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dmaengine: sh: rcar-dmac: Add dma_pause operation 

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 <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Yoshihiro Shimoda 2018-07-11 11:10:16 +09:00 committed by Vinod Koul
parent 4de1247a98
commit 8115ce745f
1 changed files with 12 additions and 0 deletions
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12
drivers/dma/sh/rcar-dmac.c
View File

@ -834,6 +834,17 @@ 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
@ -1864,6 +1875,7 @@ 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;