[3.11.y.z extended stable] Patch "dmaengine: dw: went back to plain {request, free}_irq() calls" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dmaengine: dw: went back to plain {request,free}_irq() calls

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 487b8bc80bb6cc8cfd4520dfe23dd673d25741ba Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Date: Wed, 7 May 2014 10:56:24 +0300
Subject: dmaengine: dw: went back to plain {request,free}_irq() calls

commit 97977f7576a89cb9436c000ae703c0d515e748ac upstream.

The commit dbde5c29 "dw_dmac: use devm_* functions to simplify code" turns
probe function to use devm_* helpers and simultaneously brings a regression. We
need to ensure irq is disabled, followed by ensuring that don't schedule any
more tasklets and then its safe to use tasklet_kill().

The free_irq() will ensure that the irq is disabled and also wait till all
scheduled interrupts are executed by invoking synchronize_irq(). So we need to
only do tasklet_kill() after invoking free_irq().

Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/dma/dw/core.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 1292a6eda60f..884b38b52f02 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1563,11 +1563,6 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 	/* Disable BLOCK interrupts as well */
 	channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);

-	err = devm_request_irq(chip->dev, chip->irq, dw_dma_interrupt,
-			       IRQF_SHARED, "dw_dmac", dw);
-	if (err)
-		return err;
-
 	/* Create a pool of consistent memory blocks for hardware descriptors */
 	dw->desc_pool = dmam_pool_create("dw_dmac_desc_pool", chip->dev,
 					 sizeof(struct dw_desc), 4, 0);
@@ -1578,6 +1573,11 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)

 	tasklet_init(&dw->tasklet, dw_dma_tasklet, (unsigned long)dw);

+	err = request_irq(chip->irq, dw_dma_interrupt, IRQF_SHARED,
+			  "dw_dmac", dw);
+	if (err)
+		return err;
+
 	INIT_LIST_HEAD(&dw->dma.channels);
 	for (i = 0; i < nr_channels; i++) {
 		struct dw_dma_chan	*dwc = &dw->chan[i];
@@ -1680,6 +1680,7 @@ int dw_dma_remove(struct dw_dma_chip *chip)
 	dw_dma_off(dw);
 	dma_async_device_unregister(&dw->dma);

+	free_irq(chip->irq, dw);
 	tasklet_kill(&dw->tasklet);

 	list_for_each_entry_safe(dwc, _dwc, &dw->dma.channels,
--
1.9.1