linux-kernel - [PATCH 3.19.y-ckt 105/210] dmaengine: dw: fix cyclic transfer setup

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Message-Id: <1454030348-17736-106-git-send-email-kamal@canonical.com>
Date:	Thu, 28 Jan 2016 17:17:23 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Mans Rullgard <mans@...sr.com>, Vinod Koul <vinod.koul@...el.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 105/210] dmaengine: dw: fix cyclic transfer setup

3.19.8-ckt14 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mans Rullgard <mans@...sr.com>

commit df3bb8a0e619d501cd13334c3e0586edcdcbc716 upstream.

Commit 61e183f83069 ("dmaengine/dw_dmac: Reconfigure interrupt and
chan_cfg register on resume") moved some channel initialisation to
a new function which must be called before starting a transfer.

This updates dw_dma_cyclic_start() to use dwc_dostart() like the other
modes, thus ensuring dwc_initialize() gets called and removing some code
duplication.

Fixes: 61e183f83069 ("dmaengine/dw_dmac: Reconfigure interrupt and chan_cfg register on resume")
Signed-off-by: Mans Rullgard <mans@...sr.com>
Reviewed-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Vinod Koul <vinod.koul@...el.com>
[ kamal: backport to 3.19-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/dma/dw/core.c | 22 +---------------------
 1 file changed, 1 insertion(+), 21 deletions(-)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 1383c73..c90f63b 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1238,7 +1238,6 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
 int dw_dma_cyclic_start(struct dma_chan *chan)
 {
 	struct dw_dma_chan	*dwc = to_dw_dma_chan(chan);
-	struct dw_dma		*dw = to_dw_dma(dwc->chan.device);
 	unsigned long		flags;
 
 	if (!test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) {
@@ -1247,26 +1246,7 @@ int dw_dma_cyclic_start(struct dma_chan *chan)
 	}
 
 	spin_lock_irqsave(&dwc->lock, flags);
-
-	/* Assert channel is idle */
-	if (dma_readl(dw, CH_EN) & dwc->mask) {
-		dev_err(chan2dev(&dwc->chan),
-			"BUG: Attempted to start non-idle channel\n");
-		dwc_dump_chan_regs(dwc);
-		spin_unlock_irqrestore(&dwc->lock, flags);
-		return -EBUSY;
-	}
-
-	dma_writel(dw, CLEAR.ERROR, dwc->mask);
-	dma_writel(dw, CLEAR.XFER, dwc->mask);
-
-	/* Setup DMAC channel registers */
-	channel_writel(dwc, LLP, dwc->cdesc->desc[0]->txd.phys);
-	channel_writel(dwc, CTL_LO, DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN);
-	channel_writel(dwc, CTL_HI, 0);
-
-	channel_set_bit(dw, CH_EN, dwc->mask);
-
+	dwc_dostart(dwc, dwc->cdesc->desc[0]);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;
-- 
1.9.1