[PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Miquel Raynal]

Hello,

Following the introduction of scatter-gather support of Xilinx's XDMA IP
in the Linux kernel, here is a small series adding cyclic transfers.

The first patch is a real bug fix which triggered in my case, the second
just fixes a typo, the third one is a preparation patch to ease the
review of the fourth one which actually adds cyclic transfers support.

Thanks,
Miquèl

Miquel Raynal (4):
  dmaengine: xilinx: xdma: Fix interrupt vector setting
  dmaengine: xilinx: xdma: Fix typo
  dmaengine: xilinx: xdma: Prepare the introduction of cyclic transfers
  dmaengine: xilinx: xdma: Support cyclic transfers

 drivers/dma/xilinx/xdma-regs.h |   2 +
 drivers/dma/xilinx/xdma.c      | 190 +++++++++++++++++++++++++++++++--
 2 files changed, 183 insertions(+), 9 deletions(-)

-- 
2.34.1

[PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Miquel Raynal]

Hello,

Following the introduction of scatter-gather support of Xilinx's XDMA IP
in the Linux kernel, here is a small series adding cyclic transfers.

The first patch is a real bug fix which triggered in my case, the second
just fixes a typo, the third one is a preparation patch to ease the
review of the fourth one which actually adds cyclic transfers support.

Thanks,
Miquèl

Miquel Raynal (4):
  dmaengine: xilinx: xdma: Fix interrupt vector setting
  dmaengine: xilinx: xdma: Fix typo
  dmaengine: xilinx: xdma: Prepare the introduction of cyclic transfers
  dmaengine: xilinx: xdma: Support cyclic transfers

 drivers/dma/xilinx/xdma-regs.h |   2 +
 drivers/dma/xilinx/xdma.c      | 190 +++++++++++++++++++++++++++++++--
 2 files changed, 183 insertions(+), 9 deletions(-)

-- 
2.34.1


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[PATCH 1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting

[Miquel Raynal]

A couple of hardware registers need to be set to reflect which
interrupts have been allocated to the device. Each register is 32-bit
wide and can receive four 8-bit values. If we provide any other interrupt
number than four, the irq_num variable will never be 0 within the while
check and the while block will loop forever.

There is an easy way to prevent this: just break the for loop
when we reach "irq_num == 0", which anyway means all interrupts have
been processed.

Cc: stable@vger.kernel.org
Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 93ee298d52b8..359123526dd0 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -668,6 +668,8 @@ static int xdma_set_vector_reg(struct xdma_device *xdev, u32 vec_tbl_start,
 			val |= irq_start << shift;
 			irq_start++;
 			irq_num--;
+			if (!irq_num)
+				break;
 		}
 
 		/* write IRQ register */
-- 
2.34.1

[PATCH 1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting

[Miquel Raynal]

A couple of hardware registers need to be set to reflect which
interrupts have been allocated to the device. Each register is 32-bit
wide and can receive four 8-bit values. If we provide any other interrupt
number than four, the irq_num variable will never be 0 within the while
check and the while block will loop forever.

There is an easy way to prevent this: just break the for loop
when we reach "irq_num == 0", which anyway means all interrupts have
been processed.

Cc: stable@vger.kernel.org
Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 93ee298d52b8..359123526dd0 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -668,6 +668,8 @@ static int xdma_set_vector_reg(struct xdma_device *xdev, u32 vec_tbl_start,
 			val |= irq_start << shift;
 			irq_start++;
 			irq_num--;
+			if (!irq_num)
+				break;
 		}
 
 		/* write IRQ register */
-- 
2.34.1


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Re: [PATCH 1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting

[Lizhi Hou]

On 7/31/23 03:14, Miquel Raynal wrote:
> A couple of hardware registers need to be set to reflect which
> interrupts have been allocated to the device. Each register is 32-bit
> wide and can receive four 8-bit values. If we provide any other interrupt
> number than four, the irq_num variable will never be 0 within the while
> check and the while block will loop forever.
>
> There is an easy way to prevent this: just break the for loop
> when we reach "irq_num == 0", which anyway means all interrupts have
> been processed.
>
> Cc: stable@vger.kernel.org
> Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>   drivers/dma/xilinx/xdma.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
> index 93ee298d52b8..359123526dd0 100644
> --- a/drivers/dma/xilinx/xdma.c
> +++ b/drivers/dma/xilinx/xdma.c
> @@ -668,6 +668,8 @@ static int xdma_set_vector_reg(struct xdma_device *xdev, u32 vec_tbl_start,
>   			val |= irq_start << shift;
>   			irq_start++;
>   			irq_num--;
> +			if (!irq_num)
> +				break;

Thanks for fixing this.

Acked-by: Lizhi Hou <lizhi.hou@amd.com>


Lizhi

>   		}
>   
>   		/* write IRQ register */

Re: [PATCH 1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting

[Lizhi Hou]

On 7/31/23 03:14, Miquel Raynal wrote:
> A couple of hardware registers need to be set to reflect which
> interrupts have been allocated to the device. Each register is 32-bit
> wide and can receive four 8-bit values. If we provide any other interrupt
> number than four, the irq_num variable will never be 0 within the while
> check and the while block will loop forever.
>
> There is an easy way to prevent this: just break the for loop
> when we reach "irq_num == 0", which anyway means all interrupts have
> been processed.
>
> Cc: stable@vger.kernel.org
> Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>   drivers/dma/xilinx/xdma.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
> index 93ee298d52b8..359123526dd0 100644
> --- a/drivers/dma/xilinx/xdma.c
> +++ b/drivers/dma/xilinx/xdma.c
> @@ -668,6 +668,8 @@ static int xdma_set_vector_reg(struct xdma_device *xdev, u32 vec_tbl_start,
>   			val |= irq_start << shift;
>   			irq_start++;
>   			irq_num--;
> +			if (!irq_num)
> +				break;

Thanks for fixing this.

Acked-by: Lizhi Hou <lizhi.hou@amd.com>


Lizhi

>   		}
>   
>   		/* write IRQ register */

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[PATCH 2/4] dmaengine: xilinx: xdma: Fix typo

[Miquel Raynal]

Probably a copy/paste error with the previous block, here we are
actually managing C2H IRQs.

Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 359123526dd0..5cdb19bd80a7 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -717,7 +717,7 @@ static int xdma_irq_init(struct xdma_device *xdev)
 		ret = request_irq(irq, xdma_channel_isr, 0,
 				  "xdma-c2h-channel", &xdev->c2h_chans[j]);
 		if (ret) {
-			xdma_err(xdev, "H2C channel%d request irq%d failed: %d",
+			xdma_err(xdev, "C2H channel%d request irq%d failed: %d",
 				 j, irq, ret);
 			goto failed_init_c2h;
 		}
-- 
2.34.1

[PATCH 2/4] dmaengine: xilinx: xdma: Fix typo

[Miquel Raynal]

Probably a copy/paste error with the previous block, here we are
actually managing C2H IRQs.

Fixes: 17ce252266c7 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 359123526dd0..5cdb19bd80a7 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -717,7 +717,7 @@ static int xdma_irq_init(struct xdma_device *xdev)
 		ret = request_irq(irq, xdma_channel_isr, 0,
 				  "xdma-c2h-channel", &xdev->c2h_chans[j]);
 		if (ret) {
-			xdma_err(xdev, "H2C channel%d request irq%d failed: %d",
+			xdma_err(xdev, "C2H channel%d request irq%d failed: %d",
 				 j, irq, ret);
 			goto failed_init_c2h;
 		}
-- 
2.34.1


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[PATCH 3/4] dmaengine: xilinx: xdma: Prepare the introduction of cyclic transfers

[Miquel Raynal]

In order to reduce and clarify the diff when introducing cyclic
transfers support, let's first prepare the driver a bit. There is no
functional change.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 5cdb19bd80a7..40983d9355c4 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -137,10 +137,10 @@ static inline void *xdma_blk_last_desc(struct xdma_desc_block *block)
 }
 
 /**
- * xdma_link_desc_blocks - Link descriptor blocks for DMA transfer
+ * xdma_link_sg_desc_blocks - Link SG descriptor blocks for DMA transfer
  * @sw_desc: Tx descriptor pointer
  */
-static void xdma_link_desc_blocks(struct xdma_desc *sw_desc)
+static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
 {
 	struct xdma_desc_block *block;
 	u32 last_blk_desc, desc_control;
@@ -239,6 +239,7 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 	struct xdma_hw_desc *desc;
 	dma_addr_t dma_addr;
 	u32 dblk_num;
+	u32 control;
 	void *addr;
 	int i, j;
 
@@ -254,6 +255,8 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 	if (!sw_desc->desc_blocks)
 		goto failed;
 
+	control = XDMA_DESC_CONTROL(1, 0);
+
 	sw_desc->dblk_num = dblk_num;
 	for (i = 0; i < sw_desc->dblk_num; i++) {
 		addr = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT, &dma_addr);
@@ -263,10 +266,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 		sw_desc->desc_blocks[i].virt_addr = addr;
 		sw_desc->desc_blocks[i].dma_addr = dma_addr;
 		for (j = 0, desc = addr; j < XDMA_DESC_ADJACENT; j++)
-			desc[j].control = cpu_to_le32(XDMA_DESC_CONTROL(1, 0));
+			desc[j].control = cpu_to_le32(control);
 	}
 
-	xdma_link_desc_blocks(sw_desc);
+	xdma_link_sg_desc_blocks(sw_desc);
 
 	return sw_desc;
 
