[PATCH v2 1/4] dmaengine: xilinx_vdma: Improve SG engine handling
Kedareswara rao Appana
appana.durga.rao at xilinx.com
Sun Feb 21 21:54:34 PST 2016
The current driver allows user to queue up multiple segments
on to a single transaction descriptor. User will submit this single desc
and in the issue_pending() we decode multiple segments and submit to SG HW engine.
We free up the allocated_desc when it is submitted to the HW.
Existing code prevents the user to prepare multiple trasactions at same time as
we are overwrite with the allocated_desc.
The best utilization of HW SG engine would happen if we collate the pending
list when we start dma this patch updates the same.
Signed-off-by: Kedareswara rao Appana <appanad at xilinx.com>
---
Changes for v2:
---> splitted the changes into multiple patches.
drivers/dma/xilinx/xilinx_vdma.c | 127 ++++++++++++++++++++++-----------------
1 file changed, 72 insertions(+), 55 deletions(-)
diff --git a/drivers/dma/xilinx/xilinx_vdma.c b/drivers/dma/xilinx/xilinx_vdma.c
index 6f4b501..06bffec 100644
--- a/drivers/dma/xilinx/xilinx_vdma.c
+++ b/drivers/dma/xilinx/xilinx_vdma.c
@@ -190,8 +190,7 @@ struct xilinx_vdma_tx_descriptor {
* @desc_offset: TX descriptor registers offset
* @lock: Descriptor operation lock
* @pending_list: Descriptors waiting
- * @active_desc: Active descriptor
- * @allocated_desc: Allocated descriptor
+ * @active_list: Descriptors ready to submit
* @done_list: Complete descriptors
* @common: DMA common channel
* @desc_pool: Descriptors pool
@@ -206,6 +205,7 @@ struct xilinx_vdma_tx_descriptor {
* @tasklet: Cleanup work after irq
* @config: Device configuration info
* @flush_on_fsync: Flush on Frame sync
+ * @desc_pendingcount: Descriptor pending count
*/
struct xilinx_vdma_chan {
struct xilinx_vdma_device *xdev;
@@ -213,8 +213,7 @@ struct xilinx_vdma_chan {
u32 desc_offset;
spinlock_t lock;
struct list_head pending_list;
- struct xilinx_vdma_tx_descriptor *active_desc;
- struct xilinx_vdma_tx_descriptor *allocated_desc;
+ struct list_head active_list;
struct list_head done_list;
struct dma_chan common;
struct dma_pool *desc_pool;
@@ -229,6 +228,7 @@ struct xilinx_vdma_chan {
struct tasklet_struct tasklet;
struct xilinx_vdma_config config;
bool flush_on_fsync;
+ u32 desc_pendingcount;
};
/**
@@ -342,19 +342,11 @@ static struct xilinx_vdma_tx_descriptor *
xilinx_vdma_alloc_tx_descriptor(struct xilinx_vdma_chan *chan)
{
struct xilinx_vdma_tx_descriptor *desc;
- unsigned long flags;
-
- if (chan->allocated_desc)
- return chan->allocated_desc;
desc = kzalloc(sizeof(*desc), GFP_KERNEL);
if (!desc)
return NULL;
- spin_lock_irqsave(&chan->lock, flags);
- chan->allocated_desc = desc;
- spin_unlock_irqrestore(&chan->lock, flags);
-
INIT_LIST_HEAD(&desc->segments);
return desc;
@@ -412,9 +404,7 @@ static void xilinx_vdma_free_descriptors(struct xilinx_vdma_chan *chan)
xilinx_vdma_free_desc_list(chan, &chan->pending_list);
xilinx_vdma_free_desc_list(chan, &chan->done_list);
-
- xilinx_vdma_free_tx_descriptor(chan, chan->active_desc);
- chan->active_desc = NULL;
+ xilinx_vdma_free_desc_list(chan, &chan->active_list);
spin_unlock_irqrestore(&chan->lock, flags);
}
@@ -614,25 +604,26 @@ static void xilinx_vdma_start(struct xilinx_vdma_chan *chan)
static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
{
struct xilinx_vdma_config *config = &chan->config;
- struct xilinx_vdma_tx_descriptor *desc;
+ struct xilinx_vdma_tx_descriptor *desc, *tail_desc;
unsigned long flags;
u32 reg;
- struct xilinx_vdma_tx_segment *head, *tail = NULL;
