[PATCH] dmaengine: stm32-dmamux: Simplify code and save a few bytes of memory

[PATCH] dmaengine: stm32-dmamux: Simplify code and save a few bytes of memory

[Christophe JAILLET]

STM32_DMAMUX_MAX_DMA_REQUESTS is small (i.e. 32) and when the 'dma_inuse'
bitmap is allocated, there is already a check that 'dma_req' is <= this
limit.

So, there is no good reason to dynamically allocate this bitmap. This
just waste some memory and some cycles.

Use DECLARE_BITMAP with the maximum bitmap size instead.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/dma/stm32-dmamux.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c
index eee0c5aa5fb5..212c332f14f9 100644
--- a/drivers/dma/stm32-dmamux.c
+++ b/drivers/dma/stm32-dmamux.c
@@ -39,7 +39,7 @@ struct stm32_dmamux_data {
 	u32 dma_requests; /* Number of DMA requests connected to DMAMUX */
 	u32 dmamux_requests; /* Number of DMA requests routed toward DMAs */
 	spinlock_t lock; /* Protects register access */
-	unsigned long *dma_inuse; /* Used DMA channel */
+	DECLARE_BITMAP(dma_inuse, STM32_DMAMUX_MAX_DMA_REQUESTS); /* Used DMA channel */
 	u32 ccr[STM32_DMAMUX_MAX_DMA_REQUESTS]; /* Used to backup CCR register
 						 * in suspend
 						 */
@@ -229,12 +229,6 @@ static int stm32_dmamux_probe(struct platform_device *pdev)
 
 	stm32_dmamux->dma_requests = dma_req;
 	stm32_dmamux->dma_reqs[0] = count;
-	stm32_dmamux->dma_inuse = devm_kcalloc(&pdev->dev,
-					       BITS_TO_LONGS(dma_req),
-					       sizeof(unsigned long),
-					       GFP_KERNEL);
-	if (!stm32_dmamux->dma_inuse)
-		return -ENOMEM;
 
 	if (device_property_read_u32(&pdev->dev, "dma-requests",
 				     &stm32_dmamux->dmamux_requests)) {
-- 
2.34.1

Re: [PATCH] dmaengine: stm32-dmamux: Simplify code and save a few bytes of memory

[Vinod Koul]

On 30-07-22, 22:07, Christophe JAILLET wrote:
> STM32_DMAMUX_MAX_DMA_REQUESTS is small (i.e. 32) and when the 'dma_inuse'
> bitmap is allocated, there is already a check that 'dma_req' is <= this
> limit.
> 
> So, there is no good reason to dynamically allocate this bitmap. This
> just waste some memory and some cycles.
> 
> Use DECLARE_BITMAP with the maximum bitmap size instead.

Applied, thanks

-- 
~Vinod