@@ -577,6 +580,12 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
 	return 0;
 }
 
+static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
+				      struct dma_tx_state *state)
+{
+	return dma_cookie_status(chan, cookie, state);
+}
+
 /**
  * xdma_channel_isr - XDMA channel interrupt handler
  * @irq: IRQ number
@@ -925,7 +934,7 @@ static int xdma_probe(struct platform_device *pdev)
 	xdev->dma_dev.dev = &pdev->dev;
 	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
 	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
-	xdev->dma_dev.device_tx_status = dma_cookie_status;
+	xdev->dma_dev.device_tx_status = xdma_tx_status;
 	xdev->dma_dev.device_prep_slave_sg = xdma_prep_device_sg;
 	xdev->dma_dev.device_config = xdma_device_config;
 	xdev->dma_dev.device_issue_pending = xdma_issue_pending;
-- 
2.34.1

[PATCH 3/4] dmaengine: xilinx: xdma: Prepare the introduction of cyclic transfers

[Miquel Raynal]

In order to reduce and clarify the diff when introducing cyclic
transfers support, let's first prepare the driver a bit. There is no
functional change.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 5cdb19bd80a7..40983d9355c4 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -137,10 +137,10 @@ static inline void *xdma_blk_last_desc(struct xdma_desc_block *block)
 }
 
 /**
- * xdma_link_desc_blocks - Link descriptor blocks for DMA transfer
+ * xdma_link_sg_desc_blocks - Link SG descriptor blocks for DMA transfer
  * @sw_desc: Tx descriptor pointer
  */
-static void xdma_link_desc_blocks(struct xdma_desc *sw_desc)
+static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
 {
 	struct xdma_desc_block *block;
 	u32 last_blk_desc, desc_control;
@@ -239,6 +239,7 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 	struct xdma_hw_desc *desc;
 	dma_addr_t dma_addr;
 	u32 dblk_num;
+	u32 control;
 	void *addr;
 	int i, j;
 
@@ -254,6 +255,8 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 	if (!sw_desc->desc_blocks)
 		goto failed;
 
+	control = XDMA_DESC_CONTROL(1, 0);
+
 	sw_desc->dblk_num = dblk_num;
 	for (i = 0; i < sw_desc->dblk_num; i++) {
 		addr = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT, &dma_addr);
@@ -263,10 +266,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 		sw_desc->desc_blocks[i].virt_addr = addr;
 		sw_desc->desc_blocks[i].dma_addr = dma_addr;
 		for (j = 0, desc = addr; j < XDMA_DESC_ADJACENT; j++)
-			desc[j].control = cpu_to_le32(XDMA_DESC_CONTROL(1, 0));
+			desc[j].control = cpu_to_le32(control);
 	}
 
-	xdma_link_desc_blocks(sw_desc);
+	xdma_link_sg_desc_blocks(sw_desc);
 
 	return sw_desc;
 
@@ -577,6 +580,12 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
 	return 0;
 }
 
+static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
+				      struct dma_tx_state *state)
+{
+	return dma_cookie_status(chan, cookie, state);
+}
+
 /**
  * xdma_channel_isr - XDMA channel interrupt handler
  * @irq: IRQ number
@@ -925,7 +934,7 @@ static int xdma_probe(struct platform_device *pdev)
 	xdev->dma_dev.dev = &pdev->dev;
 	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
 	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
-	xdev->dma_dev.device_tx_status = dma_cookie_status;
+	xdev->dma_dev.device_tx_status = xdma_tx_status;
 	xdev->dma_dev.device_prep_slave_sg = xdma_prep_device_sg;
 	xdev->dma_dev.device_config = xdma_device_config;
 	xdev->dma_dev.device_issue_pending = xdma_issue_pending;
-- 
2.34.1


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[PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Miquel Raynal]

In order to use this dmaengine with sound devices, let's add cyclic
transfers support. Most of the code is reused from the existing
scatter-gather implementation, only the final linking between
descriptors, the control fields (to trigger interrupts more often) and
the interrupt handling are really different.

This controller supports up to 32 adjacent descriptors, we assume this
is way more than enough for the purpose of cyclic transfers and limit to
32 the number of cycled descriptors. This way, we simplify a lot the
overall handling of the descriptors.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma-regs.h |   2 +
 drivers/dma/xilinx/xdma.c      | 173 +++++++++++++++++++++++++++++++--
 2 files changed, 169 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
index dd98b4526b90..e641a5083e14 100644
--- a/drivers/dma/xilinx/xdma-regs.h
+++ b/drivers/dma/xilinx/xdma-regs.h
@@ -44,6 +44,8 @@
 	 FIELD_PREP(XDMA_DESC_FLAGS_BITS, (flag)))
 #define XDMA_DESC_CONTROL_LAST						\
 	XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
+#define XDMA_DESC_CONTROL_CYCLIC					\
+	XDMA_DESC_CONTROL(1, XDMA_DESC_COMPLETED)
 
 /*
  * Descriptor for a single contiguous memory block transfer.
diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 40983d9355c4..be3a212be30c 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -83,6 +83,9 @@ struct xdma_chan {
  * @dblk_num: Number of hardware descriptor blocks
  * @desc_num: Number of hardware descriptors
  * @completed_desc_num: Completed hardware descriptors
+ * @cyclic: Cyclic transfer vs. scatter-gather
+ * @periods: Number of periods in the cyclic transfer
+ * @period_size: Size of a period in bytes in cyclic transfers
  */
 struct xdma_desc {
 	struct virt_dma_desc		vdesc;
@@ -93,6 +96,9 @@ struct xdma_desc {
 	u32				dblk_num;
 	u32				desc_num;
 	u32				completed_desc_num;
+	bool				cyclic;
+	u32				periods;
+	u32				period_size;
 };
 
 #define XDMA_DEV_STATUS_REG_DMA		BIT(0)
@@ -174,6 +180,25 @@ static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
 	desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
 }
 
+/**
+ * xdma_link_cyclic_desc_blocks - Link cyclic descriptor blocks for DMA transfer
+ * @sw_desc: Tx descriptor pointer
+ */
+static void xdma_link_cyclic_desc_blocks(struct xdma_desc *sw_desc)
+{
+	struct xdma_desc_block *block;
+	struct xdma_hw_desc *desc;
+	int i;
+
+	block = sw_desc->desc_blocks;
+	for (i = 0; i < sw_desc->desc_num - 1; i++) {
+		desc = block->virt_addr + i * XDMA_DESC_SIZE;
+		desc->next_desc = cpu_to_le64(block->dma_addr + ((i + 1) * XDMA_DESC_SIZE));
+	}
+	desc = block->virt_addr + i * XDMA_DESC_SIZE;
+	desc->next_desc = cpu_to_le64(block->dma_addr);
+}
+
 static inline struct xdma_chan *to_xdma_chan(struct dma_chan *chan)
 {
 	return container_of(chan, struct xdma_chan, vchan.chan);
@@ -233,7 +258,7 @@ static void xdma_free_desc(struct virt_dma_desc *vdesc)
  * @desc_num: Number of hardware descriptors
  */
 static struct xdma_desc *
-xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
+xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num, bool cyclic)
 {
 	struct xdma_desc *sw_desc;
 	struct xdma_hw_desc *desc;
@@ -249,13 +274,17 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 
 	sw_desc->chan = chan;
 	sw_desc->desc_num = desc_num;
+	sw_desc->cyclic = cyclic;
 	dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
 	sw_desc->desc_blocks = kcalloc(dblk_num, sizeof(*sw_desc->desc_blocks),
 				       GFP_NOWAIT);
 	if (!sw_desc->desc_blocks)
 		goto failed;
 
-	control = XDMA_DESC_CONTROL(1, 0);
+	if (cyclic)
+		control = XDMA_DESC_CONTROL_CYCLIC;
+	else
+		control = XDMA_DESC_CONTROL(1, 0);
 
 	sw_desc->dblk_num = dblk_num;
 	for (i = 0; i < sw_desc->dblk_num; i++) {
@@ -269,7 +298,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 			desc[j].control = cpu_to_le32(control);
 	}
 
-	xdma_link_sg_desc_blocks(sw_desc);
+	if (cyclic)
+		xdma_link_cyclic_desc_blocks(sw_desc);
+	else
+		xdma_link_sg_desc_blocks(sw_desc);
 
 	return sw_desc;
 
@@ -469,7 +501,7 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	for_each_sg(sgl, sg, sg_len, i)
 		desc_num += DIV_ROUND_UP(sg_dma_len(sg), XDMA_DESC_BLEN_MAX);
 
-	sw_desc = xdma_alloc_desc(xdma_chan, desc_num);
+	sw_desc = xdma_alloc_desc(xdma_chan, desc_num, false);
 	if (!sw_desc)
 		return NULL;
 	sw_desc->dir = dir;
@@ -524,6 +556,89 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	return NULL;
 }
 
