[PATCH v7 0/6] dmaengine: xilinx_dma: Bug fixes

[PATCH v7 0/6] dmaengine: xilinx_dma: Bug fixes

[Kedareswara rao Appana]

This patch series fixes below bugs in DMA and VDMA IP's
---> Added channel idle checks in the driver before submitting the buffer descriptor to h/w.
---> Fixes bug in Multi frame sotres handling in VDMA
---> Fixes issues w.r.to multi frame descriptors submit with AXI DMA S2MM(recv) Side.
---> Fixed kernel doc warnings in the driver.
---> Fixed checkpatch errors in the driver.

Kedareswara rao Appana (6):
  dmaengine: xilinx_dma: Check for channel idle state before submitting
    dma descriptor
  dmaeninge: xilinx_dma: Fix bug in multiple frame stores scenario in
    vdma
  dmaengine: xilinx_dma: Fix race condition in the driver for multiple
    descriptor scenario
  dmaengine: xilinx_dma: Fix kernel doc warnings
  dmaengine: xilinx_dma: fix style issues from checkpatch
  dmaengine: xilinx_dma: Differentiate probe based on the ip type

 drivers/dma/xilinx/xilinx_dma.c | 283 ++++++++++++++++++++++------------------
 1 file changed, 157 insertions(+), 126 deletions(-)

-- 
2.7.4

[PATCH v7 1/6] dmaengine: xilinx_dma: Check for channel idle state before submitting dma descriptor

[Kedareswara rao Appana]

Add variable for checking channel idle state to ensure that dma
descriptor is not submitted when dmaengine is in progress.

This will avoid the polling for a bit in the status register to know
dma state in the driver hot path.

Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
---> None.
Changes for v6:
---> Updated commit message as suggested by Vinod.
---> Added Channel idle variable description in the driver
     as suggested by Vinod.
Changes for v5:
---> None.
Changes for v4:
---> None.
Changes for v3:
---> None.
Changes for v2:
---> Add idle check in the reset as suggested by Jose Abreu
---> Removed xilinx_dma_is_running/xilinx_dma_is_idle checks
    in the driver and used common idle checks across the driver
    as suggested by Laurent Pinchart.

 drivers/dma/xilinx/xilinx_dma.c | 60 +++++++++++++++--------------------------
 1 file changed, 22 insertions(+), 38 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 5eef133..c246563 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -321,6 +321,7 @@ struct xilinx_dma_tx_descriptor {
  * @cyclic: Check for cyclic transfers.
  * @genlock: Support genlock mode
  * @err: Channel has errors
+ * @idle: Check for channel idle
  * @tasklet: Cleanup work after irq
  * @config: Device configuration info
  * @flush_on_fsync: Flush on Frame sync
@@ -352,6 +353,7 @@ struct xilinx_dma_chan {
 	bool cyclic;
 	bool genlock;
 	bool err;
+	bool idle;
 	struct tasklet_struct tasklet;
 	struct xilinx_vdma_config config;
 	bool flush_on_fsync;
@@ -936,32 +938,6 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
 }
 
 /**
- * xilinx_dma_is_running - Check if DMA channel is running
- * @chan: Driver specific DMA channel
- *
- * Return: '1' if running, '0' if not.
- */
-static bool xilinx_dma_is_running(struct xilinx_dma_chan *chan)
-{
-	return !(dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
-		 XILINX_DMA_DMASR_HALTED) &&
-		(dma_ctrl_read(chan, XILINX_DMA_REG_DMACR) &
-		 XILINX_DMA_DMACR_RUNSTOP);
-}
-
-/**
- * xilinx_dma_is_idle - Check if DMA channel is idle
- * @chan: Driver specific DMA channel
- *
- * Return: '1' if idle, '0' if not.
- */
-static bool xilinx_dma_is_idle(struct xilinx_dma_chan *chan)
-{
-	return dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
-		XILINX_DMA_DMASR_IDLE;
-}
-
-/**
  * xilinx_dma_stop_transfer - Halt DMA channel
  * @chan: Driver specific DMA channel
  */
@@ -1029,6 +1005,9 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 	if (chan->err)
 		return;
 
+	if (!chan->idle)
+		return;
+
 	if (list_empty(&chan->pending_list))
 		return;
 
@@ -1040,13 +1019,6 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 	tail_segment = list_last_entry(&tail_desc->segments,
 				       struct xilinx_vdma_tx_segment, node);
 
-	/* If it is SG mode and hardware is busy, cannot submit */
-	if (chan->has_sg && xilinx_dma_is_running(chan) &&
-	    !xilinx_dma_is_idle(chan)) {
-		dev_dbg(chan->dev, "DMA controller still busy\n");
-		return;
-	}
-
 	/*
 	 * If hardware is idle, then all descriptors on the running lists are
 	 * done, start new transfers
@@ -1143,6 +1115,8 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 		list_splice_tail_init(&chan->pending_list, &chan->active_list);
 		chan->desc_pendingcount = 0;
 	}
+
+	chan->idle = false;
 }
 
 /**
@@ -1158,6 +1132,9 @@ static void xilinx_cdma_start_transfer(struct xilinx_dma_chan *chan)
 	if (chan->err)
 		return;
 
