Re: [PATCH 05/18] dmaengine: bcm2835: move CB final extra info generation into function

Frank Li
2024-06-05T16:19:06Z

On Fri, May 24, 2024 at 07:26:49PM +0100, Dave Stevenson wrote:
> From: Stefan Wahren <stefan.wahren@i2se.com>
>
> Similar to the info generation, generate the final extra info with a
> separate function. This is necessary to introduce other platforms
> with different info bits.

Each patch commit is independent.

Introduce common help function to generate the final extra info to reduce
duplicate codes in each DMA operation.

>
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> ---
> drivers/dma/bcm2835-dma.c | 34 ++++++++++++++++++++++++++++------
> 1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index 7cef7ff89575..ef452ebb3c15 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -229,6 +229,29 @@ static u32 bcm2835_dma_prepare_cb_info(struct bcm2835_chan *c,
> return result;
> }
>
> +static u32 bcm2835_dma_prepare_cb_extra(struct bcm2835_chan *c,
> + enum dma_transfer_direction direction,
> + bool cyclic, bool final,
> + unsigned long flags)
> +{
> + u32 result = 0;
> +
> + if (cyclic) {
> + if (flags & DMA_PREP_INTERRUPT)
> + result |= BCM2835_DMA_INT_EN;
> + } else {
> + if (!final)
> + return 0;
> +
> + result |= BCM2835_DMA_INT_EN;
> +
> + if (direction == DMA_MEM_TO_MEM)
> + result |= BCM2835_DMA_WAIT_RESP;
> + }

move if (direction == DMA_MEM_TO_MEM) outof else branch.
DMA_MEM_TO_MEM is impossible for cyclic. Reduce if level can help
easy to follow up.

if (cyclic)
...
else
...

if (direction == DMA_MEM_TO_MEM)
result |= BCM2835_DMA_WAIT_RESP;

> +
> + return result;
> +}
> +
> static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc)
> {
> size_t i;
> @@ -644,7 +667,8 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_memcpy(
> struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> struct bcm2835_desc *d;
> u32 info = bcm2835_dma_prepare_cb_info(c, DMA_MEM_TO_MEM, false);
> - u32 extra = BCM2835_DMA_INT_EN | BCM2835_DMA_WAIT_RESP;
> + u32 extra = bcm2835_dma_prepare_cb_extra(c, DMA_MEM_TO_MEM, false,
> + true, 0);
> size_t max_len = bcm2835_dma_max_frame_length(c);
> size_t frames;
>
> @@ -675,7 +699,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
> struct bcm2835_desc *d;
> dma_addr_t src = 0, dst = 0;
> u32 info = bcm2835_dma_prepare_cb_info(c, direction, false);
> - u32 extra = BCM2835_DMA_INT_EN;
> + u32 extra = bcm2835_dma_prepare_cb_extra(c, direction, false, true, 0);
> size_t frames;
>
> if (!is_slave_direction(direction)) {
> @@ -723,7 +747,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
> dma_addr_t src, dst;
> u32 info = bcm2835_dma_prepare_cb_info(c, direction,
> buf_addr == od->zero_page);
> - u32 extra = 0;
> + u32 extra = bcm2835_dma_prepare_cb_extra(c, direction, true, true, 0);
> size_t max_len = bcm2835_dma_max_frame_length(c);
> size_t frames;
>
> @@ -739,9 +763,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
> return NULL;
> }
>
> - if (flags & DMA_PREP_INTERRUPT)
> - extra |= BCM2835_DMA_INT_EN;
> - else
> + if (!(flags & DMA_PREP_INTERRUPT))
> period_len = buf_len;
>
> /*
> --
> 2.34.1
>