+ struct xilinx_vdma_tx_segment *tail_segment;
if (chan->err)
return;
spin_lock_irqsave(&chan->lock, flags);
- /* There's already an active descriptor, bail out. */
- if (chan->active_desc)
- goto out_unlock;
-
if (list_empty(&chan->pending_list))
goto out_unlock;
desc = list_first_entry(&chan->pending_list,
struct xilinx_vdma_tx_descriptor, node);
+ tail_desc = list_last_entry(&chan->pending_list,
+ struct xilinx_vdma_tx_descriptor, node);
+
+ 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_vdma_is_running(chan) &&
@@ -645,14 +636,9 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
* If hardware is idle, then all descriptors on the running lists are
* done, start new transfers
*/
- if (chan->has_sg) {
- head = list_first_entry(&desc->segments,
- struct xilinx_vdma_tx_segment, node);
- tail = list_entry(desc->segments.prev,
- struct xilinx_vdma_tx_segment, node);
-
- vdma_ctrl_write(chan, XILINX_VDMA_REG_CURDESC, head->phys);
- }
+ if (chan->has_sg)
+ vdma_ctrl_write(chan, XILINX_VDMA_REG_CURDESC,
+ desc->async_tx.phys);
/* Configure the hardware using info in the config structure */
reg = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR);
@@ -694,12 +680,15 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
/* Start the transfer */
if (chan->has_sg) {
- vdma_ctrl_write(chan, XILINX_VDMA_REG_TAILDESC, tail->phys);
+ vdma_ctrl_write(chan, XILINX_VDMA_REG_TAILDESC,
+ tail_segment->phys);
} else {
struct xilinx_vdma_tx_segment *segment, *last = NULL;
int i = 0;
- list_for_each_entry(segment, &desc->segments, node) {
+ list_for_each_entry(desc, &chan->pending_list, node) {
+ segment = list_first_entry(&desc->segments,
+ struct xilinx_vdma_tx_segment, node);
vdma_desc_write(chan,
XILINX_VDMA_REG_START_ADDRESS(i++),
segment->hw.buf_addr);
@@ -716,8 +705,8 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
vdma_desc_write(chan, XILINX_VDMA_REG_VSIZE, last->hw.vsize);
}
- list_del(&desc->node);
- chan->active_desc = desc;
+ list_splice_tail_init(&chan->pending_list, &chan->active_list);
+ chan->desc_pendingcount = 0;
out_unlock:
spin_unlock_irqrestore(&chan->lock, flags);
@@ -742,21 +731,19 @@ static void xilinx_vdma_issue_pending(struct dma_chan *dchan)
*/
static void xilinx_vdma_complete_descriptor(struct xilinx_vdma_chan *chan)
{
- struct xilinx_vdma_tx_descriptor *desc;
+ struct xilinx_vdma_tx_descriptor *desc, *next;
unsigned long flags;
spin_lock_irqsave(&chan->lock, flags);
- desc = chan->active_desc;
- if (!desc) {
- dev_dbg(chan->dev, "no running descriptors\n");
+ if (list_empty(&chan->active_list))
goto out_unlock;
- }
-
- dma_cookie_complete(&desc->async_tx);
- list_add_tail(&desc->node, &chan->done_list);
- chan->active_desc = NULL;
+ list_for_each_entry_safe(desc, next, &chan->active_list, node) {
+ list_del(&desc->node);
+ dma_cookie_complete(&desc->async_tx);
+ list_add_tail(&desc->node, &chan->done_list);
+ }
out_unlock:
spin_unlock_irqrestore(&chan->lock, flags);
@@ -879,6 +866,44 @@ static irqreturn_t xilinx_vdma_irq_handler(int irq, void *data)
}
/**
+ * append_desc_queue - Queuing descriptor
+ * @chan: Driver specific dma channel
+ * @desc: dma transaction descriptor
+ */
+static void append_desc_queue(struct xilinx_vdma_chan *chan,
+ struct xilinx_vdma_tx_descriptor *desc)
+{
+ struct xilinx_vdma_tx_segment *tail_segment;
+ struct xilinx_vdma_tx_descriptor *tail_desc;
+
+ if (list_empty(&chan->pending_list))
+ goto append;
+
+ /*
+ * Add the hardware descriptor to the chain of hardware descriptors
+ * that already exists in memory.
+ */
+ tail_desc = list_last_entry(&chan->pending_list,
+ struct xilinx_vdma_tx_descriptor, node);
+ tail_segment = list_last_entry(&tail_desc->segments,
+ struct xilinx_vdma_tx_segment, node);
+ tail_segment->hw.next_desc = (u32)desc->async_tx.phys;
+
+ /*
+ * Add the software descriptor and all children to the list
+ * of pending transactions
+ */
+append:
+ list_add_tail(&desc->node, &chan->pending_list);
+ chan->desc_pendingcount++;
+
+ if (unlikely(chan->desc_pendingcount > chan->num_frms)) {
+ dev_dbg(chan->dev, "desc pendingcount is too high\n");
+ chan->desc_pendingcount = chan->num_frms;
+ }
+}
+
+/**
* xilinx_vdma_tx_submit - Submit DMA transaction
* @tx: Async transaction descriptor
*
@@ -906,11 +931,8 @@ static dma_cookie_t xilinx_vdma_tx_submit(struct dma_async_tx_descriptor *tx)
cookie = dma_cookie_assign(tx);
- /* Append the transaction to the pending transactions queue. */
- list_add_tail(&desc->node, &chan->pending_list);
-
- /* Free the allocated desc */
- chan->allocated_desc = NULL;
+ /* Put this transaction onto the tail of the pending queue */
+ append_desc_queue(chan, desc);
spin_unlock_irqrestore(&chan->lock, flags);
@@ -973,13 +995,6 @@ xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
else
hw->buf_addr = xt->src_start;
- /* Link the previous next descriptor to current */
- if (!list_empty(&desc->segments)) {
- prev = list_last_entry(&desc->segments,
- struct xilinx_vdma_tx_segment, node);
- prev->hw.next_desc = segment->phys;
- }
-
/* Insert the segment into the descriptor segments list. */
list_add_tail(&segment->node, &desc->segments);
@@ -988,7 +1003,7 @@ xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
/* Link the last hardware descriptor with the first. */
segment = list_first_entry(&desc->segments,
struct xilinx_vdma_tx_segment, node);
- prev->hw.next_desc = segment->phys;
+ desc->async_tx.phys = segment->phys;
return &desc->async_tx;
@@ -1127,10 +1142,12 @@ static int xilinx_vdma_chan_probe(struct xilinx_vdma_device *xdev,
chan->dev = xdev->dev;
chan->xdev = xdev;
chan->has_sg = xdev->has_sg;
+ chan->desc_pendingcount = 0x0;
spin_lock_init(&chan->lock);
INIT_LIST_HEAD(&chan->pending_list);
INIT_LIST_HEAD(&chan->done_list);
+ INIT_LIST_HEAD(&chan->active_list);
/* Retrieve the channel properties from the device tree */
has_dre = of_property_read_bool(node, "xlnx,include-dre");
--
2.1.2
More information about the linux-arm-kernel
mailing list