+	if (!chan->idle)
+		return;
+
 	if (list_empty(&chan->pending_list))
 		return;
 
@@ -1203,6 +1180,7 @@ static void xilinx_cdma_start_transfer(struct xilinx_dma_chan *chan)
 
 	list_splice_tail_init(&chan->pending_list, &chan->active_list);
 	chan->desc_pendingcount = 0;
+	chan->idle = false;
 }
 
 /**
@@ -1221,12 +1199,8 @@ static void xilinx_dma_start_transfer(struct xilinx_dma_chan *chan)
 	if (list_empty(&chan->pending_list))
 		return;
 
-	/* If it is SG mode and hardware is busy, cannot submit */
-	if (chan->has_sg && xilinx_dma_is_running(chan) &&
-	    !xilinx_dma_is_idle(chan)) {
-		dev_dbg(chan->dev, "DMA controller still busy\n");
+	if (!chan->idle)
 		return;
-	}
 
 	head_desc = list_first_entry(&chan->pending_list,
 				     struct xilinx_dma_tx_descriptor, node);
@@ -1324,6 +1298,7 @@ static void xilinx_dma_start_transfer(struct xilinx_dma_chan *chan)
 
 	list_splice_tail_init(&chan->pending_list, &chan->active_list);
 	chan->desc_pendingcount = 0;
+	chan->idle = false;
 }
 
 /**
@@ -1388,6 +1363,7 @@ static int xilinx_dma_reset(struct xilinx_dma_chan *chan)
 	}
 
 	chan->err = false;
+	chan->idle = true;
 
 	return err;
 }
@@ -1469,6 +1445,7 @@ static irqreturn_t xilinx_dma_irq_handler(int irq, void *data)
 	if (status & XILINX_DMA_DMASR_FRM_CNT_IRQ) {
 		spin_lock(&chan->lock);
 		xilinx_dma_complete_descriptor(chan);
+		chan->idle = true;
 		chan->start_transfer(chan);
 		spin_unlock(&chan->lock);
 	}
@@ -2029,6 +2006,7 @@ static int xilinx_dma_terminate_all(struct dma_chan *dchan)
 
 	/* Remove and free all of the descriptors in the lists */
 	xilinx_dma_free_descriptors(chan);
+	chan->idle = true;
 
 	if (chan->cyclic) {
 		reg = dma_ctrl_read(chan, XILINX_DMA_REG_DMACR);
@@ -2344,6 +2322,12 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 	chan->has_sg = xdev->has_sg;
 	chan->desc_pendingcount = 0x0;
 	chan->ext_addr = xdev->ext_addr;
+	/* This variable enusres that descripotrs are not
+	 * Submited when dma engine is in progress. This variable is
+	 * Added to avoid pollling for a bit in the status register to
+	 * Know dma state in the driver hot path.
+	 */
+	chan->idle = true;
 
 	spin_lock_init(&chan->lock);
 	INIT_LIST_HEAD(&chan->pending_list);
-- 
2.7.4

[PATCH v7 2/6] dmaeninge: xilinx_dma: Fix bug in multiple frame stores scenario in vdma

[Kedareswara rao Appana]

VDMA engine default frame buffer configuration is cirular mode.
in this mode dmaengine continuously circles through h/w configured fstore
frame buffers.

When vdma h/w is configured for more than one frame.
for example h/w is configured for n number of frames, user
submits less than n number of frames and triggered the dmaengine
using issue_pending API.

since the h/w (or) driver default configuraiton is circular mode
h/w tries to write/read from an invalid frame buffer resulting
errors from the vdma dmaengine.

This patch fixes this issue by enabling the park mode as
default mode configuration for frame buffers in s/w,
so that driver can handle all cases for "k" frames where n%k==0
(n is a multiple of k) by simply replicating the frame pointers.

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
---> Used park mode as default configuration as suggested
by Mike Looijmans.
---> Updated commit message as suggested by Vinod(No need to
start each line with Title cases).
Changes for v6:
---> Added Rob Acked-by
---> Updated commit message as suggested by Vinod.
Changes for v5:
---> Updated xlnx,fstore-config property to xlnx,fstore-enable
     and updated description as suggested by Rob.
Changes for v4:
---> Add Check for framestore configuration on Transmit case as well
     as suggested by Jose Abreu.
---> Modified the dev_dbg checks to dev_warn checks as suggested
     by Jose Abreu.
Changes for v3:
---> Added Checks for frame store configuration. If frame store
     Configuration is not present at the h/w level and user
     Submits less frames added debug prints in the driver as relevant.
Changes for v2:
---> Fixed race conditions in the driver as suggested by Jose Abreu
---> Fixed unnecessray if else checks in the vdma_start_transfer
     as suggested by Laurent Pinchart.

