[PATCH] dmaengine: qcom_bam_dma: Add descriptor flags

[PATCH] dmaengine: qcom_bam_dma: Add descriptor flags

[Andy Gross]

This patch adds support for end of transaction (EOT) and notify when done (NWD)
hardware descriptor flags.

The EOT flag requests that the peripheral assert an end of transaction interrupt
when that descriptor is complete.  It also results in special signaling protocol
that is used between the attached peripheral and the core using the DMA
controller.  Clients will specify DMA_PREP_INTERRUPT to enable this flag.

The NWD flag requests that the peripheral wait until the data has been fully
processed by the peripheral before moving on to the next descriptor.  Clients
will specify DMA_PREP_FENCE to enable this flag.

Signed-off-by: Andy Gross <agross@codeaurora.org>
---
 drivers/dma/qcom_bam_dma.c |   20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/qcom_bam_dma.c b/drivers/dma/qcom_bam_dma.c
index e01c2d106..4635224 100644
--- a/drivers/dma/qcom_bam_dma.c
+++ b/drivers/dma/qcom_bam_dma.c
@@ -61,12 +61,17 @@ struct bam_desc_hw {
 #define DESC_FLAG_INT BIT(15)
 #define DESC_FLAG_EOT BIT(14)
 #define DESC_FLAG_EOB BIT(13)
+#define DESC_FLAG_NWD BIT(12)
 
 struct bam_async_desc {
 	struct virt_dma_desc vd;
 
 	u32 num_desc;
 	u32 xfer_len;
+
+	/* transaction flags, EOT|EOB|NWD */
+	u16 flags;
+
 	struct bam_desc_hw *curr_desc;
 
 	enum dma_transfer_direction dir;
@@ -490,6 +495,14 @@ static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
 	if (!async_desc)
 		goto err_out;
 
+	if (flags & DMA_PREP_FENCE)
+		async_desc->flags |= DESC_FLAG_NWD;
+
+	if (flags & DMA_PREP_INTERRUPT)
+		async_desc->flags |= DESC_FLAG_EOT;
+	else
+		async_desc->flags |= DESC_FLAG_INT;
+
 	async_desc->num_desc = num_alloc;
 	async_desc->curr_desc = async_desc->desc;
 	async_desc->dir = direction;
@@ -795,8 +808,11 @@ static void bam_start_dma(struct bam_chan *bchan)
 	else
 		async_desc->xfer_len = async_desc->num_desc;
 
-	/* set INT on last descriptor */
-	desc[async_desc->xfer_len - 1].flags |= DESC_FLAG_INT;
+	/* set any special flags on the last descriptor */
+	if (async_desc->num_desc == async_desc->xfer_len)
+		desc[async_desc->xfer_len - 1].flags = async_desc->flags;
+	else
+		desc[async_desc->xfer_len - 1].flags |= DESC_FLAG_INT;
 
 	if (bchan->tail + async_desc->xfer_len > MAX_DESCRIPTORS) {
 		u32 partial = MAX_DESCRIPTORS - bchan->tail;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

[PATCH] dmaengine: qcom_bam_dma: Add descriptor flags

[Vinod Koul]

On Fri, May 30, 2014 at 03:49:50PM -0500, Andy Gross wrote:
> This patch adds support for end of transaction (EOT) and notify when done (NWD)
> hardware descriptor flags.
> 
> The EOT flag requests that the peripheral assert an end of transaction interrupt
> when that descriptor is complete.  It also results in special signaling protocol
> that is used between the attached peripheral and the core using the DMA
> controller.  Clients will specify DMA_PREP_INTERRUPT to enable this flag.
> 
> The NWD flag requests that the peripheral wait until the data has been fully
> processed by the peripheral before moving on to the next descriptor.  Clients
> will specify DMA_PREP_FENCE to enable this flag.

I am going to apply this, but pls send a follow up patch to add comments on the
flags and their behaviour. I think it is required!

