Gitweb: http://git.kernel.org/linus/bb17ef102b72e38557bfa829511e06c4bd3bb972
Commit: bb17ef102b72e38557bfa829511e06c4bd3bb972
Parent: 5eb2e891f038c8e04757f4536b9693faf35978a3
Author: Brian Niebuhr <bniebuhr3@gmail.com>
AuthorDate: Tue Mar 9 16:48:03 2010 -0600
Committer: Kevin Hilman <khilman@deeprootsystems.com>
CommitDate: Mon Apr 5 15:25:11 2010 -0700
davinci: edma: clear events in edma_start()
This patch fixes an issue where a DMA channel can erroneously process an
event generated by a previous transfer. A failure case is where DMA is
being used for SPI transmit and receive channels on OMAP L138. In this
case there is a single bit that controls all event generation from the
SPI peripheral. Therefore it is possible that between when edma_stop()
has been called for the transmit channel on a previous transfer and
edma_start() is called for the transmit channel on a subsequent transfer,
that a transmit event has been generated.
The fix is to clear events in edma_start(). This prevents false events
from being processed when events are enabled for that channel.
Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
arch/arm/mach-davinci/dma.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-davinci/dma.c b/arch/arm/mach-davinci/dma.c
index 15dd886..260485c 100644
--- a/arch/arm/mach-davinci/dma.c
+++ b/arch/arm/mach-davinci/dma.c
@@ -1266,7 +1266,8 @@ int edma_start(unsigned channel)
/* EDMA channel with event association */
pr_debug("EDMA: ER%d %08x\n", j,
edma_shadow0_read_array(ctlr, SH_ER, j));
- /* Clear any pending error */
+ /* Clear any pending event or error */
+ edma_write_array(ctlr, EDMA_ECR, j, mask);
edma_write_array(ctlr, EDMA_EMCR, j, mask);
/* Clear any SER */
edma_shadow0_write_array(ctlr, SH_SECR, j, mask);
--
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