+/**
+ * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
+ * @chan: DMA channel pointer
+ * @address: Device DMA address to access
+ * @size: Total length to transfer
+ * @period_size: Period size to use for each transfer
+ * @dir: Transfer direction
+ * @flags: Transfer ack flags
+ */
+static struct dma_async_tx_descriptor *
+xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
+		     size_t size, size_t period_size,
+		     enum dma_transfer_direction dir,
+		     unsigned long flags)
+{
+	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
+	struct xdma_device *xdev = xdma_chan->xdev_hdl;
+	unsigned int periods = size / period_size;
+	struct dma_async_tx_descriptor *tx_desc;
+	u64 addr, dev_addr, *src, *dst;
+	struct xdma_desc_block *dblk;
+	struct xdma_hw_desc *desc;
+	struct xdma_desc *sw_desc;
+	unsigned int i;
+
+	/*
+	 * Simplify the whole logic by preventing an abnormally high number of
+	 * periods and periods size.
+	 */
+	if (period_size > XDMA_DESC_BLEN_MAX) {
+		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
+		return NULL;
+	}
+
+	if (periods > XDMA_DESC_ADJACENT) {
+		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
+		return NULL;
+	}
+
+	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
+	if (!sw_desc)
+		return NULL;
+
+	sw_desc->periods = periods;
+	sw_desc->period_size = period_size;
+	sw_desc->dir = dir;
+
+	if (dir == DMA_MEM_TO_DEV) {
+		dev_addr = xdma_chan->cfg.dst_addr;
+		src = &addr;
+		dst = &dev_addr;
+	} else {
+		dev_addr = xdma_chan->cfg.src_addr;
+		src = &dev_addr;
+		dst = &addr;
+	}
+
+	dblk = sw_desc->desc_blocks;
+	desc = dblk->virt_addr;
+	for (i = 0; i < periods; i++) {
+		addr = address;
+
+		/* fill hardware descriptor */
+		desc->bytes = cpu_to_le32(period_size);
+		desc->src_addr = cpu_to_le64(*src);
+		desc->dst_addr = cpu_to_le64(*dst);
+
+		desc++;
+		address += period_size;
+	}
+
+	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
+	if (!tx_desc)
+		goto failed;
+
+	return tx_desc;
+
+failed:
+	xdma_free_desc(&sw_desc->vdesc);
+
+	return NULL;
+}
+
 /**
  * xdma_device_config - Configure the DMA channel
  * @chan: DMA channel
@@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
 static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
 				      struct dma_tx_state *state)
 {
-	return dma_cookie_status(chan, cookie, state);
+	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
+	struct virt_dma_desc *vd;
+	struct xdma_desc *desc;
+	enum dma_status ret;
+	unsigned long flags;
+	unsigned int period_idx;
+	u32 residue = 0;
+
+	ret = dma_cookie_status(chan, cookie, state);
+	if (ret == DMA_COMPLETE || !state)
+		return ret;
+
+	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
+
+	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
+	if (vd)
+		desc = to_xdma_desc(vd);
+	if (!desc || !desc->cyclic) {
+		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
+		return ret;
+	}
+
+	period_idx = desc->completed_desc_num % desc->periods;
+	residue = (desc->periods - period_idx) * desc->period_size;
+
+	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
+
+	dma_set_residue(state, residue);
+
+	return ret;
 }
 
 /**
@@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 	struct virt_dma_desc *vd;
 	struct xdma_desc *desc;
 	int ret;
+	u32 st;
 
 	spin_lock(&xchan->vchan.lock);
 
@@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 		goto out;
 
 	desc->completed_desc_num += complete_desc_num;
+
+	if (desc->cyclic) {
+		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
+				  &st);
+		if (ret)
+			goto out;
+
+		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);
+
+		vchan_cyclic_callback(vd);
+		goto out;
+	}
+
 	/*
 	 * if all data blocks are transferred, remove and complete the request
 	 */
@@ -630,7 +788,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 	    complete_desc_num != XDMA_DESC_BLOCK_NUM * XDMA_DESC_ADJACENT)
 		goto out;
 
-	/* transfer the rest of data */
+	/* transfer the rest of data (SG only) */
 	xdma_xfer_start(xchan);
 
 out:
@@ -930,8 +1088,10 @@ static int xdma_probe(struct platform_device *pdev)
 
 	dma_cap_set(DMA_SLAVE, xdev->dma_dev.cap_mask);
 	dma_cap_set(DMA_PRIVATE, xdev->dma_dev.cap_mask);
+	dma_cap_set(DMA_CYCLIC, xdev->dma_dev.cap_mask);
 
 	xdev->dma_dev.dev = &pdev->dev;
+	xdev->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
 	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
 	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
 	xdev->dma_dev.device_tx_status = xdma_tx_status;
@@ -941,6 +1101,7 @@ static int xdma_probe(struct platform_device *pdev)
 	xdev->dma_dev.filter.map = pdata->device_map;
 	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
 	xdev->dma_dev.filter.fn = xdma_filter_fn;
+	xdev->dma_dev.device_prep_dma_cyclic = xdma_prep_dma_cyclic;
 
 	ret = dma_async_device_register(&xdev->dma_dev);
 	if (ret) {
-- 
2.34.1

[PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Miquel Raynal]

In order to use this dmaengine with sound devices, let's add cyclic
transfers support. Most of the code is reused from the existing
scatter-gather implementation, only the final linking between
descriptors, the control fields (to trigger interrupts more often) and
the interrupt handling are really different.

This controller supports up to 32 adjacent descriptors, we assume this
is way more than enough for the purpose of cyclic transfers and limit to
32 the number of cycled descriptors. This way, we simplify a lot the
overall handling of the descriptors.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/dma/xilinx/xdma-regs.h |   2 +
 drivers/dma/xilinx/xdma.c      | 173 +++++++++++++++++++++++++++++++--
 2 files changed, 169 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
index dd98b4526b90..e641a5083e14 100644
--- a/drivers/dma/xilinx/xdma-regs.h
+++ b/drivers/dma/xilinx/xdma-regs.h
@@ -44,6 +44,8 @@
 	 FIELD_PREP(XDMA_DESC_FLAGS_BITS, (flag)))
 #define XDMA_DESC_CONTROL_LAST						\
 	XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
+#define XDMA_DESC_CONTROL_CYCLIC					\
+	XDMA_DESC_CONTROL(1, XDMA_DESC_COMPLETED)
 
 /*
  * Descriptor for a single contiguous memory block transfer.
diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 40983d9355c4..be3a212be30c 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -83,6 +83,9 @@ struct xdma_chan {
  * @dblk_num: Number of hardware descriptor blocks
  * @desc_num: Number of hardware descriptors
  * @completed_desc_num: Completed hardware descriptors
+ * @cyclic: Cyclic transfer vs. scatter-gather
+ * @periods: Number of periods in the cyclic transfer
+ * @period_size: Size of a period in bytes in cyclic transfers
  */
 struct xdma_desc {
 	struct virt_dma_desc		vdesc;
@@ -93,6 +96,9 @@ struct xdma_desc {
 	u32				dblk_num;
 	u32				desc_num;
 	u32				completed_desc_num;
+	bool				cyclic;
+	u32				periods;
+	u32				period_size;
 };
 
 #define XDMA_DEV_STATUS_REG_DMA		BIT(0)
@@ -174,6 +180,25 @@ static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
 	desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
 }
 
+/**
+ * xdma_link_cyclic_desc_blocks - Link cyclic descriptor blocks for DMA transfer
+ * @sw_desc: Tx descriptor pointer
+ */
+static void xdma_link_cyclic_desc_blocks(struct xdma_desc *sw_desc)
+{
+	struct xdma_desc_block *block;
+	struct xdma_hw_desc *desc;
+	int i;
+
+	block = sw_desc->desc_blocks;
+	for (i = 0; i < sw_desc->desc_num - 1; i++) {
+		desc = block->virt_addr + i * XDMA_DESC_SIZE;
+		desc->next_desc = cpu_to_le64(block->dma_addr + ((i + 1) * XDMA_DESC_SIZE));
+	}
+	desc = block->virt_addr + i * XDMA_DESC_SIZE;
+	desc->next_desc = cpu_to_le64(block->dma_addr);
+}
+
 static inline struct xdma_chan *to_xdma_chan(struct dma_chan *chan)
 {
 	return container_of(chan, struct xdma_chan, vchan.chan);
@@ -233,7 +258,7 @@ static void xdma_free_desc(struct virt_dma_desc *vdesc)
  * @desc_num: Number of hardware descriptors
  */
 static struct xdma_desc *
-xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
+xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num, bool cyclic)
 {
 	struct xdma_desc *sw_desc;
 	struct xdma_hw_desc *desc;
@@ -249,13 +274,17 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 
 	sw_desc->chan = chan;
 	sw_desc->desc_num = desc_num;
+	sw_desc->cyclic = cyclic;
 	dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
 	sw_desc->desc_blocks = kcalloc(dblk_num, sizeof(*sw_desc->desc_blocks),
 				       GFP_NOWAIT);
 	if (!sw_desc->desc_blocks)
 		goto failed;
 
-	control = XDMA_DESC_CONTROL(1, 0);
+	if (cyclic)
+		control = XDMA_DESC_CONTROL_CYCLIC;
+	else
+		control = XDMA_DESC_CONTROL(1, 0);
 
 	sw_desc->dblk_num = dblk_num;
 	for (i = 0; i < sw_desc->dblk_num; i++) {
@@ -269,7 +298,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
 			desc[j].control = cpu_to_le32(control);
 	}
 
-	xdma_link_sg_desc_blocks(sw_desc);
+	if (cyclic)
+		xdma_link_cyclic_desc_blocks(sw_desc);
+	else
+		xdma_link_sg_desc_blocks(sw_desc);
 
 	return sw_desc;
 
@@ -469,7 +501,7 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	for_each_sg(sgl, sg, sg_len, i)
 		desc_num += DIV_ROUND_UP(sg_dma_len(sg), XDMA_DESC_BLEN_MAX);
 
-	sw_desc = xdma_alloc_desc(xdma_chan, desc_num);
+	sw_desc = xdma_alloc_desc(xdma_chan, desc_num, false);
 	if (!sw_desc)
 		return NULL;
 	sw_desc->dir = dir;
@@ -524,6 +556,89 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	return NULL;
 }
 
+/**
+ * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
+ * @chan: DMA channel pointer
+ * @address: Device DMA address to access
+ * @size: Total length to transfer
+ * @period_size: Period size to use for each transfer
+ * @dir: Transfer direction
+ * @flags: Transfer ack flags
+ */
+static struct dma_async_tx_descriptor *
+xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
+		     size_t size, size_t period_size,
+		     enum dma_transfer_direction dir,
+		     unsigned long flags)
+{
+	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
+	struct xdma_device *xdev = xdma_chan->xdev_hdl;
+	unsigned int periods = size / period_size;
+	struct dma_async_tx_descriptor *tx_desc;
+	u64 addr, dev_addr, *src, *dst;
+	struct xdma_desc_block *dblk;
+	struct xdma_hw_desc *desc;
+	struct xdma_desc *sw_desc;
+	unsigned int i;
+
+	/*
+	 * Simplify the whole logic by preventing an abnormally high number of
+	 * periods and periods size.
+	 */
+	if (period_size > XDMA_DESC_BLEN_MAX) {
+		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
+		return NULL;
+	}
+
+	if (periods > XDMA_DESC_ADJACENT) {
+		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
+		return NULL;
+	}
+
+	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
+	if (!sw_desc)
+		return NULL;
+
+	sw_desc->periods = periods;
+	sw_desc->period_size = period_size;
+	sw_desc->dir = dir;
+
+	if (dir == DMA_MEM_TO_DEV) {
+		dev_addr = xdma_chan->cfg.dst_addr;
+		src = &addr;
+		dst = &dev_addr;
+	} else {
+		dev_addr = xdma_chan->cfg.src_addr;
+		src = &dev_addr;
+		dst = &addr;
+	}
+
+	dblk = sw_desc->desc_blocks;
+	desc = dblk->virt_addr;
+	for (i = 0; i < periods; i++) {
+		addr = address;
+
+		/* fill hardware descriptor */
+		desc->bytes = cpu_to_le32(period_size);
+		desc->src_addr = cpu_to_le64(*src);
+		desc->dst_addr = cpu_to_le64(*dst);
+
+		desc++;
+		address += period_size;
+	}
+
+	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
+	if (!tx_desc)
+		goto failed;
+
+	return tx_desc;
+
+failed:
+	xdma_free_desc(&sw_desc->vdesc);
+
+	return NULL;
+}
+
 /**
  * xdma_device_config - Configure the DMA channel
  * @chan: DMA channel
@@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
 static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
 				      struct dma_tx_state *state)
 {
-	return dma_cookie_status(chan, cookie, state);
+	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
+	struct virt_dma_desc *vd;
+	struct xdma_desc *desc;
+	enum dma_status ret;
+	unsigned long flags;
+	unsigned int period_idx;
+	u32 residue = 0;
+
+	ret = dma_cookie_status(chan, cookie, state);
+	if (ret == DMA_COMPLETE || !state)
+		return ret;
+
+	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
+
+	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
+	if (vd)
+		desc = to_xdma_desc(vd);
+	if (!desc || !desc->cyclic) {
+		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
+		return ret;
+	}
+
+	period_idx = desc->completed_desc_num % desc->periods;
+	residue = (desc->periods - period_idx) * desc->period_size;
+
+	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
+
+	dma_set_residue(state, residue);
+
+	return ret;
 }
 
 /**
@@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 	struct virt_dma_desc *vd;
 	struct xdma_desc *desc;
 	int ret;
+	u32 st;
 
 	spin_lock(&xchan->vchan.lock);
 
@@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 		goto out;
 
 	desc->completed_desc_num += complete_desc_num;
+
+	if (desc->cyclic) {
+		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
+				  &st);
+		if (ret)
+			goto out;
+
+		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);
+
+		vchan_cyclic_callback(vd);
+		goto out;
+	}
+
 	/*
 	 * if all data blocks are transferred, remove and complete the request
 	 */
@@ -630,7 +788,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
 	    complete_desc_num != XDMA_DESC_BLOCK_NUM * XDMA_DESC_ADJACENT)
 		goto out;
 
-	/* transfer the rest of data */
+	/* transfer the rest of data (SG only) */
 	xdma_xfer_start(xchan);
 
 out:
@@ -930,8 +1088,10 @@ static int xdma_probe(struct platform_device *pdev)
 
 	dma_cap_set(DMA_SLAVE, xdev->dma_dev.cap_mask);
 	dma_cap_set(DMA_PRIVATE, xdev->dma_dev.cap_mask);
+	dma_cap_set(DMA_CYCLIC, xdev->dma_dev.cap_mask);
 
 	xdev->dma_dev.dev = &pdev->dev;
+	xdev->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
 	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
 	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
 	xdev->dma_dev.device_tx_status = xdma_tx_status;
@@ -941,6 +1101,7 @@ static int xdma_probe(struct platform_device *pdev)
 	xdev->dma_dev.filter.map = pdata->device_map;
 	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
 	xdev->dma_dev.filter.fn = xdma_filter_fn;
+	xdev->dma_dev.device_prep_dma_cyclic = xdma_prep_dma_cyclic;
 
 	ret = dma_async_device_register(&xdev->dma_dev);
 	if (ret) {
-- 
2.34.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[kernel test robot]

Hi Miquel,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.5-rc4 next-20230731]
[cannot apply to xilinx-xlnx/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Miquel-Raynal/dmaengine-xilinx-xdma-Fix-interrupt-vector-setting/20230731-181620
base:   linus/master
patch link:    https://lore.kernel.org/r/20230731101442.792514-5-miquel.raynal%40bootlin.com
patch subject: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers
config: powerpc-randconfig-r026-20230731 (https://download.01.org/0day-ci/archive/20230731/202307312225.9ewyJsVx-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230731/202307312225.9ewyJsVx-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307312225.9ewyJsVx-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/dma/xilinx/xdma.c:716:6: warning: variable 'desc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     716 |         if (vd)
         |             ^~
   drivers/dma/xilinx/xdma.c:718:7: note: uninitialized use occurs here
     718 |         if (!desc || !desc->cyclic) {
         |              ^~~~
   drivers/dma/xilinx/xdma.c:716:2: note: remove the 'if' if its condition is always true
     716 |         if (vd)
         |         ^~~~~~~
     717 |                 desc = to_xdma_desc(vd);
         | ~~~~~~~~~~~~~~~~
   drivers/dma/xilinx/xdma.c:703:24: note: initialize the variable 'desc' to silence this warning
     703 |         struct xdma_desc *desc;
         |                               ^
         |                                = NULL
   1 warning generated.


vim +716 drivers/dma/xilinx/xdma.c

   697	
   698	static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
   699					      struct dma_tx_state *state)
   700	{
   701		struct xdma_chan *xdma_chan = to_xdma_chan(chan);
   702		struct virt_dma_desc *vd;
   703		struct xdma_desc *desc;
   704		enum dma_status ret;
   705		unsigned long flags;
   706		unsigned int period_idx;
   707		u32 residue = 0;
   708	
   709		ret = dma_cookie_status(chan, cookie, state);
   710		if (ret == DMA_COMPLETE || !state)
   711			return ret;
   712	
   713		spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
   714	
   715		vd = vchan_find_desc(&xdma_chan->vchan, cookie);
 > 716		if (vd)
   717			desc = to_xdma_desc(vd);
   718		if (!desc || !desc->cyclic) {
   719			spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
   720			return ret;
   721		}
   722	
   723		period_idx = desc->completed_desc_num % desc->periods;
   724		residue = (desc->periods - period_idx) * desc->period_size;
   725	
   726		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
   727	
   728		dma_set_residue(state, residue);
   729	
   730		return ret;
   731	}
   732	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[kernel test robot]

Hi Miquel,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.5-rc4 next-20230731]
[cannot apply to xilinx-xlnx/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Miquel-Raynal/dmaengine-xilinx-xdma-Fix-interrupt-vector-setting/20230731-181620
base:   linus/master
patch link:    https://lore.kernel.org/r/20230731101442.792514-5-miquel.raynal%40bootlin.com
patch subject: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers
config: powerpc-randconfig-r026-20230731 (https://download.01.org/0day-ci/archive/20230731/202307312225.9ewyJsVx-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230731/202307312225.9ewyJsVx-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307312225.9ewyJsVx-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/dma/xilinx/xdma.c:716:6: warning: variable 'desc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     716 |         if (vd)
         |             ^~
   drivers/dma/xilinx/xdma.c:718:7: note: uninitialized use occurs here
     718 |         if (!desc || !desc->cyclic) {
         |              ^~~~
   drivers/dma/xilinx/xdma.c:716:2: note: remove the 'if' if its condition is always true
     716 |         if (vd)
         |         ^~~~~~~
     717 |                 desc = to_xdma_desc(vd);
         | ~~~~~~~~~~~~~~~~
   drivers/dma/xilinx/xdma.c:703:24: note: initialize the variable 'desc' to silence this warning
     703 |         struct xdma_desc *desc;
         |                               ^
         |                                = NULL
   1 warning generated.


vim +716 drivers/dma/xilinx/xdma.c

   697	
   698	static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
   699					      struct dma_tx_state *state)
   700	{
   701		struct xdma_chan *xdma_chan = to_xdma_chan(chan);
   702		struct virt_dma_desc *vd;
   703		struct xdma_desc *desc;
   704		enum dma_status ret;
   705		unsigned long flags;
   706		unsigned int period_idx;
   707		u32 residue = 0;
   708	
   709		ret = dma_cookie_status(chan, cookie, state);
   710		if (ret == DMA_COMPLETE || !state)
   711			return ret;
   712	
   713		spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
   714	
   715		vd = vchan_find_desc(&xdma_chan->vchan, cookie);
 > 716		if (vd)
   717			desc = to_xdma_desc(vd);
   718		if (!desc || !desc->cyclic) {
   719			spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
   720			return ret;
   721		}
   722	
   723		period_idx = desc->completed_desc_num % desc->periods;
   724		residue = (desc->periods - period_idx) * desc->period_size;
   725	
   726		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
   727	
   728		dma_set_residue(state, residue);
   729	
   730		return ret;
   731	}
   732	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

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linux-arm-kernel@lists.infradead.org
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Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Lizhi Hou]

On 7/31/23 03:14, Miquel Raynal wrote:
> In order to use this dmaengine with sound devices, let's add cyclic
> transfers support. Most of the code is reused from the existing
> scatter-gather implementation, only the final linking between
> descriptors, the control fields (to trigger interrupts more often) and
> the interrupt handling are really different.
>
> This controller supports up to 32 adjacent descriptors, we assume this
> is way more than enough for the purpose of cyclic transfers and limit to
> 32 the number of cycled descriptors. This way, we simplify a lot the
> overall handling of the descriptors.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>   drivers/dma/xilinx/xdma-regs.h |   2 +
>   drivers/dma/xilinx/xdma.c      | 173 +++++++++++++++++++++++++++++++--
>   2 files changed, 169 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
> index dd98b4526b90..e641a5083e14 100644
> --- a/drivers/dma/xilinx/xdma-regs.h
> +++ b/drivers/dma/xilinx/xdma-regs.h
> @@ -44,6 +44,8 @@
>   	 FIELD_PREP(XDMA_DESC_FLAGS_BITS, (flag)))
>   #define XDMA_DESC_CONTROL_LAST						\
>   	XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
> +#define XDMA_DESC_CONTROL_CYCLIC					\
> +	XDMA_DESC_CONTROL(1, XDMA_DESC_COMPLETED)
>   
>   /*
>    * Descriptor for a single contiguous memory block transfer.
> diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
> index 40983d9355c4..be3a212be30c 100644
> --- a/drivers/dma/xilinx/xdma.c
> +++ b/drivers/dma/xilinx/xdma.c
> @@ -83,6 +83,9 @@ struct xdma_chan {
>    * @dblk_num: Number of hardware descriptor blocks
>    * @desc_num: Number of hardware descriptors
>    * @completed_desc_num: Completed hardware descriptors
> + * @cyclic: Cyclic transfer vs. scatter-gather
> + * @periods: Number of periods in the cyclic transfer
> + * @period_size: Size of a period in bytes in cyclic transfers
>    */
>   struct xdma_desc {
>   	struct virt_dma_desc		vdesc;
> @@ -93,6 +96,9 @@ struct xdma_desc {
>   	u32				dblk_num;
>   	u32				desc_num;
>   	u32				completed_desc_num;
> +	bool				cyclic;
> +	u32				periods;
> +	u32				period_size;
>   };
>   
>   #define XDMA_DEV_STATUS_REG_DMA		BIT(0)
> @@ -174,6 +180,25 @@ static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
>   	desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
>   }
>   
> +/**
> + * xdma_link_cyclic_desc_blocks - Link cyclic descriptor blocks for DMA transfer
> + * @sw_desc: Tx descriptor pointer
> + */
> +static void xdma_link_cyclic_desc_blocks(struct xdma_desc *sw_desc)
> +{
> +	struct xdma_desc_block *block;
> +	struct xdma_hw_desc *desc;
> +	int i;
> +
> +	block = sw_desc->desc_blocks;
> +	for (i = 0; i < sw_desc->desc_num - 1; i++) {
> +		desc = block->virt_addr + i * XDMA_DESC_SIZE;
> +		desc->next_desc = cpu_to_le64(block->dma_addr + ((i + 1) * XDMA_DESC_SIZE));
> +	}
> +	desc = block->virt_addr + i * XDMA_DESC_SIZE;
> +	desc->next_desc = cpu_to_le64(block->dma_addr);
> +}
> +
>   static inline struct xdma_chan *to_xdma_chan(struct dma_chan *chan)
>   {
>   	return container_of(chan, struct xdma_chan, vchan.chan);
> @@ -233,7 +258,7 @@ static void xdma_free_desc(struct virt_dma_desc *vdesc)
>    * @desc_num: Number of hardware descriptors
>    */
>   static struct xdma_desc *
> -xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
> +xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num, bool cyclic)
>   {
>   	struct xdma_desc *sw_desc;
>   	struct xdma_hw_desc *desc;
> @@ -249,13 +274,17 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
>   
>   	sw_desc->chan = chan;
>   	sw_desc->desc_num = desc_num;
> +	sw_desc->cyclic = cyclic;
>   	dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
>   	sw_desc->desc_blocks = kcalloc(dblk_num, sizeof(*sw_desc->desc_blocks),
>   				       GFP_NOWAIT);
>   	if (!sw_desc->desc_blocks)
>   		goto failed;
>   
> -	control = XDMA_DESC_CONTROL(1, 0);
> +	if (cyclic)
> +		control = XDMA_DESC_CONTROL_CYCLIC;
> +	else
> +		control = XDMA_DESC_CONTROL(1, 0);
>   
>   	sw_desc->dblk_num = dblk_num;
>   	for (i = 0; i < sw_desc->dblk_num; i++) {
> @@ -269,7 +298,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
>   			desc[j].control = cpu_to_le32(control);
>   	}
>   
> -	xdma_link_sg_desc_blocks(sw_desc);
> +	if (cyclic)
> +		xdma_link_cyclic_desc_blocks(sw_desc);
> +	else
> +		xdma_link_sg_desc_blocks(sw_desc);
>   
>   	return sw_desc;
>   
> @@ -469,7 +501,7 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
>   	for_each_sg(sgl, sg, sg_len, i)
>   		desc_num += DIV_ROUND_UP(sg_dma_len(sg), XDMA_DESC_BLEN_MAX);
>   
> -	sw_desc = xdma_alloc_desc(xdma_chan, desc_num);
> +	sw_desc = xdma_alloc_desc(xdma_chan, desc_num, false);
>   	if (!sw_desc)
>   		return NULL;
>   	sw_desc->dir = dir;
> @@ -524,6 +556,89 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
>   	return NULL;
>   }
>   
> +/**
> + * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
> + * @chan: DMA channel pointer
> + * @address: Device DMA address to access
> + * @size: Total length to transfer
> + * @period_size: Period size to use for each transfer
> + * @dir: Transfer direction
> + * @flags: Transfer ack flags
> + */
> +static struct dma_async_tx_descriptor *
> +xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
> +		     size_t size, size_t period_size,
> +		     enum dma_transfer_direction dir,
> +		     unsigned long flags)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> +	unsigned int periods = size / period_size;
What if size is not multiple of period_size?
> +	struct dma_async_tx_descriptor *tx_desc;
> +	u64 addr, dev_addr, *src, *dst;
> +	struct xdma_desc_block *dblk;
> +	struct xdma_hw_desc *desc;
> +	struct xdma_desc *sw_desc;
> +	unsigned int i;
> +
> +	/*
> +	 * Simplify the whole logic by preventing an abnormally high number of
> +	 * periods and periods size.
> +	 */
> +	if (period_size > XDMA_DESC_BLEN_MAX) {
> +		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
> +		return NULL;
> +	}
> +
> +	if (periods > XDMA_DESC_ADJACENT) {
> +		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
> +		return NULL;
> +	}
> +
> +	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
> +	if (!sw_desc)
> +		return NULL;
> +
> +	sw_desc->periods = periods;
> +	sw_desc->period_size = period_size;
> +	sw_desc->dir = dir;
> +
> +	if (dir == DMA_MEM_TO_DEV) {
> +		dev_addr = xdma_chan->cfg.dst_addr;
> +		src = &addr;
> +		dst = &dev_addr;
> +	} else {
> +		dev_addr = xdma_chan->cfg.src_addr;
> +		src = &dev_addr;
> +		dst = &addr;
> +	}
> +
> +	dblk = sw_desc->desc_blocks;
> +	desc = dblk->virt_addr;
> +	for (i = 0; i < periods; i++) {
> +		addr = address;
> +
> +		/* fill hardware descriptor */
> +		desc->bytes = cpu_to_le32(period_size);
> +		desc->src_addr = cpu_to_le64(*src);
> +		desc->dst_addr = cpu_to_le64(*dst);
> +
> +		desc++;
> +		address += period_size;
> +	}
> +
> +	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
> +	if (!tx_desc)
> +		goto failed;
> +
> +	return tx_desc;
> +
> +failed:
> +	xdma_free_desc(&sw_desc->vdesc);
> +
> +	return NULL;
> +}
> +
>   /**
>    * xdma_device_config - Configure the DMA channel
>    * @chan: DMA channel
> @@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
>   static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>   				      struct dma_tx_state *state)
>   {
> -	return dma_cookie_status(chan, cookie, state);
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct virt_dma_desc *vd;
> +	struct xdma_desc *desc;
> +	enum dma_status ret;
> +	unsigned long flags;
> +	unsigned int period_idx;
> +	u32 residue = 0;
> +
> +	ret = dma_cookie_status(chan, cookie, state);
> +	if (ret == DMA_COMPLETE || !state)
probably do not need to check state. Or at least check before calling 
dma_cookie_status.
> +		return ret;
> +
> +	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
> +
> +	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
> +	if (vd)
> +		desc = to_xdma_desc(vd);
> +	if (!desc || !desc->cyclic) {
desc is un-initialized if vd is NULL.
> +		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> +		return ret;
> +	}
> +
> +	period_idx = desc->completed_desc_num % desc->periods;
> +	residue = (desc->periods - period_idx) * desc->period_size;
> +
> +	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> +
> +	dma_set_residue(state, residue);
> +
> +	return ret;
>   }
>   
>   /**
> @@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   	struct virt_dma_desc *vd;
>   	struct xdma_desc *desc;
>   	int ret;
> +	u32 st;
>   
>   	spin_lock(&xchan->vchan.lock);
>   
> @@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   		goto out;
>   
>   	desc->completed_desc_num += complete_desc_num;
> +
> +	if (desc->cyclic) {
> +		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
> +				  &st);
> +		if (ret)
> +			goto out;
> +
> +		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);

What does reading/writing channel status register do here?


