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

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Message-Id: <2d8c24359b2daa32ce0597a2949b7b2bebaf23de.1659211633.git.christophe.jaillet@wanadoo.fr>
Date:   Sat, 30 Jul 2022 22:07:45 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Vinod Koul <vkoul@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        dmaengine@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] dmaengine: stm32-dmamux: Simplify code and save a few bytes of memory

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@...adoo.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