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

[Kedareswara rao Appana]

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

Signed-off-by: Kedareswara rao Appana <appa...@xilinx.com>
---
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