Merge branch 'coh' into dmaengine

7 files changed, 116 insertions, 123 deletions

diff --git a/arch/arm/mach-u300/include/mach/coh901318.h b/arch/arm/mach-u300/include/mach/coh901318.h
index f4cfee9c7d28..b8155b4e5ffa 100644
--- a/arch/arm/mach-u300/include/mach/coh901318.h
+++ b/arch/arm/mach-u300/include/mach/coh901318.h
@@ -53,7 +53,7 @@ struct coh901318_params {
  * struct coh_dma_channel - dma channel base
  * @name: ascii name of dma channel
  * @number: channel id number
- * @desc_nbr_max: number of preallocated descriptortors
+ * @desc_nbr_max: number of preallocated descriptors
  * @priority_high: prio of channel, 0 low otherwise high.
  * @param: configuration parameters
  * @dev_addr: physical address of periphal connected to channel
diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
index b5f2ee0f8e2c..1656fdcdb6c2 100644
--- a/drivers/dma/coh901318.c
+++ b/drivers/dma/coh901318.c
@@ -39,7 +39,6 @@ struct coh901318_desc {
         unsigned int sg_len;
         struct coh901318_lli *data;
         enum dma_data_direction dir;
-        int pending_irqs;
         unsigned long flags;
 };
 
@@ -72,7 +71,6 @@ struct coh901318_chan {
 
         unsigned long nbr_active_done;
         unsigned long busy;
-        int pending_irqs;
 
         struct coh901318_base *base;
 };
@@ -80,18 +78,16 @@ struct coh901318_chan {
 static void coh901318_list_print(struct coh901318_chan *cohc,
                                  struct coh901318_lli *lli)
 {
-        struct coh901318_lli *l;
-        dma_addr_t addr =  virt_to_phys(lli);
+        struct coh901318_lli *l = lli;
         int i = 0;
 
-        while (addr) {
-                l = phys_to_virt(addr);
+        while (l) {
                 dev_vdbg(COHC_2_DEV(cohc), "i %d, lli %p, ctrl 0x%x, src 0x%x"
-                         ", dst 0x%x, link 0x%x link_virt 0x%p\n",
+                         ", dst 0x%x, link 0x%x virt_link_addr 0x%p\n",
                          i, l, l->control, l->src_addr, l->dst_addr,
-                         l->link_addr, phys_to_virt(l->link_addr));
+                         l->link_addr, l->virt_link_addr);
                 i++;
-                addr = l->link_addr;
+                l = l->virt_link_addr;
         }
 }
 
@@ -125,7 +121,7 @@ static int coh901318_debugfs_read(struct file *file, char __user *buf,
                 goto err_kmalloc;
         tmp = dev_buf;
 
-        tmp += sprintf(tmp, "DMA -- enable dma channels\n");
+        tmp += sprintf(tmp, "DMA -- enabled dma channels\n");
 
         for (i = 0; i < debugfs_dma_base->platform->max_channels; i++)
                 if (started_channels & (1 << i))
@@ -337,16 +333,22 @@ coh901318_desc_get(struct coh901318_chan *cohc)
                  * TODO: alloc a pile of descs instead of just one,
                  * avoid many small allocations.
                  */
-                desc = kmalloc(sizeof(struct coh901318_desc), GFP_NOWAIT);
+                desc = kzalloc(sizeof(struct coh901318_desc), GFP_NOWAIT);
                 if (desc == NULL)
                         goto out;
                 INIT_LIST_HEAD(&desc->node);
+                dma_async_tx_descriptor_init(&desc->desc, &cohc->chan);
         } else {
                 /* Reuse an old desc. */
                 desc = list_first_entry(&cohc->free,
                                         struct coh901318_desc,
                                         node);
                 list_del(&desc->node);
+                /* Initialize it a bit so it's not insane */
+                desc->sg = NULL;
+                desc->sg_len = 0;
+                desc->desc.callback = NULL;
+                desc->desc.callback_param = NULL;
         }
 
  out:
@@ -364,10 +366,6 @@ static void
 coh901318_desc_submit(struct coh901318_chan *cohc, struct coh901318_desc *desc)
 {
         list_add_tail(&desc->node, &cohc->active);
-
-        BUG_ON(cohc->pending_irqs != 0);
-
-        cohc->pending_irqs = desc->pending_irqs;
 }
 
 static struct coh901318_desc *
@@ -592,6 +590,10 @@ static struct coh901318_desc *coh901318_queue_start(struct coh901318_chan *cohc)
         return cohd_que;
 }
 