 drivers/dma/xilinx/xilinx_dma.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index c246563..9063ca0 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -99,7 +99,9 @@
 #define XILINX_DMA_REG_FRMPTR_STS		0x0024
 #define XILINX_DMA_REG_PARK_PTR		0x0028
 #define XILINX_DMA_PARK_PTR_WR_REF_SHIFT	8
+#define XILINX_DMA_PARK_PTR_WR_REF_MASK		GENMASK(12, 8)
 #define XILINX_DMA_PARK_PTR_RD_REF_SHIFT	0
+#define XILINX_DMA_PARK_PTR_RD_REF_MASK		GENMASK(4, 0)
 #define XILINX_DMA_REG_VDMA_VERSION		0x002c
 
 /* Register Direct Mode Registers */
@@ -998,7 +1000,7 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 {
 	struct xilinx_vdma_config *config = &chan->config;
 	struct xilinx_dma_tx_descriptor *desc, *tail_desc;
-	u32 reg;
+	u32 reg, j;
 	struct xilinx_vdma_tx_segment *tail_segment;
 
 	/* This function was invoked with lock held */
@@ -1035,10 +1037,6 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 	else
 		reg &= ~XILINX_DMA_DMACR_FRAMECNT_EN;
 
-	/* Configure channel to allow number frame buffers */
-	dma_ctrl_write(chan, XILINX_DMA_REG_FRMSTORE,
-			chan->desc_pendingcount);
-
 	/*
 	 * With SG, start with circular mode, so that BDs can be fetched.
 	 * In direct register mode, if not parking, enable circular mode
@@ -1051,17 +1049,16 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 
 	dma_ctrl_write(chan, XILINX_DMA_REG_DMACR, reg);
 
-	if (config->park && (config->park_frm >= 0) &&
-			(config->park_frm < chan->num_frms)) {
-		if (chan->direction == DMA_MEM_TO_DEV)
-			dma_write(chan, XILINX_DMA_REG_PARK_PTR,
-				config->park_frm <<
-					XILINX_DMA_PARK_PTR_RD_REF_SHIFT);
-		else
-			dma_write(chan, XILINX_DMA_REG_PARK_PTR,
-				config->park_frm <<
-					XILINX_DMA_PARK_PTR_WR_REF_SHIFT);
+	j = chan->desc_submitcount;
+	reg = dma_read(chan, XILINX_DMA_REG_PARK_PTR);
+	if (chan->direction == DMA_MEM_TO_DEV) {
+		reg &= ~XILINX_DMA_PARK_PTR_RD_REF_MASK;
+		reg |= j << XILINX_DMA_PARK_PTR_RD_REF_SHIFT;
+	} else {
+		reg &= ~XILINX_DMA_PARK_PTR_WR_REF_MASK;
+		reg |= j << XILINX_DMA_PARK_PTR_WR_REF_SHIFT;
 	}
+	dma_write(chan, XILINX_DMA_REG_PARK_PTR, reg);
 
 	/* Start the hardware */
 	xilinx_dma_start(chan);
@@ -1073,6 +1070,8 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 	if (chan->has_sg) {
 		dma_ctrl_write(chan, XILINX_DMA_REG_TAILDESC,
 				tail_segment->phys);
+		list_splice_tail_init(&chan->pending_list, &chan->active_list);
+		chan->desc_pendingcount = 0;
 	} else {
 		struct xilinx_vdma_tx_segment *segment, *last = NULL;
 		int i = 0;
@@ -1102,18 +1101,13 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 		vdma_desc_write(chan, XILINX_DMA_REG_FRMDLY_STRIDE,
 				last->hw.stride);
 		vdma_desc_write(chan, XILINX_DMA_REG_VSIZE, last->hw.vsize);
-	}
 
-	if (!chan->has_sg) {
-		list_del(&desc->node);
-		list_add_tail(&desc->node, &chan->active_list);
 		chan->desc_submitcount++;
 		chan->desc_pendingcount--;
+		list_del(&desc->node);
+		list_add_tail(&desc->node, &chan->active_list);
 		if (chan->desc_submitcount == chan->num_frms)
 			chan->desc_submitcount = 0;
-	} else {
-		list_splice_tail_init(&chan->pending_list, &chan->active_list);
-		chan->desc_pendingcount = 0;
 	}
 
 	chan->idle = false;
@@ -1364,6 +1358,7 @@ static int xilinx_dma_reset(struct xilinx_dma_chan *chan)
 
 	chan->err = false;
 	chan->idle = true;
+	chan->desc_submitcount = 0;
 
 	return err;
 }
@@ -2363,6 +2358,7 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 		chan->ctrl_offset = XILINX_DMA_MM2S_CTRL_OFFSET;
 		if (xdev->dma_config->dmatype == XDMA_TYPE_VDMA) {
 			chan->desc_offset = XILINX_VDMA_MM2S_DESC_OFFSET;
+			chan->config.park = 1;
 
 			if (xdev->flush_on_fsync == XILINX_DMA_FLUSH_BOTH ||
 			    xdev->flush_on_fsync == XILINX_DMA_FLUSH_MM2S)
@@ -2379,6 +2375,7 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 		chan->ctrl_offset = XILINX_DMA_S2MM_CTRL_OFFSET;
 		if (xdev->dma_config->dmatype == XDMA_TYPE_VDMA) {
 			chan->desc_offset = XILINX_VDMA_S2MM_DESC_OFFSET;
+			chan->config.park = 1;
 
 			if (xdev->flush_on_fsync == XILINX_DMA_FLUSH_BOTH ||
 			    xdev->flush_on_fsync == XILINX_DMA_FLUSH_S2MM)
-- 
2.7.4

[PATCH v7 3/6] dmaengine: xilinx_dma: Fix race condition in the driver for multiple descriptor scenario

[Kedareswara rao Appana]

As per axi dmaengine spec the software must not move the tail pointer
to a location that has not been updated (next descriptor field of the
h/w descriptor should always point to a valid address).

