@@ -24,6 +24,7 @@
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/slab.h>
+#include <linux/wait.h>
#include "dmaengine.h"
@@ -202,6 +203,8 @@ struct tegra_dma_channel {
unsigned int slave_id;
struct dma_slave_config dma_sconfig;
struct tegra_dma_channel_regs channel_reg;
+
+ struct wait_queue_head wq;
};
/* tegra_dma: Tegra DMA specific information */
@@ -682,6 +685,7 @@ static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
tdc_write(tdc, TEGRA_APBDMA_CHAN_STATUS, status);
tdc->isr_handler(tdc, false);
tasklet_schedule(&tdc->tasklet);
+ wake_up_all(&tdc->wq);
spin_unlock(&tdc->lock);
return IRQ_HANDLED;
}
@@ -783,6 +787,7 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
tegra_dma_resume(tdc);
pm_runtime_put(tdc->tdma->dev);
+ wake_up_all(&tdc->wq);
skip_dma_stop:
tegra_dma_abort_all(tdc);
@@ -798,10 +803,29 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
return 0;
}
+static bool tegra_dma_eoc_interrupt_deasserted(struct tegra_dma_channel *tdc)
+{
+ unsigned long flags;
+ u32 status;
+
+ spin_lock_irqsave(&tdc->lock, flags);
+ status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
+ spin_unlock_irqrestore(&tdc->lock, flags);
+
+ return !(status & TEGRA_APBDMA_STATUS_ISE_EOC);
+}
+
static void tegra_dma_synchronize(struct dma_chan *dc)
{
struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+ /*
+ * CPU, which handles interrupt, could be busy in
+ * uninterruptible state, in this case sibling CPU
+ * should wait until interrupt is handled.
+ */
+ wait_event(tdc->wq, tegra_dma_eoc_interrupt_deasserted(tdc));
+
tasklet_kill(&tdc->tasklet);
}
@@ -1495,6 +1519,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
tasklet_init(&tdc->tasklet, tegra_dma_tasklet,
(unsigned long)tdc);
spin_lock_init(&tdc->lock);
+ init_waitqueue_head(&tdc->wq);
INIT_LIST_HEAD(&tdc->pending_sg_req);
INIT_LIST_HEAD(&tdc->free_sg_req);
Boot CPU0 always handles DMA interrupts and under some rare circumstances it could stuck in uninterruptible state for a significant time (like in a case of KASAN + NFS root). In this case sibling CPU, which waits for DMA transfer completion, will get a DMA transfer timeout. In order to handle this rare condition, interrupt status needs to be polled until interrupt is handled. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- Changelog: v2: Added forgotten wake_up_all() to tegra_dma_terminate_all(), which will wake up waiting threads after transfer's abortion. drivers/dma/tegra20-apb-dma.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)