ARM: OMAP2+: DMA: Workaround for invalid destination position

If the DMA destination position has been asked before the
first actual data transfer has been done, the CDAC
register still contains 0 (it is initialized to 0 at
omsp_dma_start).
If CDAC == 0, return the programmed start address.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index a9983b695a18..002fb4d96bbc 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -1074,8 +1074,16 @@ dma_addr_t omap_get_dma_dst_pos(int lch)
          * omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
          * read before the DMA controller finished disabling the channel.
          */
-        if (!cpu_is_omap15xx() && offset == 0)
+        if (!cpu_is_omap15xx() && offset == 0) {
                 offset = p->dma_read(CDAC, lch);
+                /*
+                 * CDAC == 0 indicates that the DMA transfer on the channel has
+                 * not been started (no data has been transferred so far).
+                 * Return the programmed destination start address in this case.
+                 */
+                if (unlikely(!offset))
+                        offset = p->dma_read(CDSA, lch);
+        }
 
         if (cpu_class_is_omap1())
                 offset |= (p->dma_read(CDSA, lch) & 0xFFFF0000);