When user submits multiple descriptors on the recv side, with the
current driver flow the last buffer descriptor next descriptor field
points to a invalid location, resulting the invalid data or errors from the
axidma dmaengine.

This patch fixes this issue by creating a buffer descritpor chain during
channel allocation itself and use those buffer descriptors for the
subsequent dma operations.

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
---> None.
Changes for v6:
---> Updated Commit message as suggested by Vinod.
Changes for v5:
---> None.
Changes for v4:
---> None.
Changes for v3:
---> None.
Changes for v2:
---> None.

 drivers/dma/xilinx/xilinx_dma.c | 135 +++++++++++++++++++++++++---------------
 1 file changed, 84 insertions(+), 51 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 9063ca0..ab01306 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -165,6 +165,7 @@
 #define XILINX_DMA_BD_SOP		BIT(27)
 #define XILINX_DMA_BD_EOP		BIT(26)
 #define XILINX_DMA_COALESCE_MAX		255
+#define XILINX_DMA_NUM_DESCS		255
 #define XILINX_DMA_NUM_APP_WORDS	5
 
 /* Multi-Channel DMA Descriptor offsets*/
@@ -312,6 +313,7 @@ struct xilinx_dma_tx_descriptor {
  * @pending_list: Descriptors waiting
  * @active_list: Descriptors ready to submit
  * @done_list: Complete descriptors
+ * @free_seg_list: Free descriptors
  * @common: DMA common channel
  * @desc_pool: Descriptors pool
  * @dev: The dma device
@@ -332,7 +334,9 @@ struct xilinx_dma_tx_descriptor {
  * @desc_submitcount: Descriptor h/w submitted count
  * @residue: Residue for AXI DMA
  * @seg_v: Statically allocated segments base
+ * @seg_p: Physical allocated segments base
  * @cyclic_seg_v: Statically allocated segment base for cyclic transfers
+ * @cyclic_seg_p: Physical allocated segments base for cyclic dma
  * @start_transfer: Differentiate b/w DMA IP's transfer
  * @stop_transfer: Differentiate b/w DMA IP's quiesce
  */
@@ -344,6 +348,7 @@ struct xilinx_dma_chan {
 	struct list_head pending_list;
 	struct list_head active_list;
 	struct list_head done_list;
+	struct list_head free_seg_list;
 	struct dma_chan common;
 	struct dma_pool *desc_pool;
 	struct device *dev;
@@ -364,7 +369,9 @@ struct xilinx_dma_chan {
 	u32 desc_submitcount;
 	u32 residue;
 	struct xilinx_axidma_tx_segment *seg_v;
+	dma_addr_t seg_p;
 	struct xilinx_axidma_tx_segment *cyclic_seg_v;
+	dma_addr_t cyclic_seg_p;
 	void (*start_transfer)(struct xilinx_dma_chan *chan);
 	int (*stop_transfer)(struct xilinx_dma_chan *chan);
 	u16 tdest;
@@ -584,18 +591,32 @@ xilinx_cdma_alloc_tx_segment(struct xilinx_dma_chan *chan)
 static struct xilinx_axidma_tx_segment *
 xilinx_axidma_alloc_tx_segment(struct xilinx_dma_chan *chan)
 {
-	struct xilinx_axidma_tx_segment *segment;
-	dma_addr_t phys;
-
-	segment = dma_pool_zalloc(chan->desc_pool, GFP_ATOMIC, &phys);
-	if (!segment)
-		return NULL;
+	struct xilinx_axidma_tx_segment *segment = NULL;
+	unsigned long flags;
 
-	segment->phys = phys;
+	spin_lock_irqsave(&chan->lock, flags);
+	if (!list_empty(&chan->free_seg_list)) {
+		segment = list_first_entry(&chan->free_seg_list,
+					   struct xilinx_axidma_tx_segment,
+					   node);
+		list_del(&segment->node);
+	}
+	spin_unlock_irqrestore(&chan->lock, flags);
 
 	return segment;
 }
 
+static void xilinx_dma_clean_hw_desc(struct xilinx_axidma_desc_hw *hw)
+{
+	u32 next_desc = hw->next_desc;
+	u32 next_desc_msb = hw->next_desc_msb;
+
+	memset(hw, 0, sizeof(struct xilinx_axidma_desc_hw));
+
+	hw->next_desc = next_desc;
+	hw->next_desc_msb = next_desc_msb;
+}
+
 /**
  * xilinx_dma_free_tx_segment - Free transaction segment
  * @chan: Driver specific DMA channel
@@ -604,7 +625,9 @@ xilinx_axidma_alloc_tx_segment(struct xilinx_dma_chan *chan)
 static void xilinx_dma_free_tx_segment(struct xilinx_dma_chan *chan,
 				struct xilinx_axidma_tx_segment *segment)
 {
-	dma_pool_free(chan->desc_pool, segment, segment->phys);
+	xilinx_dma_clean_hw_desc(&segment->hw);
+
+	list_add_tail(&segment->node, &chan->free_seg_list);
 }
 
