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: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 1966c52..dc7850a 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -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_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 @@
*/
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 @@
}
}
spin_unlock_irqrestore(&chan->vc.lock, flags);
+ wake_up(&chan->wq_state);
return IRQ_HANDLED;
}
@@ -1267,6 +1272,14 @@
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 @@
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 @@
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);