Commit 7d604663 authored by Robert Jarzmik's avatar Robert Jarzmik Committed by Vinod Koul

dmaengine: pxa_dma: implement device_synchronize

Implement the function which wait until a dma channel is stopped to have
a synchronization point.

This also protects the pxad_remove() from races, such as spurious
interrupts while removing the driver, because :
 - as long as there is one dma channel requested, ie. dma_chan_get() but
   no dma_chan_put(), the try_module_get() of dma_chan_get() prevents
   the remove() routine from running
 - when the last channel is released, ie. the last dma_chan_put() is
   called, if there is a running DMA, pxad_synchronize() is called
 - pxad_synchronize() waits for the channel to stop, which in turn
   ensures on pxa architecture that the interrupt cannot be fired anymore
Reported-by: default avatarVinod Koul <>
Signed-off-by: default avatarRobert Jarzmik <>
Signed-off-by: default avatarVinod Koul <>
parent 0d605ba0
......@@ -21,6 +21,7 @@
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/of.h>
#include <linux/wait.h>
#include <linux/dma/pxa-dma.h>
#include "dmaengine.h"
......@@ -118,6 +119,8 @@ struct pxad_chan {
struct pxad_phy *phy;
struct dma_pool *desc_pool; /* Descriptors pool */
dma_cookie_t bus_error;
wait_queue_head_t wq_state;
struct pxad_device {
......@@ -571,6 +574,7 @@ static void pxad_launch_chan(struct pxad_chan *chan,
phy_writel(chan->phy, desc->first, DDADR);
phy_enable(chan->phy, chan->misaligned);
static void set_updater_desc(struct pxad_desc_sw *sw_desc,
......@@ -716,6 +720,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id)
spin_unlock_irqrestore(&chan->vc.lock, flags);
......@@ -1267,6 +1272,14 @@ static enum dma_status pxad_tx_status(struct dma_chan *dchan,
return ret;
static void pxad_synchronize(struct dma_chan *dchan)
struct pxad_chan *chan = to_pxad_chan(dchan);
wait_event(chan->wq_state, !is_chan_running(chan));
static void pxad_free_channels(struct dma_device *dmadev)
struct pxad_chan *c, *cn;
......@@ -1371,6 +1384,7 @@ static int pxad_init_dmadev(struct platform_device *op,
pdev->slave.device_tx_status = pxad_tx_status;
pdev->slave.device_issue_pending = pxad_issue_pending;
pdev->slave.device_config = pxad_config;
pdev->slave.device_synchronize = pxad_synchronize;
pdev->slave.device_terminate_all = pxad_terminate_all;
if (op->dev.coherent_dma_mask)
......@@ -1388,6 +1402,7 @@ static int pxad_init_dmadev(struct platform_device *op,
return -ENOMEM;
c->vc.desc_free = pxad_free_desc;
vchan_init(&c->vc, &pdev->slave);
return dma_async_device_register(&pdev->slave);
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