 /**
@@ -729,16 +752,26 @@ static void xilinx_dma_free_descriptors(struct xilinx_dma_chan *chan)
 static void xilinx_dma_free_chan_resources(struct dma_chan *dchan)
 {
 	struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
+	unsigned long flags;
 
 	dev_dbg(chan->dev, "Free all channel resources.\n");
 
 	xilinx_dma_free_descriptors(chan);
+
 	if (chan->xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
-		xilinx_dma_free_tx_segment(chan, chan->cyclic_seg_v);
-		xilinx_dma_free_tx_segment(chan, chan->seg_v);
+		spin_lock_irqsave(&chan->lock, flags);
+		INIT_LIST_HEAD(&chan->free_seg_list);
+		spin_unlock_irqrestore(&chan->lock, flags);
+
+		/* Free Memory that is allocated for cyclic DMA Mode */
+		dma_free_coherent(chan->dev, sizeof(*chan->cyclic_seg_v),
+				  chan->cyclic_seg_v, chan->cyclic_seg_p);
+	}
+
+	if (chan->xdev->dma_config->dmatype != XDMA_TYPE_AXIDMA) {
+		dma_pool_destroy(chan->desc_pool);
+		chan->desc_pool = NULL;
 	}
-	dma_pool_destroy(chan->desc_pool);
-	chan->desc_pool = NULL;
 }
 
 /**
@@ -821,6 +854,7 @@ static void xilinx_dma_do_tasklet(unsigned long data)
 static int xilinx_dma_alloc_chan_resources(struct dma_chan *dchan)
 {
 	struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
+	int i;
 
 	/* Has this channel already been allocated? */
 	if (chan->desc_pool)
@@ -831,11 +865,30 @@ static int xilinx_dma_alloc_chan_resources(struct dma_chan *dchan)
 	 * for meeting Xilinx VDMA specification requirement.
 	 */
 	if (chan->xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
-		chan->desc_pool = dma_pool_create("xilinx_dma_desc_pool",
-				   chan->dev,
-				   sizeof(struct xilinx_axidma_tx_segment),
-				   __alignof__(struct xilinx_axidma_tx_segment),
-				   0);
+		/* Allocate the buffer descriptors. */
+		chan->seg_v = dma_zalloc_coherent(chan->dev,
+						  sizeof(*chan->seg_v) *
+						  XILINX_DMA_NUM_DESCS,
+						  &chan->seg_p, GFP_KERNEL);
+		if (!chan->seg_v) {
+			dev_err(chan->dev,
+				"unable to allocate channel %d descriptors\n",
+				chan->id);
+			return -ENOMEM;
+		}
+
+		for (i = 0; i < XILINX_DMA_NUM_DESCS; i++) {
+			chan->seg_v[i].hw.next_desc =
+			lower_32_bits(chan->seg_p + sizeof(*chan->seg_v) *
+				((i + 1) % XILINX_DMA_NUM_DESCS));
+			chan->seg_v[i].hw.next_desc_msb =
+			upper_32_bits(chan->seg_p + sizeof(*chan->seg_v) *
+				((i + 1) % XILINX_DMA_NUM_DESCS));
+			chan->seg_v[i].phys = chan->seg_p +
+				sizeof(*chan->seg_v) * i;
+			list_add_tail(&chan->seg_v[i].node,
+				      &chan->free_seg_list);
+		}
 	} else if (chan->xdev->dma_config->dmatype == XDMA_TYPE_CDMA) {
 		chan->desc_pool = dma_pool_create("xilinx_cdma_desc_pool",
 				   chan->dev,
@@ -850,7 +903,8 @@ static int xilinx_dma_alloc_chan_resources(struct dma_chan *dchan)
 				     0);
 	}
 
-	if (!chan->desc_pool) {
+	if (!chan->desc_pool &&
+	    (chan->xdev->dma_config->dmatype != XDMA_TYPE_AXIDMA)) {
 		dev_err(chan->dev,
 			"unable to allocate channel %d descriptor pool\n",
 			chan->id);
@@ -859,22 +913,20 @@ static int xilinx_dma_alloc_chan_resources(struct dma_chan *dchan)
 
