[PATCH v2 4/4] dmaengine: xilinx_vdma: Improve channel idle checking

From: Kedareswara rao Appana
Date: Mon Feb 22 2016 - 00:55:05 EST


This patch improves the channel idle cheking by introduing
a new varibale in chan private structure.

Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
---
Changes for v2:
---> splitted the changes into multiple patches.

drivers/dma/xilinx/xilinx_vdma.c | 41 ++++++++--------------------------------
1 file changed, 8 insertions(+), 33 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_vdma.c b/drivers/dma/xilinx/xilinx_vdma.c
index 8db07f7..51686d1 100644
--- a/drivers/dma/xilinx/xilinx_vdma.c
+++ b/drivers/dma/xilinx/xilinx_vdma.c
@@ -202,6 +202,7 @@ struct xilinx_vdma_tx_descriptor {
* @has_sg: Support scatter 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
@@ -225,6 +226,7 @@ struct xilinx_vdma_chan {
bool has_sg;
bool genlock;
bool err;
+ bool idle;
struct tasklet_struct tasklet;
struct xilinx_vdma_config config;
bool flush_on_fsync;
@@ -519,32 +521,6 @@ static enum dma_status xilinx_vdma_tx_status(struct dma_chan *dchan,
}

/**
- * xilinx_vdma_is_running - Check if VDMA channel is running
- * @chan: Driver specific VDMA channel
- *
- * Return: '1' if running, '0' if not.
- */
-static bool xilinx_vdma_is_running(struct xilinx_vdma_chan *chan)
-{
- return !(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
- XILINX_VDMA_DMASR_HALTED) &&
- (vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR) &
- XILINX_VDMA_DMACR_RUNSTOP);
-}
-
-/**
- * xilinx_vdma_is_idle - Check if VDMA channel is idle
- * @chan: Driver specific VDMA channel
- *
- * Return: '1' if idle, '0' if not.
- */
-static bool xilinx_vdma_is_idle(struct xilinx_vdma_chan *chan)
-{
- return vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
- XILINX_VDMA_DMASR_IDLE;
-}
-
-/**
* xilinx_vdma_halt - Halt VDMA channel
* @chan: Driver specific VDMA channel
*/
@@ -614,6 +590,9 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
if (list_empty(&chan->pending_list))
return;

+ if (!chan->idle)
+ return;
+
desc = list_first_entry(&chan->pending_list,
struct xilinx_vdma_tx_descriptor, node);
tail_desc = list_last_entry(&chan->pending_list,
@@ -622,13 +601,6 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_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_vdma_is_running(chan) &&
- !xilinx_vdma_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
@@ -708,6 +680,7 @@ static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)

list_splice_tail_init(&chan->pending_list, &chan->active_list);
chan->desc_pendingcount = 0;
+ chan->idle = false;
}

/**
@@ -854,6 +827,7 @@ static irqreturn_t xilinx_vdma_irq_handler(int irq, void *data)
if (status & XILINX_VDMA_DMASR_FRM_CNT_IRQ) {
spin_lock(&chan->lock);
xilinx_vdma_complete_descriptor(chan);
+ chan->idle = true;
xilinx_vdma_start_transfer(chan);
spin_unlock(&chan->lock);
}
@@ -1212,6 +1186,7 @@ static int xilinx_vdma_chan_probe(struct xilinx_vdma_device *xdev,

list_add_tail(&chan->common.device_node, &xdev->common.channels);
xdev->chan[chan->id] = chan;
+ chan->idle = true;

/* Reset the channel */
err = xilinx_vdma_chan_reset(chan);
--
2.1.2