Skip to contentSkip to conversation

Patch "dmaengine: dw: disable BLOCK IRQs for non-cyclic xfer" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Mar 1, 2016

Subsystems (3)
Stable branch dmaengine Synopsys DesignWare DMAC driver
lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

This is a note to let you know that I've just added the patch titled

dmaengine: dw: disable BLOCK IRQs for non-cyclic xfer

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dmaengine-dw-disable-block-irqs-for-non-cyclic-xfer.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From ee1cdcdae59563535485a5f56ee72c894ab7d7ad Mon Sep 17 00:00:00 2001

From: Andy Shevchenko <[email protected]>
Date: Wed, 10 Feb 2016 15:59:42 +0200
Subject: dmaengine: dw: disable BLOCK IRQs for non-cyclic xfer

From: Andy Shevchenko <[email protected]>

commit ee1cdcdae59563535485a5f56ee72c894ab7d7ad upstream.

The commit 2895b2cad6e7 ("dmaengine: dw: fix cyclic transfer callbacks") re-enabled BLOCK interrupts with regard to make cyclic transfers work. However, this change becomes a regression for non-cyclic transfers as interrupt counters under stress test had been grown enormously (approximately per 4-5 bytes in the UART loop back test).

Taking into consideration above enable BLOCK interrupts if and only if channel is programmed to perform cyclic transfer.

Fixes 2895b2cad6e7 ("dmaengine: dw: fix cyclic transfer callbacks")
Signed-off-by Andy Shevchenko <[email protected]>
Acked-by Mans Rullgard <[email protected]>
Tested-by Mans Rullgard <[email protected]>
Acked-by Viresh Kumar <[email protected]>
Signed-off-by Vinod Koul <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/dma/dw/core.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)
drivers/dma/dw/core.c +10 -5
@@ -156,7 +156,6 @@ static void dwc_initialize(struct dw_dma
 
 	/* Enable interrupts */
 	channel_set_bit(dw, MASK.XFER, dwc->mask);
-	channel_set_bit(dw, MASK.BLOCK, dwc->mask);
 	channel_set_bit(dw, MASK.ERROR, dwc->mask);
 
 	dwc->initialized = true;

@@ -588,6 +587,9 @@ static void dwc_handle_cyclic(struct dw_
 
 		spin_unlock_irqrestore(&dwc->lock, flags);
 	}
+
+	/* Re-enable interrupts */
+	channel_set_bit(dw, MASK.BLOCK, dwc->mask);
 }
 
 /* ------------------------------------------------------------------------- */

@@ -618,11 +620,8 @@ static void dw_dma_tasklet(unsigned long
 			dwc_scan_descriptors(dw, dwc);
 	}
 
-	/*
-	 * Re-enable interrupts.
-	 */
+	/* Re-enable interrupts */
 	channel_set_bit(dw, MASK.XFER, dw->all_chan_mask);
-	channel_set_bit(dw, MASK.BLOCK, dw->all_chan_mask);
 	channel_set_bit(dw, MASK.ERROR, dw->all_chan_mask);
 }
 

@@ -1256,6 +1255,7 @@ static void dwc_free_chan_resources(stru
 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(chan->device);
 	unsigned long		flags;
 
 	if (!test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) {

@@ -1264,7 +1264,12 @@ int dw_dma_cyclic_start(struct dma_chan
 	}
 
 	spin_lock_irqsave(&dwc->lock, flags);
+
+	/* Enable interrupts to perform cyclic transfer */
+	channel_set_bit(dw, MASK.BLOCK, dwc->mask);
+
 	dwc_dostart(dwc, dwc->cdesc->desc[0]);
+
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/dmaengine-dw-disable-block-irqs-for-non-cyclic-xfer.patch