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dmaengine: pxa_dma: implement device_synchronize

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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: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Robert Jarzmik 2016-07-10 23:50:49 +02:00 committed by Vinod Koul
parent 0d605ba0b8
commit 7d60466325
1 changed files with 15 additions and 0 deletions
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15
drivers/dma/pxa_dma.c
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@ -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);
wake_up(&chan->wq_state);
}
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);
wake_up(&chan->wq_state);
return IRQ_HANDLED;
}
@ -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));
vchan_synchronize(&chan->vc);
}
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);
init_waitqueue_head(&c->wq_state);
}
return dma_async_device_register(&pdev->slave);