[PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

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[PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

Joel Fernandes
The vchan lock in edma_callback is acquired in hard interrupt context. As
interrupts are already disabled, there's no point in save/restoring interrupt
mask bit or cpsr flags.

Get rid of flags local variable and use spin_lock instead of spin_lock_irqsave.

Signed-off-by: Joel Fernandes <[hidden email]>
---
 drivers/dma/edma.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 91849aa..25a75e2 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -638,7 +638,6 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
  struct edma_chan *echan = data;
  struct device *dev = echan->vchan.chan.device->dev;
  struct edma_desc *edesc;
- unsigned long flags;
  struct edmacc_param p;
 
  edesc = echan->edesc;
@@ -649,7 +648,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 
  switch (ch_status) {
  case EDMA_DMA_COMPLETE:
- spin_lock_irqsave(&echan->vchan.lock, flags);
+ spin_lock(&echan->vchan.lock);
 
  if (edesc) {
  if (edesc->cyclic) {
@@ -665,11 +664,11 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
  }
  }
 
- spin_unlock_irqrestore(&echan->vchan.lock, flags);
+ spin_unlock(&echan->vchan.lock);
 
  break;
  case EDMA_DMA_CC_ERROR:
- spin_lock_irqsave(&echan->vchan.lock, flags);
+ spin_lock(&echan->vchan.lock);
 
  edma_read_slot(EDMA_CHAN_SLOT(echan->slot[0]), &p);
 
@@ -700,7 +699,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
  edma_trigger_channel(echan->ch_num);
  }
 
- spin_unlock_irqrestore(&echan->vchan.lock, flags);
+ spin_unlock(&echan->vchan.lock);
 
  break;
  default:
--
1.7.9.5

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Re: [PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

Vinod Koul-3
On Thu, Apr 17, 2014 at 12:58:33AM -0500, Joel Fernandes wrote:
> The vchan lock in edma_callback is acquired in hard interrupt context. As
> interrupts are already disabled, there's no point in save/restoring interrupt
> mask bit or cpsr flags.
>
> Get rid of flags local variable and use spin_lock instead of spin_lock_irqsave.

Applied, thanks

--
~Vinod

>
> Signed-off-by: Joel Fernandes <[hidden email]>
> ---
>  drivers/dma/edma.c |    9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
> index 91849aa..25a75e2 100644
> --- a/drivers/dma/edma.c
> +++ b/drivers/dma/edma.c
> @@ -638,7 +638,6 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>   struct edma_chan *echan = data;
>   struct device *dev = echan->vchan.chan.device->dev;
>   struct edma_desc *edesc;
> - unsigned long flags;
>   struct edmacc_param p;
>  
>   edesc = echan->edesc;
> @@ -649,7 +648,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>  
>   switch (ch_status) {
>   case EDMA_DMA_COMPLETE:
> - spin_lock_irqsave(&echan->vchan.lock, flags);
> + spin_lock(&echan->vchan.lock);
>  
>   if (edesc) {
>   if (edesc->cyclic) {
> @@ -665,11 +664,11 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>   }
>   }
>  
> - spin_unlock_irqrestore(&echan->vchan.lock, flags);
> + spin_unlock(&echan->vchan.lock);
>  
>   break;
>   case EDMA_DMA_CC_ERROR:
> - spin_lock_irqsave(&echan->vchan.lock, flags);
> + spin_lock(&echan->vchan.lock);
>  
>   edma_read_slot(EDMA_CHAN_SLOT(echan->slot[0]), &p);
>  
> @@ -700,7 +699,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>   edma_trigger_channel(echan->ch_num);
>   }
>  
> - spin_unlock_irqrestore(&echan->vchan.lock, flags);
> + spin_unlock(&echan->vchan.lock);
>  
>   break;
>   default:
> --
> 1.7.9.5
>

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