Thanks,

Lizhi

> +
> +		vchan_cyclic_callback(vd);
> +		goto out;
> +	}
> +
>   	/*
>   	 * if all data blocks are transferred, remove and complete the request
>   	 */
> @@ -630,7 +788,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   	    complete_desc_num != XDMA_DESC_BLOCK_NUM * XDMA_DESC_ADJACENT)
>   		goto out;
>   
> -	/* transfer the rest of data */
> +	/* transfer the rest of data (SG only) */
>   	xdma_xfer_start(xchan);
>   
>   out:
> @@ -930,8 +1088,10 @@ static int xdma_probe(struct platform_device *pdev)
>   
>   	dma_cap_set(DMA_SLAVE, xdev->dma_dev.cap_mask);
>   	dma_cap_set(DMA_PRIVATE, xdev->dma_dev.cap_mask);
> +	dma_cap_set(DMA_CYCLIC, xdev->dma_dev.cap_mask);
>   
>   	xdev->dma_dev.dev = &pdev->dev;
> +	xdev->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
>   	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
>   	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
>   	xdev->dma_dev.device_tx_status = xdma_tx_status;
> @@ -941,6 +1101,7 @@ static int xdma_probe(struct platform_device *pdev)
>   	xdev->dma_dev.filter.map = pdata->device_map;
>   	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
>   	xdev->dma_dev.filter.fn = xdma_filter_fn;
> +	xdev->dma_dev.device_prep_dma_cyclic = xdma_prep_dma_cyclic;
>   
>   	ret = dma_async_device_register(&xdev->dma_dev);
>   	if (ret) {

Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Lizhi Hou]

On 7/31/23 03:14, Miquel Raynal wrote:
> In order to use this dmaengine with sound devices, let's add cyclic
> transfers support. Most of the code is reused from the existing
> scatter-gather implementation, only the final linking between
> descriptors, the control fields (to trigger interrupts more often) and
> the interrupt handling are really different.
>
> This controller supports up to 32 adjacent descriptors, we assume this
> is way more than enough for the purpose of cyclic transfers and limit to
> 32 the number of cycled descriptors. This way, we simplify a lot the
> overall handling of the descriptors.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>   drivers/dma/xilinx/xdma-regs.h |   2 +
>   drivers/dma/xilinx/xdma.c      | 173 +++++++++++++++++++++++++++++++--
>   2 files changed, 169 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
> index dd98b4526b90..e641a5083e14 100644
> --- a/drivers/dma/xilinx/xdma-regs.h
> +++ b/drivers/dma/xilinx/xdma-regs.h
> @@ -44,6 +44,8 @@
>   	 FIELD_PREP(XDMA_DESC_FLAGS_BITS, (flag)))
>   #define XDMA_DESC_CONTROL_LAST						\
>   	XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
> +#define XDMA_DESC_CONTROL_CYCLIC					\
> +	XDMA_DESC_CONTROL(1, XDMA_DESC_COMPLETED)
>   
>   /*
>    * Descriptor for a single contiguous memory block transfer.
> diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
> index 40983d9355c4..be3a212be30c 100644
> --- a/drivers/dma/xilinx/xdma.c
> +++ b/drivers/dma/xilinx/xdma.c
> @@ -83,6 +83,9 @@ struct xdma_chan {
>    * @dblk_num: Number of hardware descriptor blocks
>    * @desc_num: Number of hardware descriptors
>    * @completed_desc_num: Completed hardware descriptors
> + * @cyclic: Cyclic transfer vs. scatter-gather
> + * @periods: Number of periods in the cyclic transfer
> + * @period_size: Size of a period in bytes in cyclic transfers
>    */
>   struct xdma_desc {
>   	struct virt_dma_desc		vdesc;
> @@ -93,6 +96,9 @@ struct xdma_desc {
>   	u32				dblk_num;
>   	u32				desc_num;
>   	u32				completed_desc_num;
> +	bool				cyclic;
> +	u32				periods;
> +	u32				period_size;
>   };
>   
>   #define XDMA_DEV_STATUS_REG_DMA		BIT(0)
> @@ -174,6 +180,25 @@ static void xdma_link_sg_desc_blocks(struct xdma_desc *sw_desc)
>   	desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
>   }
>   
> +/**
> + * xdma_link_cyclic_desc_blocks - Link cyclic descriptor blocks for DMA transfer
> + * @sw_desc: Tx descriptor pointer
> + */
> +static void xdma_link_cyclic_desc_blocks(struct xdma_desc *sw_desc)
> +{
> +	struct xdma_desc_block *block;
> +	struct xdma_hw_desc *desc;
> +	int i;
> +
> +	block = sw_desc->desc_blocks;
> +	for (i = 0; i < sw_desc->desc_num - 1; i++) {
> +		desc = block->virt_addr + i * XDMA_DESC_SIZE;
> +		desc->next_desc = cpu_to_le64(block->dma_addr + ((i + 1) * XDMA_DESC_SIZE));
> +	}
> +	desc = block->virt_addr + i * XDMA_DESC_SIZE;
> +	desc->next_desc = cpu_to_le64(block->dma_addr);
> +}
> +
>   static inline struct xdma_chan *to_xdma_chan(struct dma_chan *chan)
>   {
>   	return container_of(chan, struct xdma_chan, vchan.chan);
> @@ -233,7 +258,7 @@ static void xdma_free_desc(struct virt_dma_desc *vdesc)
>    * @desc_num: Number of hardware descriptors
>    */
>   static struct xdma_desc *
> -xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
> +xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num, bool cyclic)
>   {
>   	struct xdma_desc *sw_desc;
>   	struct xdma_hw_desc *desc;
> @@ -249,13 +274,17 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
>   
>   	sw_desc->chan = chan;
>   	sw_desc->desc_num = desc_num;
> +	sw_desc->cyclic = cyclic;
>   	dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
>   	sw_desc->desc_blocks = kcalloc(dblk_num, sizeof(*sw_desc->desc_blocks),
>   				       GFP_NOWAIT);
>   	if (!sw_desc->desc_blocks)
>   		goto failed;
>   
> -	control = XDMA_DESC_CONTROL(1, 0);
> +	if (cyclic)
> +		control = XDMA_DESC_CONTROL_CYCLIC;
> +	else
> +		control = XDMA_DESC_CONTROL(1, 0);
>   
>   	sw_desc->dblk_num = dblk_num;
>   	for (i = 0; i < sw_desc->dblk_num; i++) {
> @@ -269,7 +298,10 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
>   			desc[j].control = cpu_to_le32(control);
>   	}
>   
> -	xdma_link_sg_desc_blocks(sw_desc);
> +	if (cyclic)
> +		xdma_link_cyclic_desc_blocks(sw_desc);
> +	else
> +		xdma_link_sg_desc_blocks(sw_desc);
>   
>   	return sw_desc;
>   
> @@ -469,7 +501,7 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
>   	for_each_sg(sgl, sg, sg_len, i)
>   		desc_num += DIV_ROUND_UP(sg_dma_len(sg), XDMA_DESC_BLEN_MAX);
>   
> -	sw_desc = xdma_alloc_desc(xdma_chan, desc_num);
> +	sw_desc = xdma_alloc_desc(xdma_chan, desc_num, false);
>   	if (!sw_desc)
>   		return NULL;
>   	sw_desc->dir = dir;
> @@ -524,6 +556,89 @@ xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
>   	return NULL;
>   }
>   
> +/**
> + * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
> + * @chan: DMA channel pointer
> + * @address: Device DMA address to access
> + * @size: Total length to transfer
> + * @period_size: Period size to use for each transfer
> + * @dir: Transfer direction
> + * @flags: Transfer ack flags
> + */
> +static struct dma_async_tx_descriptor *
> +xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
> +		     size_t size, size_t period_size,
> +		     enum dma_transfer_direction dir,
> +		     unsigned long flags)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> +	unsigned int periods = size / period_size;
What if size is not multiple of period_size?
> +	struct dma_async_tx_descriptor *tx_desc;
> +	u64 addr, dev_addr, *src, *dst;
> +	struct xdma_desc_block *dblk;
> +	struct xdma_hw_desc *desc;
> +	struct xdma_desc *sw_desc;
> +	unsigned int i;
> +
> +	/*
> +	 * Simplify the whole logic by preventing an abnormally high number of
> +	 * periods and periods size.
> +	 */
> +	if (period_size > XDMA_DESC_BLEN_MAX) {
> +		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
> +		return NULL;
> +	}
> +
> +	if (periods > XDMA_DESC_ADJACENT) {
> +		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
> +		return NULL;
> +	}
> +
> +	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
> +	if (!sw_desc)
> +		return NULL;
> +
> +	sw_desc->periods = periods;
> +	sw_desc->period_size = period_size;
> +	sw_desc->dir = dir;
> +
> +	if (dir == DMA_MEM_TO_DEV) {
> +		dev_addr = xdma_chan->cfg.dst_addr;
> +		src = &addr;
> +		dst = &dev_addr;
> +	} else {
> +		dev_addr = xdma_chan->cfg.src_addr;
> +		src = &dev_addr;
> +		dst = &addr;
> +	}
> +
> +	dblk = sw_desc->desc_blocks;
> +	desc = dblk->virt_addr;
> +	for (i = 0; i < periods; i++) {
> +		addr = address;
> +
> +		/* fill hardware descriptor */
> +		desc->bytes = cpu_to_le32(period_size);
> +		desc->src_addr = cpu_to_le64(*src);
> +		desc->dst_addr = cpu_to_le64(*dst);
> +
> +		desc++;
> +		address += period_size;
> +	}
> +
> +	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
> +	if (!tx_desc)
> +		goto failed;
> +
> +	return tx_desc;
> +
> +failed:
> +	xdma_free_desc(&sw_desc->vdesc);
> +
> +	return NULL;
> +}
> +
>   /**
>    * xdma_device_config - Configure the DMA channel
>    * @chan: DMA channel
> @@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
>   static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>   				      struct dma_tx_state *state)
>   {
> -	return dma_cookie_status(chan, cookie, state);
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct virt_dma_desc *vd;
> +	struct xdma_desc *desc;
> +	enum dma_status ret;
> +	unsigned long flags;
> +	unsigned int period_idx;
> +	u32 residue = 0;
> +
> +	ret = dma_cookie_status(chan, cookie, state);
> +	if (ret == DMA_COMPLETE || !state)
probably do not need to check state. Or at least check before calling 
dma_cookie_status.
> +		return ret;
> +
> +	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
> +
> +	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
> +	if (vd)
> +		desc = to_xdma_desc(vd);
> +	if (!desc || !desc->cyclic) {
desc is un-initialized if vd is NULL.
> +		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> +		return ret;
> +	}
> +
> +	period_idx = desc->completed_desc_num % desc->periods;
> +	residue = (desc->periods - period_idx) * desc->period_size;
> +
> +	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> +
> +	dma_set_residue(state, residue);
> +
> +	return ret;
>   }
>   
>   /**
> @@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   	struct virt_dma_desc *vd;
>   	struct xdma_desc *desc;
>   	int ret;
> +	u32 st;
>   
>   	spin_lock(&xchan->vchan.lock);
>   
> @@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   		goto out;
>   
>   	desc->completed_desc_num += complete_desc_num;
> +
> +	if (desc->cyclic) {
> +		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
> +				  &st);
> +		if (ret)
> +			goto out;
> +
> +		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);