> 
> Signed-off-by: Andy Gross <agross@codeaurora.org>
> ---
>  drivers/dma/qcom_bam_dma.c |   20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/qcom_bam_dma.c b/drivers/dma/qcom_bam_dma.c
> index e01c2d106..4635224 100644
> --- a/drivers/dma/qcom_bam_dma.c
> +++ b/drivers/dma/qcom_bam_dma.c
> @@ -61,12 +61,17 @@ struct bam_desc_hw {
>  #define DESC_FLAG_INT BIT(15)
>  #define DESC_FLAG_EOT BIT(14)
>  #define DESC_FLAG_EOB BIT(13)
> +#define DESC_FLAG_NWD BIT(12)
explaining behvaiour will help..

-- 
~Vinod

>  
>  struct bam_async_desc {
>  	struct virt_dma_desc vd;
>  
>  	u32 num_desc;
>  	u32 xfer_len;
> +
> +	/* transaction flags, EOT|EOB|NWD */
> +	u16 flags;
> +
>  	struct bam_desc_hw *curr_desc;
>  
>  	enum dma_transfer_direction dir;
> @@ -490,6 +495,14 @@ static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
>  	if (!async_desc)
>  		goto err_out;
>  
> +	if (flags & DMA_PREP_FENCE)
> +		async_desc->flags |= DESC_FLAG_NWD;
> +
> +	if (flags & DMA_PREP_INTERRUPT)
> +		async_desc->flags |= DESC_FLAG_EOT;
> +	else
> +		async_desc->flags |= DESC_FLAG_INT;
> +
>  	async_desc->num_desc = num_alloc;
>  	async_desc->curr_desc = async_desc->desc;
>  	async_desc->dir = direction;
> @@ -795,8 +808,11 @@ static void bam_start_dma(struct bam_chan *bchan)
>  	else
>  		async_desc->xfer_len = async_desc->num_desc;
>  
> -	/* set INT on last descriptor */
> -	desc[async_desc->xfer_len - 1].flags |= DESC_FLAG_INT;
> +	/* set any special flags on the last descriptor */
> +	if (async_desc->num_desc == async_desc->xfer_len)
> +		desc[async_desc->xfer_len - 1].flags = async_desc->flags;
> +	else
> +		desc[async_desc->xfer_len - 1].flags |= DESC_FLAG_INT;
>  
>  	if (bchan->tail + async_desc->xfer_len > MAX_DESCRIPTORS) {
>  		u32 partial = MAX_DESCRIPTORS - bchan->tail;
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
> 
> --
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-- 

[PATCH] dmaengine: qcom_bam_dma: Add descriptor flags

[Andy Gross]

On Mon, Jul 14, 2014 at 10:06:16PM +0530, Vinod Koul wrote:
> On Fri, May 30, 2014 at 03:49:50PM -0500, Andy Gross wrote:
> > This patch adds support for end of transaction (EOT) and notify when done (NWD)
> > hardware descriptor flags.
> > 
> > The EOT flag requests that the peripheral assert an end of transaction interrupt
> > when that descriptor is complete.  It also results in special signaling protocol
> > that is used between the attached peripheral and the core using the DMA
> > controller.  Clients will specify DMA_PREP_INTERRUPT to enable this flag.
> > 
> > The NWD flag requests that the peripheral wait until the data has been fully
> > processed by the peripheral before moving on to the next descriptor.  Clients
> > will specify DMA_PREP_FENCE to enable this flag.
> 
> I am going to apply this, but pls send a follow up patch to add comments on the
> flags and their behaviour. I think it is required!

Will do.

<snip>

> >  #define DESC_FLAG_EOT BIT(14)
> >  #define DESC_FLAG_EOB BIT(13)
> > +#define DESC_FLAG_NWD BIT(12)
> explaining behvaiour will help..

In the followup, I'll put in a lengthy description of the INT/EOT/NWD and how
they are used in the signaling to/from the attached peripheral.


Thanks!

-- 
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation