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@xxxxxxxxxxxx>
Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
---
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
--
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