Add a spinlock and an 'enabled' boolean on channel descriptor, to avoid
using buffer descriptors in the interrupt context,
when sdma_disable_channel is called meanwhile.
Signed-off-by: Thierry Bultel <tbultel@xxxxxxxxxxxxxxx>
---
Changes since V1:
* Applied Shunyong Yang's review advice:
* Use a bool type for the enabled field
* Fixed the race condition
drivers/dma/imx-sdma.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index d1651a5..0df6d54 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -330,6 +330,7 @@ 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)
@@ -588,7 +589,13 @@ static int sdma_config_ownership(struct sdma_channel *sdmac,
static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
{
+ unsigned long flags;
+ struct sdma_channel *sdmac = &sdma->channel[channel];
writel(BIT(channel), sdma->regs + SDMA_H_START);
+
+ spin_lock_irqsave(&sdmac->lock, flags);
+ sdmac->enabled = 1;
+ spin_unlock_irqrestore(&sdmac->lock, flags);
}
/*
@@ -677,6 +684,14 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac)
struct sdma_buffer_descriptor *bd;
int error = 0;
enum dma_status old_status = sdmac->status;
+ unsigned long flags;
+
+ spin_lock_irqsave(&sdmac->lock, flags);
+ if (!sdmac->enabled) {
+ spin_unlock_irqrestore(&sdmac->lock, flags);
+ return;
+ }
+ spin_unlock_irqrestore(&sdmac->lock, flags);
/*
* loop mode. Iterate over descriptors, re-setup them and
@@ -930,10 +945,15 @@ 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;
writel_relaxed(BIT(channel), sdma->regs + SDMA_H_STATSTOP);
sdmac->status = DMA_ERROR;
+ spin_lock_irqsave(&sdmac->lock, flags);
+ sdmac->enabled = 0;
+ spin_unlock_irqrestore(&sdmac->lock, flags);
+
return 0;
}
--
2.7.4
--
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