What does reading/writing channel status register do here?


Thanks,

Lizhi

> +
> +		vchan_cyclic_callback(vd);
> +		goto out;
> +	}
> +
>   	/*
>   	 * if all data blocks are transferred, remove and complete the request
>   	 */
> @@ -630,7 +788,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
>   	    complete_desc_num != XDMA_DESC_BLOCK_NUM * XDMA_DESC_ADJACENT)
>   		goto out;
>   
> -	/* transfer the rest of data */
> +	/* transfer the rest of data (SG only) */
>   	xdma_xfer_start(xchan);
>   
>   out:
> @@ -930,8 +1088,10 @@ static int xdma_probe(struct platform_device *pdev)
>   
>   	dma_cap_set(DMA_SLAVE, xdev->dma_dev.cap_mask);
>   	dma_cap_set(DMA_PRIVATE, xdev->dma_dev.cap_mask);
> +	dma_cap_set(DMA_CYCLIC, xdev->dma_dev.cap_mask);
>   
>   	xdev->dma_dev.dev = &pdev->dev;
> +	xdev->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
>   	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
>   	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
>   	xdev->dma_dev.device_tx_status = xdma_tx_status;
> @@ -941,6 +1101,7 @@ static int xdma_probe(struct platform_device *pdev)
>   	xdev->dma_dev.filter.map = pdata->device_map;
>   	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
>   	xdev->dma_dev.filter.fn = xdma_filter_fn;
> +	xdev->dma_dev.device_prep_dma_cyclic = xdma_prep_dma_cyclic;
>   
>   	ret = dma_async_device_register(&xdev->dma_dev);
>   	if (ret) {

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Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Miquel Raynal]

Hi Lizhi,

> > + * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
> > + * @chan: DMA channel pointer
> > + * @address: Device DMA address to access
> > + * @size: Total length to transfer
> > + * @period_size: Period size to use for each transfer
> > + * @dir: Transfer direction
> > + * @flags: Transfer ack flags
> > + */
> > +static struct dma_async_tx_descriptor *
> > +xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
> > +		     size_t size, size_t period_size,
> > +		     enum dma_transfer_direction dir,
> > +		     unsigned long flags)
> > +{
> > +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> > +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> > +	unsigned int periods = size / period_size;  

> What if size is not multiple of period_size?

Can this really happen? I would have expected a bug if size was not a
multiple of period_size, because the headers explicitly tell that we
should expect an interrupt after each period and we should loop over
when we reach the last one. This makes it very impractical to handle
the situation you mention.

> > +	struct dma_async_tx_descriptor *tx_desc;
> > +	u64 addr, dev_addr, *src, *dst;
> > +	struct xdma_desc_block *dblk;
> > +	struct xdma_hw_desc *desc;
> > +	struct xdma_desc *sw_desc;
> > +	unsigned int i;
> > +
> > +	/*
> > +	 * Simplify the whole logic by preventing an abnormally high number of
> > +	 * periods and periods size.
> > +	 */
> > +	if (period_size > XDMA_DESC_BLEN_MAX) {
> > +		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
> > +		return NULL;
> > +	}
> > +
> > +	if (periods > XDMA_DESC_ADJACENT) {
> > +		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
> > +		return NULL;
> > +	}
> > +
> > +	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
> > +	if (!sw_desc)
> > +		return NULL;
> > +
> > +	sw_desc->periods = periods;
> > +	sw_desc->period_size = period_size;
> > +	sw_desc->dir = dir;
> > +
> > +	if (dir == DMA_MEM_TO_DEV) {
> > +		dev_addr = xdma_chan->cfg.dst_addr;
> > +		src = &addr;
> > +		dst = &dev_addr;
> > +	} else {
> > +		dev_addr = xdma_chan->cfg.src_addr;
> > +		src = &dev_addr;
> > +		dst = &addr;
> > +	}
> > +
> > +	dblk = sw_desc->desc_blocks;
> > +	desc = dblk->virt_addr;
> > +	for (i = 0; i < periods; i++) {
> > +		addr = address;
> > +
> > +		/* fill hardware descriptor */
> > +		desc->bytes = cpu_to_le32(period_size);
> > +		desc->src_addr = cpu_to_le64(*src);
> > +		desc->dst_addr = cpu_to_le64(*dst);
> > +
> > +		desc++;
> > +		address += period_size;
> > +	}
> > +
> > +	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
> > +	if (!tx_desc)
> > +		goto failed;
> > +
> > +	return tx_desc;
> > +
> > +failed:
> > +	xdma_free_desc(&sw_desc->vdesc);
> > +
> > +	return NULL;
> > +}
> > +
> >   /**
> >    * xdma_device_config - Configure the DMA channel
> >    * @chan: DMA channel
> > @@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
> >   static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
> >   				      struct dma_tx_state *state)
> >   {
> > -	return dma_cookie_status(chan, cookie, state);
> > +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> > +	struct virt_dma_desc *vd;
> > +	struct xdma_desc *desc;
> > +	enum dma_status ret;
> > +	unsigned long flags;
> > +	unsigned int period_idx;
> > +	u32 residue = 0;
> > +
> > +	ret = dma_cookie_status(chan, cookie, state);
> > +	if (ret == DMA_COMPLETE || !state)  
>
> probably do not need to check state. Or at least check before calling dma_cookie_status.

Good idea.

> > +		return ret;
> > +
> > +	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
> > +
> > +	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
> > +	if (vd)
> > +		desc = to_xdma_desc(vd);
> > +	if (!desc || !desc->cyclic) {  
>
> desc is un-initialized if vd is NULL.

Yes, handled in v2.

> > +		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> > +		return ret;
> > +	}
> > +
> > +	period_idx = desc->completed_desc_num % desc->periods;
> > +	residue = (desc->periods - period_idx) * desc->period_size;
> > +
> > +	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> > +
> > +	dma_set_residue(state, residue);
> > +
> > +	return ret;
> >   }  
> >   >   /**  
> > @@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
> >   	struct virt_dma_desc *vd;
> >   	struct xdma_desc *desc;
> >   	int ret;
> > +	u32 st;  
> >   >   	spin_lock(&xchan->vchan.lock);
> >   > @@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)  
> >   		goto out;  
> >   >   	desc->completed_desc_num += complete_desc_num;  
> > +
> > +	if (desc->cyclic) {
> > +		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
> > +				  &st);
> > +		if (ret)
> > +			goto out;
> > +
> > +		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);  
> 
> What does reading/writing channel status register do here?

