Hi Kedareswara,
Thank you for the patch.
On Thursday 15 Dec 2016 20:41:20 Kedareswara rao Appana wrote:
> Add channel idle state to ensure that dma descriptor is not
> submitted when VDMA engine is in progress.
>
> Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
> ---
> drivers/dma/xilinx/xilinx_dma.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/dma/xilinx/xilinx_dma.c
> b/drivers/dma/xilinx/xilinx_dma.c index 8288fe4..736c2a3 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
> @@ -351,6 +352,7 @@ 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;
> @@ -966,6 +968,7 @@ static void xilinx_dma_halt(struct xilinx_dma_chan
> *chan) chan, dma_ctrl_read(chan, XILINX_DMA_REG_DMASR));
> chan->err = true;
> }
> + chan->idle = true;
> }
>
> /**
> @@ -1007,6 +1010,9 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_dma_chan *chan)
> if (chan->err)
> return;
>
> + if (!chan->idle)
> + return;
Don't you need to perform the same check for the DMA and CDMA channels ? If
so, shouldn't this be moved to common code ?
There's another problem (not strictly introduced by this patch) I wanted to
mention. The append_desc_queue() function, called from your tx_submit handler,
appends descriptors to the pending_list. The DMA engine API states that a
transfer submitted by tx_submit will not be executed until .issue_pending() is
called. However, if a transfer is in progress at tx_submit time, I believe
that the IRQ handler, at transfer completion, will start the next transfer
from the pending_list even if .issue_pending() hasn't been called for it.
> if (list_empty(&chan->pending_list))
> return;
Now that you catch busy channels with a software flag, do you still need the
xilinx_dma_is_running() and xilinx_dma_is_idle() checks ? Three different
checks for the same or very similar conditions are confusing, if you really
need them you should document clearly how they differ.
> @@ -1110,6 +1116,7 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_dma_chan *chan) vdma_desc_write(chan, XILINX_DMA_REG_VSIZE,
> last->hw.vsize);
> }
>
> + chan->idle = false;
(and this too)
> if (!chan->has_sg) {
> list_del(&desc->node);
> list_add_tail(&desc->node, &chan->active_list);
> @@ -1447,6 +1454,7 @@ 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);
> }
> @@ -2327,6 +2335,7 @@ 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;
> + chan->idle = true;
>
> spin_lock_init(&chan->lock);
> INIT_LIST_HEAD(&chan->pending_list);
--
Regards,
Laurent Pinchart
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