ARM: OMAP: Fix race in OMAP2/3 DMA IRQ handling

CSR must be cleared before invoking the callback.

If the callback function starts a new, fast DMA transfer on the same
channel, the completion status might lost if CSR is cleared after
the callback invocation.

Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index 6ccafbc..ee77013 100755 (executable)
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -1913,11 +1913,11 @@ static int omap2_dma_handle_ch(int ch)
                status = dma_read(CSR(ch));
        }
 
+       dma_write(status, CSR(ch));
+
        if (likely(dma_chan[ch].callback != NULL))
                dma_chan[ch].callback(ch, status, dma_chan[ch].data);
 
-       dma_write(status, CSR(ch));
-
        return 0;
 }