+/*
+ * This tasklet is called from the interrupt handler to
+ * handle each descriptor (DMA job) that is sent to a channel.
+ */
 static void dma_tasklet(unsigned long data)
 {
         struct coh901318_chan *cohc = (struct coh901318_chan *) data;
@@ -600,57 +602,58 @@ static void dma_tasklet(unsigned long data)
         dma_async_tx_callback callback;
         void *callback_param;
 
+        dev_vdbg(COHC_2_DEV(cohc), "[%s] chan_id %d"
+                 " nbr_active_done %ld\n", __func__,
+                 cohc->id, cohc->nbr_active_done);
+
         spin_lock_irqsave(&cohc->lock, flags);
 
-        /* get first active entry from list */
+        /* get first active descriptor entry from list */
         cohd_fin = coh901318_first_active_get(cohc);
 
-        BUG_ON(cohd_fin->pending_irqs == 0);
-
         if (cohd_fin == NULL)
                 goto err;
 
-        cohd_fin->pending_irqs--;
-        cohc->completed = cohd_fin->desc.cookie;
-
-        BUG_ON(cohc->nbr_active_done && cohd_fin == NULL);
-
-        if (cohc->nbr_active_done == 0)
-                return;
+        /* locate callback to client */
+        callback = cohd_fin->desc.callback;
+        callback_param = cohd_fin->desc.callback_param;
 
-        if (!cohd_fin->pending_irqs) {
-                /* release the lli allocation*/
-                coh901318_lli_free(&cohc->base->pool, &cohd_fin->data);
-        }
+        /* sign this job as completed on the channel */
+        cohc->completed = cohd_fin->desc.cookie;
 
-        dev_vdbg(COHC_2_DEV(cohc), "[%s] chan_id %d pending_irqs %d"
-                 " nbr_active_done %ld\n", __func__,
-                 cohc->id, cohc->pending_irqs, cohc->nbr_active_done);
+        /* release the lli allocation and remove the descriptor */
+        coh901318_lli_free(&cohc->base->pool, &cohd_fin->data);
 
-        /* callback to client */
-        callback = cohd_fin->desc.callback;
-        callback_param = cohd_fin->desc.callback_param;
+        /* return desc to free-list */
+        coh901318_desc_remove(cohd_fin);
+        coh901318_desc_free(cohc, cohd_fin);
 
-        if (!cohd_fin->pending_irqs) {
-                coh901318_desc_remove(cohd_fin);
+        spin_unlock_irqrestore(&cohc->lock, flags);
 
-                /* return desc to free-list */
-                coh901318_desc_free(cohc, cohd_fin);
-        }
+        /* Call the callback when we're done */
+        if (callback)
+                callback(callback_param);
 
-        if (cohc->nbr_active_done)
-                cohc->nbr_active_done--;
+        spin_lock_irqsave(&cohc->lock, flags);
 
+        /*
+         * If another interrupt fired while the tasklet was scheduling,
+         * we don't get called twice, so we have this number of active
+         * counter that keep track of the number of IRQs expected to
+         * be handled for this channel. If there happen to be more than
+         * one IRQ to be ack:ed, we simply schedule this tasklet again.
+         */
+        cohc->nbr_active_done--;
         if (cohc->nbr_active_done) {
+                dev_dbg(COHC_2_DEV(cohc), "scheduling tasklet again, new IRQs "
+                        "came in while we were scheduling this tasklet\n");
                 if (cohc_chan_conf(cohc)->priority_high)
                         tasklet_hi_schedule(&cohc->tasklet);
                 else
                         tasklet_schedule(&cohc->tasklet);
         }
-        spin_unlock_irqrestore(&cohc->lock, flags);
 
-        if (callback)
-                callback(callback_param);
+        spin_unlock_irqrestore(&cohc->lock, flags);
 
         return;
 
@@ -669,16 +672,17 @@ static void dma_tc_handle(struct coh901318_chan *cohc)
         if (!cohc->allocated)
                 return;
 
-        BUG_ON(cohc->pending_irqs == 0);
+        spin_lock(&cohc->lock);
 
-        cohc->pending_irqs--;
         cohc->nbr_active_done++;
 
-        if (cohc->pending_irqs == 0 && coh901318_queue_start(cohc) == NULL)
+        if (coh901318_queue_start(cohc) == NULL)
                 cohc->busy = 0;
 
         BUG_ON(list_empty(&cohc->active));
 
