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

[Abhishek Sahu]

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 APIâs 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),
> > >>> };
> > >>>