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[PATCH 05/10] dma: imx-sdma: add flag to indicate SDMA channel state

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There is race between STOP of SDMA channel and finish of
SDMA transfer, so some times, even after sdma_disable_channel()
is called, the bit of 'terminated channel' in INTR may still get
asserted, thus cause an extra sdma tasklet be called.
Add flag 'enabled' to each sdma channel to indicate its state.
only when SDMA channel is in its enabled state, irq handler
can schedule a sdma tasklet for it.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
 drivers/dma/imx-sdma.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 36f5e39..ef5d37c 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -327,6 +327,7 @@ struct sdma_channel {
 	unsigned int			chn_real_count;
 	struct tasklet_struct		tasklet;
 	struct imx_dma_data		data;
+	bool				enabled;
 };
 
 #define IMX_DMA_SG_LOOP		BIT(0)
@@ -562,7 +563,13 @@ static int sdma_config_ownership(struct sdma_channel *sdmac,
 
 static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
 {
+	struct sdma_channel *sdmac = &sdma->channel[channel];
+	unsigned long flags;
+
+	spin_lock_irqsave(&sdmac->lock, flags);
+	sdmac->enabled = true;
 	writel(BIT(channel), sdma->regs + SDMA_H_START);
+	spin_unlock_irqrestore(&sdmac->lock, flags);
 }
 
 /*
@@ -740,9 +747,12 @@ static irqreturn_t sdma_int_handler(int irq, void *dev_id)
 		int channel = fls(stat) - 1;
 		struct sdma_channel *sdmac = &sdma->channel[channel];
 
-		tasklet_schedule(&sdmac->tasklet);
+		spin_lock(&sdmac->lock);
+		if (sdmac->enabled)
+			tasklet_schedule(&sdmac->tasklet);
 
 		__clear_bit(channel, &stat);
+		spin_unlock(&sdmac->lock);
 	}
 
 	return IRQ_HANDLED;
@@ -906,9 +916,13 @@ static int sdma_disable_channel(struct dma_chan *chan)
 	struct sdma_channel *sdmac = to_sdma_chan(chan);
 	struct sdma_engine *sdma = sdmac->sdma;
 	int channel = sdmac->channel;
+	unsigned long flags;
 
+	spin_lock_irqsave(&sdmac->lock, flags);
+	sdmac->enabled = false;
 	writel_relaxed(BIT(channel), sdma->regs + SDMA_H_STATSTOP);
 	sdmac->status = DMA_ERROR;
+	spin_unlock_irqrestore(&sdmac->lock, flags);
 
 	return 0;
 }
-- 
2.4.5

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[PATCH v1 00/10] *** imx-sdma: misc fix *** Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 06/10] dma: imx-sdma: add terminate_all support Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 02/10] dma: imx-sdma: don't update BD in isr routine Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 08/10] dma: imx-sdma: abort updating channel when it has been terminated Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 10/10] dma: imx-sdma: clear channel0 interrupt bit in irq routine Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 07/10] dma: imx-sdma: Add synchronization support Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:40 +0200
  [PATCH 01/10] dma: imx-sdma: use chn_real_count to report residue for UART Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:50 +0200
  [PATCH 05/10] dma: imx-sdma: add flag to indicate SDMA channel state Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:50 +0200
  [PATCH 03/10] dma: imx-sdma: clear BD_RROR flag before pass it to sdma script Jiada Wang <jiada_wang@mentor.com> - 2016-05-16 10:50 +0200
  Re: [PATCH v1 00/10] *** imx-sdma: misc fix *** Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> - 2016-05-16 13:10 +0200

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