+        spin_unlock(&cohc->lock);
+
         if (cohc_chan_conf(cohc)->priority_high)
                 tasklet_hi_schedule(&cohc->tasklet);
         else
@@ -872,6 +876,7 @@ coh901318_prep_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
         struct coh901318_chan *cohc = to_coh901318_chan(chan);
         int lli_len;
         u32 ctrl_last = cohc_chan_param(cohc)->ctrl_lli_last;
+        int ret;
 
         spin_lock_irqsave(&cohc->lock, flg);
 
@@ -892,22 +897,19 @@ coh901318_prep_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
         if (data == NULL)
                 goto err;
 
-        cohd = coh901318_desc_get(cohc);
-        cohd->sg = NULL;
-        cohd->sg_len = 0;
-        cohd->data = data;
-
-        cohd->pending_irqs =
-                coh901318_lli_fill_memcpy(
-                                &cohc->base->pool, data, src, size, dest,
-                                cohc_chan_param(cohc)->ctrl_lli_chained,
-                                ctrl_last);
-        cohd->flags = flags;
+        ret = coh901318_lli_fill_memcpy(
+                &cohc->base->pool, data, src, size, dest,
+                cohc_chan_param(cohc)->ctrl_lli_chained,
+                ctrl_last);
+        if (ret)
+                goto err;
 
         COH_DBG(coh901318_list_print(cohc, data));
 
-        dma_async_tx_descriptor_init(&cohd->desc, chan);
-
+        /* Pick a descriptor to handle this transfer */
+        cohd = coh901318_desc_get(cohc);
+        cohd->data = data;
+        cohd->flags = flags;
         cohd->desc.tx_submit = coh901318_tx_submit;
 
         spin_unlock_irqrestore(&cohc->lock, flg);
@@ -926,6 +928,7 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
         struct coh901318_chan *cohc = to_coh901318_chan(chan);
         struct coh901318_lli *data;
         struct coh901318_desc *cohd;
+        const struct coh901318_params *params;
         struct scatterlist *sg;
         int len = 0;
         int size;
@@ -933,7 +936,9 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
         u32 ctrl_chained = cohc_chan_param(cohc)->ctrl_lli_chained;
         u32 ctrl = cohc_chan_param(cohc)->ctrl_lli;
         u32 ctrl_last = cohc_chan_param(cohc)->ctrl_lli_last;
+        u32 config;
         unsigned long flg;
+        int ret;
 
         if (!sgl)
                 goto out;
@@ -949,15 +954,14 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 /* Trigger interrupt after last lli */
                 ctrl_last |= COH901318_CX_CTRL_TC_IRQ_ENABLE;
 
-        cohd = coh901318_desc_get(cohc);
-        cohd->sg = NULL;
-        cohd->sg_len = 0;
-        cohd->dir = direction;
+        params = cohc_chan_param(cohc);
+        config = params->config;
 
         if (direction == DMA_TO_DEVICE) {
                 u32 tx_flags = COH901318_CX_CTRL_PRDD_SOURCE |
                         COH901318_CX_CTRL_SRC_ADDR_INC_ENABLE;
 
+                config |= COH901318_CX_CFG_RM_MEMORY_TO_PRIMARY;
                 ctrl_chained |= tx_flags;
                 ctrl_last |= tx_flags;
                 ctrl |= tx_flags;
@@ -965,16 +969,14 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 u32 rx_flags = COH901318_CX_CTRL_PRDD_DEST |
                         COH901318_CX_CTRL_DST_ADDR_INC_ENABLE;
 
+                config |= COH901318_CX_CFG_RM_PRIMARY_TO_MEMORY;
                 ctrl_chained |= rx_flags;
                 ctrl_last |= rx_flags;
                 ctrl |= rx_flags;
         } else
                 goto err_direction;
 
-        dma_async_tx_descriptor_init(&cohd->desc, chan);
-
-        cohd->desc.tx_submit = coh901318_tx_submit;
-
+        coh901318_set_conf(cohc, config);
 
         /* The dma only supports transmitting packages up to
          * MAX_DMA_PACKET_SIZE. Calculate to total number of
@@ -996,32 +998,37 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 len += factor;
         }
 
+        pr_debug("Allocate %d lli:s for this transfer\n", len);
         data = coh901318_lli_alloc(&cohc->base->pool, len);
 
         if (data == NULL)
                 goto err_dma_alloc;
 
