
>>>Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
>>>---
>>> 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..?
>>
>
> The command format is not generic and its format will be dependent
> upon DMA engine. The client drivers will give data in its own
> command formats and this flag will be passed to DMA API’s to do
> the parsing according to its own command format.
>
> Currently this flag description and name is inclined towards
> Qualcomm BAM DMA command flag. We want to make this flag as
> generic one so require your suggestion regarding this.
> Will renaming this flag as DMA_PREP_NON_DATA or
> DMA_PREP_CUSTOM make it more generic?
>

 can we use same flag name DMA_PREP_CMD or should we
 go for some other name?

Are you asking for using DMA_PREP_CMD, for that I think should be ok

If you asking about adding a new flag with DMA_PREP_CMD, then it would no


 Thanks Vinod.

 We just want to add only one flag with name DMA_PREP_CMD and no
 other new flag.

 I will update the description for DMA_PREP_CMD in
 Documentation/dmaengine/provider.txt


>>>  */
>>> 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),
>>> };
>>>

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