[alsa-devel] [PATCH 2/2] OMAP2+: DMA: Workaround for invalid destination position

[Peter Ujfalusi]

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 at ti.com>
---
 arch/arm/plat-omap/dma.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index 38b0d44..9186491 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -1066,8 +1066,16 @@ dma_addr_t omap_get_dma_dst_pos(int lch)
 
 	if (cpu_is_omap15xx())
 		offset = p->dma_read(CPC, lch);
-	else
+	else {
 		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);
+	}
 
 	/*
 	 * omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
-- 
1.7.7.1