 	if (chan->xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
 		/*
-		 * For AXI DMA case after submitting a pending_list, keep
-		 * an extra segment allocated so that the "next descriptor"
-		 * pointer on the tail descriptor always points to a
-		 * valid descriptor, even when paused after reaching taildesc.
-		 * This way, it is possible to issue additional
-		 * transfers without halting and restarting the channel.
-		 */
-		chan->seg_v = xilinx_axidma_alloc_tx_segment(chan);
-
-		/*
 		 * For cyclic DMA mode we need to program the tail Descriptor
 		 * register with a value which is not a part of the BD chain
 		 * so allocating a desc segment during channel allocation for
 		 * programming tail descriptor.
 		 */
-		chan->cyclic_seg_v = xilinx_axidma_alloc_tx_segment(chan);
+		chan->cyclic_seg_v = dma_zalloc_coherent(chan->dev,
+					sizeof(*chan->cyclic_seg_v),
+					&chan->cyclic_seg_p, GFP_KERNEL);
+		if (!chan->cyclic_seg_v) {
+			dev_err(chan->dev,
+				"unable to allocate desc segment for cyclic DMA\n");
+			return -ENOMEM;
+		}
+		chan->cyclic_seg_v->phys = chan->cyclic_seg_p;
 	}
 
 	dma_cookie_init(dchan);
@@ -1184,7 +1236,7 @@ static void xilinx_cdma_start_transfer(struct xilinx_dma_chan *chan)
 static void xilinx_dma_start_transfer(struct xilinx_dma_chan *chan)
 {
 	struct xilinx_dma_tx_descriptor *head_desc, *tail_desc;
-	struct xilinx_axidma_tx_segment *tail_segment, *old_head, *new_head;
+	struct xilinx_axidma_tx_segment *tail_segment;
 	u32 reg;
 
 	if (chan->err)
@@ -1203,21 +1255,6 @@ static void xilinx_dma_start_transfer(struct xilinx_dma_chan *chan)
 	tail_segment = list_last_entry(&tail_desc->segments,
 				       struct xilinx_axidma_tx_segment, node);
 
-	if (chan->has_sg && !chan->xdev->mcdma) {
-		old_head = list_first_entry(&head_desc->segments,
-					struct xilinx_axidma_tx_segment, node);
-		new_head = chan->seg_v;
-		/* Copy Buffer Descriptor fields. */
-		new_head->hw = old_head->hw;
-
-		/* Swap and save new reserve */
-		list_replace_init(&old_head->node, &new_head->node);
-		chan->seg_v = old_head;
-
-		tail_segment->hw.next_desc = chan->seg_v->phys;
-		head_desc->async_tx.phys = new_head->phys;
-	}
-
 	reg = dma_ctrl_read(chan, XILINX_DMA_REG_DMACR);
 
 	if (chan->desc_pendingcount <= XILINX_DMA_COALESCE_MAX) {
@@ -1705,7 +1742,7 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
 {
 	struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
 	struct xilinx_dma_tx_descriptor *desc;
-	struct xilinx_axidma_tx_segment *segment = NULL, *prev = NULL;
+	struct xilinx_axidma_tx_segment *segment = NULL;
 	u32 *app_w = (u32 *)context;
 	struct scatterlist *sg;
 	size_t copy;
@@ -1756,10 +1793,6 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
 					       XILINX_DMA_NUM_APP_WORDS);
 			}
 
-			if (prev)
-				prev->hw.next_desc = segment->phys;
-
-			prev = segment;
 			sg_used += copy;
 
 			/*
@@ -1773,7 +1806,6 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
 	segment = list_first_entry(&desc->segments,
 				   struct xilinx_axidma_tx_segment, node);
 	desc->async_tx.phys = segment->phys;
-	prev->hw.next_desc = segment->phys;
 
 	/* For the last DMA_MEM_TO_DEV transfer, set EOP */
 	if (chan->direction == DMA_MEM_TO_DEV) {
@@ -2328,6 +2360,7 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 	INIT_LIST_HEAD(&chan->pending_list);
 	INIT_LIST_HEAD(&chan->done_list);
 	INIT_LIST_HEAD(&chan->active_list);
+	INIT_LIST_HEAD(&chan->free_seg_list);
 
 	/* Retrieve the channel properties from the device tree */
 	has_dre = of_property_read_bool(node, "xlnx,include-dre");
-- 
2.7.4

[PATCH v7 4/6] dmaengine: xilinx_dma: Fix kernel doc warnings

[Kedareswara rao Appana]

This patch fixes the kernel doc warnings
in the driver.

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
--> New patch.

 drivers/dma/xilinx/xilinx_dma.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index ab01306..eaa93fe 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -214,8 +214,8 @@ struct xilinx_vdma_desc_hw {
  * @next_desc_msb: MSB of Next Descriptor Pointer @0x04
  * @buf_addr: Buffer address @0x08
  * @buf_addr_msb: MSB of Buffer address @0x0C
- * @pad1: Reserved @0x10
- * @pad2: Reserved @0x14
+ * @mcdma_control: Control field for mcdma @0x10
+ * @vsize_stride: Vsize and Stride field for mcdma @0x14
  * @control: Control field @0x18
  * @status: Status field @0x1C
  * @app: APP Fields @0x20 - 0x30
@@ -235,11 +235,11 @@ struct xilinx_axidma_desc_hw {
 /**
  * struct xilinx_cdma_desc_hw - Hardware Descriptor
  * @next_desc: Next Descriptor Pointer @0x00
- * @next_descmsb: Next Descriptor Pointer MSB @0x04
+ * @next_desc_msb: Next Descriptor Pointer MSB @0x04
  * @src_addr: Source address @0x08
- * @src_addrmsb: Source address MSB @0x0C
+ * @src_addr_msb: Source address MSB @0x0C
  * @dest_addr: Destination address @0x10
- * @dest_addrmsb: Destination address MSB @0x14
+ * @dest_addr_msb: Destination address MSB @0x14
  * @control: Control field @0x18
  * @status: Status field @0x1C
  */
@@ -339,6 +339,7 @@ struct xilinx_dma_tx_descriptor {
  * @cyclic_seg_p: Physical allocated segments base for cyclic dma
  * @start_transfer: Differentiate b/w DMA IP's transfer
  * @stop_transfer: Differentiate b/w DMA IP's quiesce
+ * @tdest: TDEST value for mcdma
  */
 struct xilinx_dma_chan {
 	struct xilinx_dma_device *xdev;
@@ -378,11 +379,11 @@ struct xilinx_dma_chan {
 };
 
 /**
- * enum xdma_ip_type: DMA IP type.
+ * enum xdma_ip_type - DMA IP type.
  *
- * XDMA_TYPE_AXIDMA: Axi dma ip.
- * XDMA_TYPE_CDMA: Axi cdma ip.
- * XDMA_TYPE_VDMA: Axi vdma ip.
+ * @XDMA_TYPE_AXIDMA: Axi dma ip.
+ * @XDMA_TYPE_CDMA: Axi cdma ip.
+ * @XDMA_TYPE_VDMA: Axi vdma ip.
  *
  */
 enum xdma_ip_type {
@@ -994,6 +995,8 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
 /**
  * xilinx_dma_stop_transfer - Halt DMA channel
  * @chan: Driver specific DMA channel
+ *
+ * Return: '0' on success and failure value on error
  */
 static int xilinx_dma_stop_transfer(struct xilinx_dma_chan *chan)
 {
@@ -1010,6 +1013,8 @@ static int xilinx_dma_stop_transfer(struct xilinx_dma_chan *chan)
 /**
  * xilinx_cdma_stop_transfer - Wait for the current transfer to complete
  * @chan: Driver specific DMA channel
+ *
+ * Return: '0' on success and failure value on error
  */
 static int xilinx_cdma_stop_transfer(struct xilinx_dma_chan *chan)
 {
@@ -1825,11 +1830,14 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
 
 /**
  * xilinx_dma_prep_dma_cyclic - prepare descriptors for a DMA_SLAVE transaction
- * @chan: DMA channel
- * @sgl: scatterlist to transfer to/from
- * @sg_len: number of entries in @scatterlist
+ * @dchan: DMA channel
+ * @buf_addr: Physical address of the buffer
+ * @buf_len: Total length of the cyclic buffers
+ * @period_len: length of individual cyclic buffer
  * @direction: DMA direction
  * @flags: transfer ack flags
+ *
+ * Return: Async transaction descriptor on success and NULL on failure
  */
 static struct dma_async_tx_descriptor *xilinx_dma_prep_dma_cyclic(
 	struct dma_chan *dchan, dma_addr_t buf_addr, size_t buf_len,
@@ -2013,7 +2021,9 @@ xilinx_dma_prep_interleaved(struct dma_chan *dchan,
 
 /**
  * xilinx_dma_terminate_all - Halt the channel and free descriptors
- * @chan: Driver specific DMA Channel pointer
+ * @dchan: Driver specific DMA Channel pointer
+ *
+ * Return: '0' always.
  */
 static int xilinx_dma_terminate_all(struct dma_chan *dchan)
 {
@@ -2328,6 +2338,7 @@ static void xdma_disable_allclks(struct xilinx_dma_device *xdev)
  *
  * @xdev: Driver specific device structure
  * @node: Device node
+ * @chan_id: DMA Channel id
  *
  * Return: '0' on success and failure value on error
  */
-- 
2.7.4

[PATCH v7 5/6] dmaengine: xilinx_dma: fix style issues from checkpatch

[Kedareswara rao Appana]

This patch fixes below.
ERROR: open brace '{' following function definitions go on the next line
+static int xilinx_dma_child_probe(struct xilinx_dma_device *xdev,
+				    struct device_node *node) {

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
--> New patch.

 drivers/dma/xilinx/xilinx_dma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index eaa93fe..b09a8ef 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -2484,7 +2484,8 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
  * Return: 0 always.
  */
 static int xilinx_dma_child_probe(struct xilinx_dma_device *xdev,
-				    struct device_node *node) {
+				    struct device_node *node)
+{
 	int ret, i, nr_channels = 1;
 
 	ret = of_property_read_u32(node, "dma-channels", &nr_channels);
-- 
2.7.4

[PATCH v7 6/6] dmaengine: xilinx_dma: Differentiate probe based on the ip type

[Kedareswara rao Appana]

This patch updates the probe banner info based on the ip probed.

