diff options
| author | Robert Jarzmik <robert.jarzmik@free.fr> | 2016-07-10 21:50:49 (GMT) |
|---|---|---|
| committer | Vinod Koul <vinod.koul@intel.com> | 2016-07-23 10:37:29 (GMT) |
| commit | 7d604663255ac757ab4b0e17f533cba136486551 (patch) | |
| tree | 593d64dd9bb2a23a7e53ae2a0a51f35ccc0b7af0 /drivers/dma | |
| parent | 0d605ba0b8ce7f5963124853774cc9bd84589a99 (diff) | |
| download | linux-7d604663255ac757ab4b0e17f533cba136486551.tar.xz | |
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>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/pxa_dma.c | 15 |
1 files changed, 15 insertions, 0 deletions
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_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); |