Blackfin: add SSYNC to set_dma_sg() for descriptor fetching

Make sure the internal core buffers are flushed before telling the DMA
engine to fetch the descriptor structure so that it gets the right values.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/blackfin/include/asm/dma.h b/arch/blackfin/include/asm/dma.h
index 46c56185417a..c9a59622e23f 100644
--- a/arch/blackfin/include/asm/dma.h
+++ b/arch/blackfin/include/asm/dma.h
@@ -206,10 +206,16 @@ static inline unsigned long get_dma_curr_addr(unsigned int channel)
 
 static inline void set_dma_sg(unsigned int channel, struct dmasg *sg, int ndsize)
 {
+        /* Make sure the internal data buffers in the core are drained
+         * so that the DMA descriptors are completely written when the
+         * DMA engine goes to fetch them below.
+         */
+        SSYNC();
+
+        dma_ch[channel].regs->next_desc_ptr = sg;
         dma_ch[channel].regs->cfg =
                 (dma_ch[channel].regs->cfg & ~(0xf << 8)) |
                 ((ndsize & 0xf) << 8);
-        dma_ch[channel].regs->next_desc_ptr = sg;
 }
 
 static inline int dma_channel_active(unsigned int channel)