linux-kernel - [PATCH 07/12] bcm2835-dma: Support dma flags for multi-beat burst

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Message-ID: <570953f9532e2dc46568674d3c1348cdf26488b6.1706948717.git.andrea.porta@suse.com>
Date: Sun,  4 Feb 2024 07:59:35 +0100
From: Andrea della Porta <andrea.porta@...e.com>
To: Vinod Koul <vkoul@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	dmaengine@...r.kernel.org,
	linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Maxime Ripard <maxime@...no.tech>,
	Dom Cobley <popcornmix@...il.com>,
	Phil Elwell <phil@...pberrypi.com>,
	Andrea della Porta <andrea.porta@...e.com>
Subject: [PATCH 07/12] bcm2835-dma: Support dma flags for multi-beat burst

From: Dom Cobley <popcornmix@...il.com>

Add a control bit to enable a multi-beat burst on a DMA.
This improves DMA performance and is required for HDMI audio.

Signed-off-by: Dom Cobley <popcornmix@...il.com>
Signed-off-by: Andrea della Porta <andrea.porta@...e.com>
---
 drivers/dma/bcm2835-dma.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index d8d1f9ba2572..a20700a400a2 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -156,7 +156,8 @@ struct bcm2835_desc {
 #define BCM2835_DMA_S_WIDTH	BIT(9) /* 128bit writes if set */
 #define BCM2835_DMA_S_DREQ	BIT(10) /* enable SREQ for source */
 #define BCM2835_DMA_S_IGNORE	BIT(11) /* ignore source reads - read 0 */
-#define BCM2835_DMA_BURST_LENGTH(x) ((x & 15) << 12)
+#define BCM2835_DMA_BURST_LENGTH(x) (((x) & 15) << 12)
+#define BCM2835_DMA_GET_BURST_LENGTH(x) (((x) >> 12) & 15)
 #define BCM2835_DMA_CS_FLAGS(x) ((x) & (BCM2835_DMA_PRIORITY(15) | \
 				      BCM2835_DMA_PANIC_PRIORITY(15) | \
 				      BCM2835_DMA_WAIT_FOR_WRITES | \
@@ -180,6 +181,11 @@ struct bcm2835_desc {
 #define WIDE_DEST(x) (((x) & BCM2835_DMA_WIDE_DEST) ? \
 		      BCM2835_DMA_D_WIDTH : 0)
 
+/* A fake bit to request that the driver requires multi-beat burst */
+#define BCM2835_DMA_BURST BIT(30)
+#define BURST_LENGTH(x) (((x) & BCM2835_DMA_BURST) ? \
+			 BCM2835_DMA_BURST_LENGTH(3) : 0)
+
 /* debug register bits */
 #define BCM2835_DMA_DEBUG_LAST_NOT_SET_ERR	BIT(0)
 #define BCM2835_DMA_DEBUG_FIFO_ERR		BIT(1)
@@ -282,7 +288,7 @@ struct bcm2835_desc {
 /* the max dma length for different channels */
 #define MAX_DMA40_LEN SZ_1G
 
-#define BCM2711_DMA40_BURST_LEN(x)	((min(x, 16) - 1) << 8)
+#define BCM2711_DMA40_BURST_LEN(x)	(((x) & 15) << 8)
 #define BCM2711_DMA40_INC		BIT(12)
 #define BCM2711_DMA40_SIZE_32		(0 << 13)
 #define BCM2711_DMA40_SIZE_64		(1 << 13)
@@ -359,12 +365,16 @@ static inline uint32_t to_bcm2711_ti(uint32_t info)
 
 static inline uint32_t to_bcm2711_srci(uint32_t info)
 {
-	return ((info & BCM2835_DMA_S_INC) ? BCM2711_DMA40_INC : 0);
+	return ((info & BCM2835_DMA_S_INC) ? BCM2711_DMA40_INC : 0) |
+	       ((info & BCM2835_DMA_S_WIDTH) ? BCM2711_DMA40_SIZE_128 : 0) |
+	       BCM2711_DMA40_BURST_LEN(BCM2835_DMA_GET_BURST_LENGTH(info));
 }
 
 static inline uint32_t to_bcm2711_dsti(uint32_t info)
 {
-	return ((info & BCM2835_DMA_D_INC) ? BCM2711_DMA40_INC : 0);
+	return ((info & BCM2835_DMA_D_INC) ? BCM2711_DMA40_INC : 0) |
+	       ((info & BCM2835_DMA_D_WIDTH) ? BCM2711_DMA40_SIZE_128 : 0) |
+	       BCM2711_DMA40_BURST_LEN(BCM2835_DMA_GET_BURST_LENGTH(info));
 }
 
 static inline uint32_t to_bcm2711_cbaddr(dma_addr_t addr)
@@ -933,7 +943,8 @@ 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_D_INC | BCM2835_DMA_S_INC |
-		   WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
+		   WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) |
+		   WIDE_DEST(c->dreq) | BURST_LENGTH(c->dreq);
 	u32 extra = BCM2835_DMA_INT_EN;
 	size_t max_len = bcm2835_dma_max_frame_length(c);
 	size_t frames;
@@ -964,8 +975,8 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
 	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 	struct bcm2835_desc *d;
 	dma_addr_t src = 0, dst = 0;
-	u32 info = WAIT_RESP(c->dreq) |
-		   WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
+	u32 info = WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) |
+		   WIDE_DEST(c->dreq) | BURST_LENGTH(c->dreq);
 	u32 extra = BCM2835_DMA_INT_EN;
 	size_t frames;
 
@@ -1017,7 +1028,8 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 	struct bcm2835_desc *d;
 	dma_addr_t src, dst;
-	u32 info = WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
+	u32 info = WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) |
+		   WIDE_DEST(c->dreq) | BURST_LENGTH(c->dreq);
 	u32 extra = 0;
 	size_t max_len = bcm2835_dma_max_frame_length(c);
 	size_t frames;
-- 
2.41.0