It clears the status register to allow the next interrupt to trigger.

Thanks,
Miquèl

Re: [PATCH 4/4] dmaengine: xilinx: xdma: Support cyclic transfers

[Miquel Raynal]

Hi Lizhi,

> > + * xdma_prep_dma_cyclic - prepare for cyclic DMA transactions
> > + * @chan: DMA channel pointer
> > + * @address: Device DMA address to access
> > + * @size: Total length to transfer
> > + * @period_size: Period size to use for each transfer
> > + * @dir: Transfer direction
> > + * @flags: Transfer ack flags
> > + */
> > +static struct dma_async_tx_descriptor *
> > +xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
> > +		     size_t size, size_t period_size,
> > +		     enum dma_transfer_direction dir,
> > +		     unsigned long flags)
> > +{
> > +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> > +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> > +	unsigned int periods = size / period_size;  

> What if size is not multiple of period_size?

Can this really happen? I would have expected a bug if size was not a
multiple of period_size, because the headers explicitly tell that we
should expect an interrupt after each period and we should loop over
when we reach the last one. This makes it very impractical to handle
the situation you mention.

> > +	struct dma_async_tx_descriptor *tx_desc;
> > +	u64 addr, dev_addr, *src, *dst;
> > +	struct xdma_desc_block *dblk;
> > +	struct xdma_hw_desc *desc;
> > +	struct xdma_desc *sw_desc;
> > +	unsigned int i;
> > +
> > +	/*
> > +	 * Simplify the whole logic by preventing an abnormally high number of
> > +	 * periods and periods size.
> > +	 */
> > +	if (period_size > XDMA_DESC_BLEN_MAX) {
> > +		xdma_err(xdev, "period size limited to %lu bytes\n", XDMA_DESC_BLEN_MAX);
> > +		return NULL;
> > +	}
> > +
> > +	if (periods > XDMA_DESC_ADJACENT) {
> > +		xdma_err(xdev, "number of periods limited to %u\n", XDMA_DESC_ADJACENT);
> > +		return NULL;
> > +	}
> > +
> > +	sw_desc = xdma_alloc_desc(xdma_chan, periods, true);
> > +	if (!sw_desc)
> > +		return NULL;
> > +
> > +	sw_desc->periods = periods;
> > +	sw_desc->period_size = period_size;
> > +	sw_desc->dir = dir;
> > +
> > +	if (dir == DMA_MEM_TO_DEV) {
> > +		dev_addr = xdma_chan->cfg.dst_addr;
> > +		src = &addr;
> > +		dst = &dev_addr;
> > +	} else {
> > +		dev_addr = xdma_chan->cfg.src_addr;
> > +		src = &dev_addr;
> > +		dst = &addr;
> > +	}
> > +
> > +	dblk = sw_desc->desc_blocks;
> > +	desc = dblk->virt_addr;
> > +	for (i = 0; i < periods; i++) {
> > +		addr = address;
> > +
> > +		/* fill hardware descriptor */
> > +		desc->bytes = cpu_to_le32(period_size);
> > +		desc->src_addr = cpu_to_le64(*src);
> > +		desc->dst_addr = cpu_to_le64(*dst);
> > +
> > +		desc++;
> > +		address += period_size;
> > +	}
> > +
> > +	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
> > +	if (!tx_desc)
> > +		goto failed;
> > +
> > +	return tx_desc;
> > +
> > +failed:
> > +	xdma_free_desc(&sw_desc->vdesc);
> > +
> > +	return NULL;
> > +}
> > +
> >   /**
> >    * xdma_device_config - Configure the DMA channel
> >    * @chan: DMA channel
> > @@ -583,7 +698,36 @@ static int xdma_alloc_chan_resources(struct dma_chan *chan)
> >   static enum dma_status xdma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
> >   				      struct dma_tx_state *state)
> >   {
> > -	return dma_cookie_status(chan, cookie, state);
> > +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> > +	struct virt_dma_desc *vd;
> > +	struct xdma_desc *desc;
> > +	enum dma_status ret;
> > +	unsigned long flags;
> > +	unsigned int period_idx;
> > +	u32 residue = 0;
> > +
> > +	ret = dma_cookie_status(chan, cookie, state);
> > +	if (ret == DMA_COMPLETE || !state)  
>
> probably do not need to check state. Or at least check before calling dma_cookie_status.

Good idea.

> > +		return ret;
> > +
> > +	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
> > +
> > +	vd = vchan_find_desc(&xdma_chan->vchan, cookie);
> > +	if (vd)
> > +		desc = to_xdma_desc(vd);
> > +	if (!desc || !desc->cyclic) {  
>
> desc is un-initialized if vd is NULL.

Yes, handled in v2.

> > +		spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> > +		return ret;
> > +	}
> > +
> > +	period_idx = desc->completed_desc_num % desc->periods;
> > +	residue = (desc->periods - period_idx) * desc->period_size;
> > +
> > +	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> > +
> > +	dma_set_residue(state, residue);
> > +
> > +	return ret;
> >   }  
> >   >   /**  
> > @@ -599,6 +743,7 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
> >   	struct virt_dma_desc *vd;
> >   	struct xdma_desc *desc;
> >   	int ret;
> > +	u32 st;  
> >   >   	spin_lock(&xchan->vchan.lock);
> >   > @@ -617,6 +762,19 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)  
> >   		goto out;  
> >   >   	desc->completed_desc_num += complete_desc_num;  
> > +
> > +	if (desc->cyclic) {
> > +		ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
> > +				  &st);
> > +		if (ret)
> > +			goto out;
> > +
> > +		regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_STATUS, st);  
> 
> What does reading/writing channel status register do here?

It clears the status register to allow the next interrupt to trigger.

Thanks,
Miquèl

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Re: (subset) [PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Vinod Koul]

On Mon, 31 Jul 2023 12:14:38 +0200, Miquel Raynal wrote:
> Following the introduction of scatter-gather support of Xilinx's XDMA IP
> in the Linux kernel, here is a small series adding cyclic transfers.
> 
> The first patch is a real bug fix which triggered in my case, the second
> just fixes a typo, the third one is a preparation patch to ease the
> review of the fourth one which actually adds cyclic transfers support.
> 
> [...]

Applied, thanks!

[1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting
      commit: d27a7028ba7214963eae3e3c266070a4a9f5725e
[2/4] dmaengine: xilinx: xdma: Fix typo
      commit: c3633b42923dae5c23a7fadaca6f10f8448b8fec

Best regards,
-- 
~Vinod

Re: (subset) [PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Vinod Koul]

On Mon, 31 Jul 2023 12:14:38 +0200, Miquel Raynal wrote:
> Following the introduction of scatter-gather support of Xilinx's XDMA IP
> in the Linux kernel, here is a small series adding cyclic transfers.
> 
> The first patch is a real bug fix which triggered in my case, the second
> just fixes a typo, the third one is a preparation patch to ease the
> review of the fourth one which actually adds cyclic transfers support.
> 
> [...]

Applied, thanks!

[1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting
      commit: d27a7028ba7214963eae3e3c266070a4a9f5725e
[2/4] dmaengine: xilinx: xdma: Fix typo
      commit: c3633b42923dae5c23a7fadaca6f10f8448b8fec

Best regards,
-- 
~Vinod



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Re: (subset) [PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Miquel Raynal]

Hi Vinod,

vkoul@kernel.org wrote on Wed, 02 Aug 2023 00:14:50 +0530:

> On Mon, 31 Jul 2023 12:14:38 +0200, Miquel Raynal wrote:
> > Following the introduction of scatter-gather support of Xilinx's XDMA IP
> > in the Linux kernel, here is a small series adding cyclic transfers.
> > 
> > The first patch is a real bug fix which triggered in my case, the second
> > just fixes a typo, the third one is a preparation patch to ease the
> > review of the fourth one which actually adds cyclic transfers support.
> > 
> > [...]  
> 
> Applied, thanks!
> 
> [1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting
>       commit: d27a7028ba7214963eae3e3c266070a4a9f5725e
> [2/4] dmaengine: xilinx: xdma: Fix typo
>       commit: c3633b42923dae5c23a7fadaca6f10f8448b8fec

Thanks!

I assume you will probably make additional remarks on patch 4/4, if
however you are waiting for a re-spin just let me know.

Cheers,
Miquèl

Re: (subset) [PATCH 0/4] dmaengine: xdma: Cyclic transfers support

[Miquel Raynal]

Hi Vinod,

vkoul@kernel.org wrote on Wed, 02 Aug 2023 00:14:50 +0530:

> On Mon, 31 Jul 2023 12:14:38 +0200, Miquel Raynal wrote:
> > Following the introduction of scatter-gather support of Xilinx's XDMA IP
> > in the Linux kernel, here is a small series adding cyclic transfers.
> > 
> > The first patch is a real bug fix which triggered in my case, the second
> > just fixes a typo, the third one is a preparation patch to ease the
> > review of the fourth one which actually adds cyclic transfers support.
> > 
> > [...]  
> 
> Applied, thanks!
> 
> [1/4] dmaengine: xilinx: xdma: Fix interrupt vector setting
>       commit: d27a7028ba7214963eae3e3c266070a4a9f5725e
> [2/4] dmaengine: xilinx: xdma: Fix typo
>       commit: c3633b42923dae5c23a7fadaca6f10f8448b8fec

Thanks!

I assume you will probably make additional remarks on patch 4/4, if
however you are waiting for a re-spin just let me know.

Cheers,
Miquèl

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