[PATCH v1 5/6] dmaengine: dw: enable and disable controller when needed

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

Enable controller automatically whenever first user requires for a channel and
disable it when the last user gone.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/dma/dw/core.c | 60 ++++++++++++++++++++++++++++++---------------------
 drivers/dma/dw/regs.h |  1 +
 2 files changed, 36 insertions(+), 25 deletions(-)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 4812638..2447221 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1094,6 +1094,31 @@ static void dwc_issue_pending(struct dma_chan *chan)
 	spin_unlock_irqrestore(&dwc->lock, flags);
 }
 
+/*----------------------------------------------------------------------*/
+
+static void dw_dma_off(struct dw_dma *dw)
+{
+	int i;
+
+	dma_writel(dw, CFG, 0);
+
+	channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
+	channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask);
+	channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask);
+	channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);
+
+	while (dma_readl(dw, CFG) & DW_CFG_DMA_EN)
+		cpu_relax();
+
+	for (i = 0; i < dw->dma.chancnt; i++)
+		dw->chan[i].initialized = false;
+}
+
+static void dw_dma_on(struct dw_dma *dw)
+{
+	dma_writel(dw, CFG, DW_CFG_DMA_EN);
+}
+
 static int dwc_alloc_chan_resources(struct dma_chan *chan)
 {
 	struct dw_dma_chan	*dwc = to_dw_dma_chan(chan);
@@ -1118,6 +1143,11 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
 	 * doesn't mean what you think it means), and status writeback.
 	 */
 
+	/* Enable controller here if needed */
+	if (!dw->in_use)
+		dw_dma_on(dw);
+	dw->in_use |= dwc->mask;
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	i = dwc->descs_allocated;
 	while (dwc->descs_allocated < NR_DESCS_PER_CHANNEL) {
@@ -1182,6 +1212,11 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
+	/* Disable controller in case it was a last user */
+	dw->in_use &= ~dwc->mask;
+	if (!dw->in_use)
+		dw_dma_off(dw);
+
 	list_for_each_entry_safe(desc, _desc, &list, desc_node) {
 		dev_vdbg(chan2dev(chan), "  freeing descriptor %p\n", desc);
 		dma_pool_free(dw->desc_pool, desc, desc->txd.phys);
@@ -1452,29 +1487,6 @@ EXPORT_SYMBOL(dw_dma_cyclic_free);
 
 /*----------------------------------------------------------------------*/
 
-static void dw_dma_off(struct dw_dma *dw)
-{
-	int i;
-
-	dma_writel(dw, CFG, 0);
-
-	channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
-	channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask);
-	channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask);
-	channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);
-
-	while (dma_readl(dw, CFG) & DW_CFG_DMA_EN)
-		cpu_relax();
-
-	for (i = 0; i < dw->dma.chancnt; i++)
-		dw->chan[i].initialized = false;
-}
-
-static void dw_dma_on(struct dw_dma *dw)
-{
-	dma_writel(dw, CFG, DW_CFG_DMA_EN);
-}
-
 int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 {
 	struct dw_dma		*dw;
@@ -1648,8 +1660,6 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 	dw->dma.device_tx_status = dwc_tx_status;
 	dw->dma.device_issue_pending = dwc_issue_pending;
 
-	dw_dma_on(dw);
-
 	err = dma_async_device_register(&dw->dma);
 	if (err)
 		goto err_dma_register;
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index e8f92b2..848e232 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -281,6 +281,7 @@ struct dw_dma {
 	/* channels */
 	struct dw_dma_chan	*chan;
 	u8			all_chan_mask;
+	u8			in_use;
 
 	/* hardware configuration */
 	unsigned char		nr_masters;
-- 
2.1.0

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