linux-kernel - [PATCH AUTOSEL for 4.9 196/293] dmaengine: qcom

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Date:   Mon, 9 Apr 2018 00:25:27 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Sinan Kaya <okaya@...eaurora.org>,
        Vinod Koul <vinod.koul@...el.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 196/293] dmaengine: qcom_hidma: correct API
 violation for submit

From: Sinan Kaya <okaya@...eaurora.org>

[ Upstream commit 99efdb3e48fb2fa84addb3102946d3eca341192b ]

Current code is violating the DMA Engine API by putting the submitted
requests directly into the HW queue. This causes queued transactions
to be started by another thread as soon as the first one finishes.

The DMA Engine document clearly states this.

"dmaengine_submit() will not start the DMA operation".

Move HW queuing of the requests into the issue_pending() routine
to comply with API requirements also create a new queued state for
temporarily holding the requests.

A descriptor goes through these transitions now.

free->prepared->queued->active->completed->free

as opposed to

free->prepared->active->completed->free

Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@...el.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/dma/qcom/hidma.c | 15 ++++++++++++---
 drivers/dma/qcom/hidma.h |  1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
index e244e10a94b5..d38a2ceaa0dc 100644
--- a/drivers/dma/qcom/hidma.c
+++ b/drivers/dma/qcom/hidma.c
@@ -208,6 +208,7 @@ static int hidma_chan_init(struct hidma_dev *dmadev, u32 dma_sig)
 	INIT_LIST_HEAD(&mchan->prepared);
 	INIT_LIST_HEAD(&mchan->active);
 	INIT_LIST_HEAD(&mchan->completed);
+	INIT_LIST_HEAD(&mchan->queued);
 
 	spin_lock_init(&mchan->lock);
 	list_add_tail(&mchan->chan.device_node, &ddev->channels);
@@ -228,9 +229,15 @@ static void hidma_issue_pending(struct dma_chan *dmach)
 	struct hidma_chan *mchan = to_hidma_chan(dmach);
 	struct hidma_dev *dmadev = mchan->dmadev;
 	unsigned long flags;
+	struct hidma_desc *qdesc, *next;
 	int status;
 
 	spin_lock_irqsave(&mchan->lock, flags);
+	list_for_each_entry_safe(qdesc, next, &mchan->queued, node) {
+		hidma_ll_queue_request(dmadev->lldev, qdesc->tre_ch);
+		list_move_tail(&qdesc->node, &mchan->active);
+	}
+
 	if (!mchan->running) {
 		struct hidma_desc *desc = list_first_entry(&mchan->active,
 							   struct hidma_desc,
@@ -313,17 +320,18 @@ static dma_cookie_t hidma_tx_submit(struct dma_async_tx_descriptor *txd)
 		pm_runtime_put_autosuspend(dmadev->ddev.dev);
 		return -ENODEV;
 	}
+	pm_runtime_mark_last_busy(dmadev->ddev.dev);
+	pm_runtime_put_autosuspend(dmadev->ddev.dev);
 
 	mdesc = container_of(txd, struct hidma_desc, desc);
 	spin_lock_irqsave(&mchan->lock, irqflags);
 
-	/* Move descriptor to active */
-	list_move_tail(&mdesc->node, &mchan->active);
+	/* Move descriptor to queued */
+	list_move_tail(&mdesc->node, &mchan->queued);
 
 	/* Update cookie */
 	cookie = dma_cookie_assign(txd);
 
-	hidma_ll_queue_request(dmadev->lldev, mdesc->tre_ch);
 	spin_unlock_irqrestore(&mchan->lock, irqflags);
 
 	return cookie;
@@ -429,6 +437,7 @@ static int hidma_terminate_channel(struct dma_chan *chan)
 	list_splice_init(&mchan->active, &list);
 	list_splice_init(&mchan->prepared, &list);
 	list_splice_init(&mchan->completed, &list);
+	list_splice_init(&mchan->queued, &list);
 	spin_unlock_irqrestore(&mchan->lock, irqflags);
 
 	/* this suspends the existing transfer */
diff --git a/drivers/dma/qcom/hidma.h b/drivers/dma/qcom/hidma.h
index e52e20716303..03775ca940e2 100644
--- a/drivers/dma/qcom/hidma.h
+++ b/drivers/dma/qcom/hidma.h
@@ -103,6 +103,7 @@ struct hidma_chan {
 	struct dma_chan			chan;
 	struct list_head		free;
 	struct list_head		prepared;
+	struct list_head		queued;
 	struct list_head		active;
 	struct list_head		completed;
 
-- 
2.15.1