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

[Kamal Mostafa]

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-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 39e469e77a8d06b2104ac09131822530658819a4 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: Kamal Mostafa <kamal 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 7516be4..42c208d 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1546,11 +1546,6 @@ 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);
@@ -1561,6 +1556,11 @@ 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];
@@ -1663,6 +1663,7 @@ 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