This patch adds dma_pause operation. This patch is based on
Muhammad Hamza Farooq's patch.
After this patch applied, an issue that the sh-sci driver with
high baud rate might cause data lost disappeared because the DMAC
is possible to transmit between [1] and [2] below, and then
the residue of [1] is not true:
In rx_timer_fn() of the sh-sci.c:
dmaengine_pause();
...
dmaengine_tx_status(); /* [1] */
...
dmaengine_terminate_all() /* [2] */
Signed-off-by: Yoshihiro Shimoda <[email protected]>
---
drivers/dma/sh/rcar-dmac.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index afd8c7b..285967b 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -836,6 +836,17 @@ static void rcar_dmac_stop_all_chan(struct rcar_dmac *dmac)
}
}
+static int rcar_dmac_chan_pause(struct dma_chan *chan)
+{
+ unsigned long flags;
+ struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
+
+ spin_lock_irqsave(&rchan->lock, flags);
+ rcar_dmac_clear_chcr_de(rchan);
+ spin_unlock_irqrestore(&rchan->lock, flags);
+
+ return 0;
+}
/*
-----------------------------------------------------------------------------
* Descriptors preparation
@@ -1858,6 +1869,7 @@ static int rcar_dmac_probe(struct platform_device *pdev)
engine->device_prep_slave_sg = rcar_dmac_prep_slave_sg;
engine->device_prep_dma_cyclic = rcar_dmac_prep_dma_cyclic;
engine->device_config = rcar_dmac_device_config;
+ engine->device_pause = rcar_dmac_chan_pause;
engine->device_terminate_all = rcar_dmac_chan_terminate_all;
engine->device_tx_status = rcar_dmac_tx_status;
engine->device_issue_pending = rcar_dmac_issue_pending;
--
1.9.1