         /* initiate allocated data list */
-        cohd->pending_irqs =
-                coh901318_lli_fill_sg(&cohc->base->pool, data, sgl, sg_len,
-                                      cohc_dev_addr(cohc),
-                                      ctrl_chained,
-                                      ctrl,
-                                      ctrl_last,
-                                      direction, COH901318_CX_CTRL_TC_IRQ_ENABLE);
-        cohd->data = data;
-
-        cohd->flags = flags;
+        ret = coh901318_lli_fill_sg(&cohc->base->pool, data, sgl, sg_len,
+                                    cohc_dev_addr(cohc),
+                                    ctrl_chained,
+                                    ctrl,
+                                    ctrl_last,
+                                    direction, COH901318_CX_CTRL_TC_IRQ_ENABLE);
+        if (ret)
+                goto err_lli_fill;
 
         COH_DBG(coh901318_list_print(cohc, data));
 
+        /* Pick a descriptor to handle this transfer */
+        cohd = coh901318_desc_get(cohc);
+        cohd->dir = direction;
+        cohd->flags = flags;
+        cohd->desc.tx_submit = coh901318_tx_submit;
+        cohd->data = data;
+
         spin_unlock_irqrestore(&cohc->lock, flg);
 
         return &cohd->desc;
+ err_lli_fill:
  err_dma_alloc:
  err_direction:
-        coh901318_desc_remove(cohd);
-        coh901318_desc_free(cohc, cohd);
         spin_unlock_irqrestore(&cohc->lock, flg);
  out:
         return NULL;
@@ -1094,9 +1101,8 @@ coh901318_terminate_all(struct dma_chan *chan)
                 /* release the lli allocation*/
                 coh901318_lli_free(&cohc->base->pool, &cohd->data);
 
-                coh901318_desc_remove(cohd);
-
                 /* return desc to free-list */
+                coh901318_desc_remove(cohd);
                 coh901318_desc_free(cohc, cohd);
         }
 
@@ -1104,16 +1110,14 @@ coh901318_terminate_all(struct dma_chan *chan)
                 /* release the lli allocation*/
                 coh901318_lli_free(&cohc->base->pool, &cohd->data);
 
-                coh901318_desc_remove(cohd);
-
                 /* return desc to free-list */
+                coh901318_desc_remove(cohd);
                 coh901318_desc_free(cohc, cohd);
         }
 
 
         cohc->nbr_active_done = 0;
         cohc->busy = 0;
-        cohc->pending_irqs = 0;
 
         spin_unlock_irqrestore(&cohc->lock, flags);
 }
@@ -1140,7 +1144,6 @@ void coh901318_base_init(struct dma_device *dma, const int *pick_chans,
 
                         spin_lock_init(&cohc->lock);
 
-                        cohc->pending_irqs = 0;
                         cohc->nbr_active_done = 0;
                         cohc->busy = 0;
                         INIT_LIST_HEAD(&cohc->free);
@@ -1256,12 +1259,17 @@ static int __init coh901318_probe(struct platform_device *pdev)
         base->dma_memcpy.device_issue_pending = coh901318_issue_pending;
         base->dma_memcpy.device_terminate_all = coh901318_terminate_all;
         base->dma_memcpy.dev = &pdev->dev;
+        /*
+         * This controller can only access address at even 32bit boundaries,
+         * i.e. 2^2
+         */
+        base->dma_memcpy.copy_align = 2;
         err = dma_async_device_register(&base->dma_memcpy);
 
         if (err)
                 goto err_register_memcpy;
 
-        dev_dbg(&pdev->dev, "Initialized COH901318 DMA on virtual base 0x%08x\n",
+        dev_info(&pdev->dev, "Initialized COH901318 DMA on virtual base 0x%08x\n",
                 (u32) base->virtbase);
 
         return err;
diff --git a/drivers/dma/coh901318_lli.c b/drivers/dma/coh901318_lli.c
index f5120f238a4d..71d58c1a1e86 100644
--- a/drivers/dma/coh901318_lli.c
+++ b/drivers/dma/coh901318_lli.c
@@ -74,6 +74,8 @@ coh901318_lli_alloc(struct coh901318_pool *pool, unsigned int len)
 
         lli = head;
         lli->phy_this = phy;
+        lli->link_addr = 0x00000000;
+        lli->virt_link_addr = 0x00000000U;
 
         for (i = 1; i < len; i++) {
                 lli_prev = lli;
@@ -85,13 +87,13 @@ coh901318_lli_alloc(struct coh901318_pool *pool, unsigned int len)
 
                 DEBUGFS_POOL_COUNTER_ADD(pool, 1);
                 lli->phy_this = phy;
+                lli->link_addr = 0x00000000;
+                lli->virt_link_addr = 0x00000000U;
 
                 lli_prev->link_addr = phy;
                 lli_prev->virt_link_addr = lli;
         }
 