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
Changes for v7:
--> New patch.

 drivers/dma/xilinx/xilinx_dma.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index b09a8ef..52e2f18 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -2680,7 +2680,12 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 		goto error;
 	}
 
-	dev_info(&pdev->dev, "Xilinx AXI VDMA Engine Driver Probed!!\n");
+	if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA)
+		dev_info(&pdev->dev, "Xilinx AXI DMA Engine Driver Probed!!\n");
+	else if (xdev->dma_config->dmatype == XDMA_TYPE_CDMA)
+		dev_info(&pdev->dev, "Xilinx AXI CDMA Engine Driver Probed!!\n");
+	else
+		dev_info(&pdev->dev, "Xilinx AXI VDMA Engine Driver Probed!!\n");
 
 	return 0;
 
-- 
2.7.4

[PATCH v7 1/6] dmaengine: xilinx_dma: Check for channel idle state before submitting dma descriptor

[Vinod Koul]

On Thu, Dec 07, 2017 at 10:51:02AM +0530, Kedareswara rao Appana wrote:

> @@ -2029,6 +2006,7 @@ static int xilinx_dma_terminate_all(struct dma_chan *dchan)
>  
>  	/* Remove and free all of the descriptors in the lists */
>  	xilinx_dma_free_descriptors(chan);
> +	chan->idle = true;
>  
>  	if (chan->cyclic) {
>  		reg = dma_ctrl_read(chan, XILINX_DMA_REG_DMACR);
> @@ -2344,6 +2322,12 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>  	chan->has_sg = xdev->has_sg;
>  	chan->desc_pendingcount = 0x0;
>  	chan->ext_addr = xdev->ext_addr;
> +	/* This variable enusres that descripotrs are not
				      ^^^^^^^^^^

typo

-- 
~Vinod

[PATCH v7 0/6] dmaengine: xilinx_dma: Bug fixes

[Vinod Koul]

On Thu, Dec 07, 2017 at 10:51:01AM +0530, Kedareswara rao Appana wrote:
> This patch series fixes below bugs in DMA and VDMA IP's
> ---> Added channel idle checks in the driver before submitting the buffer descriptor to h/w.
> ---> Fixes bug in Multi frame sotres handling in VDMA
> ---> Fixes issues w.r.to multi frame descriptors submit with AXI DMA S2MM(recv) Side.
> ---> Fixed kernel doc warnings in the driver.
> ---> Fixed checkpatch errors in the driver.

Applied after applying this to fix typo. You seriously need a decent spell
checker in your editor

-       /* This variable enusres that descripotrs are not
-        * Submited when dma engine is in progress. This variable is
-        * Added to avoid pollling for a bit in the status register to
+       /* This variable ensures that descriptors are not
+        * Submitted when dma engine is in progress. This variable is
+        * Added to avoid polling for a bit in the status register to

-- 
~Vinod

[PATCH v7 0/6] dmaengine: xilinx_dma: Bug fixes

[Appana Durga Kedareswara Rao]

Hi Vinod,

>
>On Thu, Dec 07, 2017 at 10:51:01AM +0530, Kedareswara rao Appana wrote:
>> This patch series fixes below bugs in DMA and VDMA IP's
>> ---> Added channel idle checks in the driver before submitting the buffer
>descriptor to h/w.
>> ---> Fixes bug in Multi frame sotres handling in VDMA Fixes issues
>> ---> w.r.to multi frame descriptors submit with AXI DMA S2MM(recv) Side.
>> ---> Fixed kernel doc warnings in the driver.
>> ---> Fixed checkpatch errors in the driver.
>
>Applied after applying this to fix typo. You seriously need a decent spell checker in
>your editor

Thanks Vinod
Sorry for the noise around spell checks.
Will take care of it next time onwards thanks for pointing it out. 

Regards,
Kedar.

>
>-       /* This variable enusres that descripotrs are not
>-        * Submited when dma engine is in progress. This variable is
>-        * Added to avoid pollling for a bit in the status register to
>+       /* This variable ensures that descriptors are not
>+        * Submitted when dma engine is in progress. This variable is
>+        * Added to avoid polling for a bit in the status register to
>
>--
>~Vinod
>--
>To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body
>of a message to majordomo at vger.kernel.org More majordomo info at
>http://vger.kernel.org/majordomo-info.html

[PATCH v7 1/6] dmaengine: xilinx_dma: Check for channel idle state before submitting dma descriptor

[Appana Durga Kedareswara Rao]

Hi,

	Thanks for the review...

<Snip>
>
>On Thu, Dec 07, 2017 at 10:51:02AM +0530, Kedareswara rao Appana wrote:
>
>> @@ -2029,6 +2006,7 @@ static int xilinx_dma_terminate_all(struct
>> dma_chan *dchan)
>>
>>  	/* Remove and free all of the descriptors in the lists */
>>  	xilinx_dma_free_descriptors(chan);
>> +	chan->idle = true;
>>
>>  	if (chan->cyclic) {
>>  		reg = dma_ctrl_read(chan, XILINX_DMA_REG_DMACR); @@ -
>2344,6
>> +2322,12 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device
>*xdev,
>>  	chan->has_sg = xdev->has_sg;
>>  	chan->desc_pendingcount = 0x0;
>>  	chan->ext_addr = xdev->ext_addr;
>> +	/* This variable enusres that descripotrs are not
>				      ^^^^^^^^^^
>
>typo

Since this patch got applied 
Will take care of this next time on wards... 
Thanks for the review... 

Regards,
Kedar.

>
>--
>~Vinod