Merge branch 'fix/brcm' into fixes

1 files changed, 25 insertions, 45 deletions

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 1a44c8086d77..ae10f5614f95 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -406,38 +406,32 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
         }
 }
 
-static int bcm2835_dma_abort(void __iomem *chan_base)
+static int bcm2835_dma_abort(struct bcm2835_chan *c)
 {
-        unsigned long cs;
+        void __iomem *chan_base = c->chan_base;
         long int timeout = 10000;
 
-        cs = readl(chan_base + BCM2835_DMA_CS);
-        if (!(cs & BCM2835_DMA_ACTIVE))
+        /*
+         * A zero control block address means the channel is idle.
+         * (The ACTIVE flag in the CS register is not a reliable indicator.)
+         */
+        if (!readl(chan_base + BCM2835_DMA_ADDR))
                 return 0;
 
         /* Write 0 to the active bit - Pause the DMA */
         writel(0, chan_base + BCM2835_DMA_CS);
 
         /* Wait for any current AXI transfer to complete */
-        while ((cs & BCM2835_DMA_ISPAUSED) && --timeout) {
+        while ((readl(chan_base + BCM2835_DMA_CS) &
+                BCM2835_DMA_WAITING_FOR_WRITES) && --timeout)
                 cpu_relax();
-                cs = readl(chan_base + BCM2835_DMA_CS);
-        }
 
-        /* We'll un-pause when we set of our next DMA */
+        /* Peripheral might be stuck and fail to signal AXI write responses */
         if (!timeout)
-                return -ETIMEDOUT;
-
-        if (!(cs & BCM2835_DMA_ACTIVE))
-                return 0;
-
-        /* Terminate the control block chain */
-        writel(0, chan_base + BCM2835_DMA_NEXTCB);
-
-        /* Abort the whole DMA */
-        writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
-               chan_base + BCM2835_DMA_CS);
+                dev_err(c->vc.chan.device->dev,
+                        "failed to complete outstanding writes\n");
 
+        writel(BCM2835_DMA_RESET, chan_base + BCM2835_DMA_CS);
         return 0;
 }
 
@@ -476,8 +470,15 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
 
         spin_lock_irqsave(&c->vc.lock, flags);
 
-        /* Acknowledge interrupt */
-        writel(BCM2835_DMA_INT, c->chan_base + BCM2835_DMA_CS);
+        /*
+         * Clear the INT flag to receive further interrupts. Keep the channel
+         * active in case the descriptor is cyclic or in case the client has
+         * already terminated the descriptor and issued a new one. (May happen
+         * if this IRQ handler is threaded.) If the channel is finished, it
+         * will remain idle despite the ACTIVE flag being set.
+         */
+        writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE,
+               c->chan_base + BCM2835_DMA_CS);
 
         d = c->desc;
 
@@ -485,11 +486,7 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
                 if (d->cyclic) {
                         /* call the cyclic callback */
                         vchan_cyclic_callback(&d->vd);
-
-                        /* Keep the DMA engine running */
-                        writel(BCM2835_DMA_ACTIVE,
-                               c->chan_base + BCM2835_DMA_CS);
-                } else {
+                } else if (!readl(c->chan_base + BCM2835_DMA_ADDR)) {
                         vchan_cookie_complete(&c->desc->vd);
                         bcm2835_dma_start_desc(c);
                 }
@@ -779,7 +776,6 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
         struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
         unsigned long flags;
-        int timeout = 10000;
         LIST_HEAD(head);
 
         spin_lock_irqsave(&c->vc.lock, flags);
@@ -789,27 +785,11 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
         list_del_init(&c->node);
         spin_unlock(&d->lock);
 
-        /*
-         * Stop DMA activity: we assume the callback will not be called
-         * after bcm_dma_abort() returns (even if it does, it will see
-         * c->desc is NULL and exit.)
-         */
+        /* stop DMA activity */
         if (c->desc) {
                 vchan_terminate_vdesc(&c->desc->vd);
                 c->desc = NULL;
-                bcm2835_dma_abort(c->chan_base);
-
-                /* Wait for stopping */
-                while (--timeout) {
-                        if (!(readl(c->chan_base + BCM2835_DMA_CS) &
-                                                BCM2835_DMA_ACTIVE))
-                                break;
-
-                        cpu_relax();
-                }
-
-                if (!timeout)
-                        dev_err(d->ddev.dev, "DMA transfer could not be terminated\n");
+                bcm2835_dma_abort(c);
         }
 
         vchan_get_all_descriptors(&c->vc, &head);