omap: Fix race condition in omap dma driver
The bug could cause irq enable bit of one DMA channel is cleared/set unexpectedly when 2 (or more) drivers are calling omap_request_dma()/omap_free_dma() simultaneously Signed-off-by: Fei Yang <AFY095@motorola.com> Signed-off-by: Tao Hu <taohu@motorola.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
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@ -691,13 +691,16 @@ static inline void disable_lnk(int lch)
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static inline void omap2_enable_irq_lch(int lch)
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{
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u32 val;
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unsigned long flags;
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if (!cpu_class_is_omap2())
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return;
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spin_lock_irqsave(&dma_chan_lock, flags);
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val = dma_read(IRQENABLE_L0);
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val |= 1 << lch;
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dma_write(val, IRQENABLE_L0);
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spin_unlock_irqrestore(&dma_chan_lock, flags);
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}
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int omap_request_dma(int dev_id, const char *dev_name,
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@ -799,10 +802,13 @@ void omap_free_dma(int lch)
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if (cpu_class_is_omap2()) {
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u32 val;
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spin_lock_irqsave(&dma_chan_lock, flags);
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/* Disable interrupts */
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val = dma_read(IRQENABLE_L0);
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val &= ~(1 << lch);
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dma_write(val, IRQENABLE_L0);
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spin_unlock_irqrestore(&dma_chan_lock, flags);
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/* Clear the CSR register and IRQ status register */
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dma_write(OMAP2_DMA_CSR_CLEAR_MASK, CSR(lch));
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