-        lli->link_addr = 0x00000000U;
-
         spin_unlock(&pool->lock);
 
         return head;
@@ -166,8 +168,7 @@ coh901318_lli_fill_memcpy(struct coh901318_pool *pool,
         lli->src_addr = src;
         lli->dst_addr = dst;
 
-        /* One irq per single transfer */
-        return 1;
+        return 0;
 }
 
 int
@@ -223,8 +224,7 @@ coh901318_lli_fill_single(struct coh901318_pool *pool,
         lli->src_addr = src;
         lli->dst_addr = dst;
 
-        /* One irq per single transfer */
-        return 1;
+        return 0;
 }
 
 int
@@ -240,7 +240,6 @@ coh901318_lli_fill_sg(struct coh901318_pool *pool,
         u32 ctrl_sg;
         dma_addr_t src = 0;
         dma_addr_t dst = 0;
-        int nbr_of_irq = 0;
         u32 bytes_to_transfer;
         u32 elem_size;
 
@@ -269,15 +268,12 @@ coh901318_lli_fill_sg(struct coh901318_pool *pool,
                         ctrl_sg = ctrl ? ctrl : ctrl_last;
 
 
-                if ((ctrl_sg & ctrl_irq_mask))
-                        nbr_of_irq++;
-
                 if (dir == DMA_TO_DEVICE)
                         /* increment source address */
-                        src = sg_dma_address(sg);
+                        src = sg_phys(sg);
                 else
                         /* increment destination address */
-                        dst =  sg_dma_address(sg);
+                        dst =  sg_phys(sg);
 
                 bytes_to_transfer = sg_dma_len(sg);
 
@@ -310,8 +306,7 @@ coh901318_lli_fill_sg(struct coh901318_pool *pool,
         }
         spin_unlock(&pool->lock);
 
-        /* There can be many IRQs per sg transfer */
-        return nbr_of_irq;
+        return 0;
  err:
         spin_unlock(&pool->lock);
         return -EINVAL;
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 6f51a0a7a8bb..e7a3230fb7d5 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -826,6 +826,7 @@ void dma_async_device_unregister(struct dma_device *device)
                 chan->dev->chan = NULL;
                 mutex_unlock(&dma_list_mutex);
                 device_unregister(&chan->dev->device);
+                free_percpu(chan->local);
         }
 }
 EXPORT_SYMBOL(dma_async_device_unregister);
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 8e409fb50fc0..6fa55fe3dd24 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -467,7 +467,7 @@ err_srcs:
 
         if (iterations > 0)
                 while (!kthread_should_stop()) {
-                        DECLARE_WAIT_QUEUE_HEAD(wait_dmatest_exit);
+                        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wait_dmatest_exit);
                         interruptible_sleep_on(&wait_dmatest_exit);
                 }
 
diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index 25a3c72b2941..1ed5d66d7dca 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -241,7 +241,7 @@ int ioat2_quiesce(struct ioat_chan_common *chan, unsigned long tmo)
         if (is_ioat_active(status) || is_ioat_idle(status))
                 ioat_suspend(chan);
         while (is_ioat_active(status) || is_ioat_idle(status)) {
-                if (end && time_after(jiffies, end)) {
+                if (tmo && time_after(jiffies, end)) {
                         err = -ETIMEDOUT;
                         break;
                 }
diff --git a/drivers/dma/ipu/ipu_idmac.c b/drivers/dma/ipu/ipu_idmac.c
index 1c518f1cc49b..2a446397c884 100644
--- a/drivers/dma/ipu/ipu_idmac.c
+++ b/drivers/dma/ipu/ipu_idmac.c
@@ -748,12 +748,10 @@ static void ipu_select_buffer(enum ipu_channel channel, int buffer_n)
  * @buffer_n:   buffer number to update.
  *              0 or 1 are the only valid values.
  * @phyaddr:    buffer physical address.
- * @return:     Returns 0 on success or negative error code on failure. This
- *              function will fail if the buffer is set to ready.
  */
 /* Called under spin_lock(_irqsave)(&ichan->lock) */
-static int ipu_update_channel_buffer(struct idmac_channel *ichan,
-                                     int buffer_n, dma_addr_t phyaddr)
+static void ipu_update_channel_buffer(struct idmac_channel *ichan,
+                                      int buffer_n, dma_addr_t phyaddr)
 {
         enum ipu_channel channel = ichan->dma_chan.chan_id;
         uint32_t reg;
@@ -793,8 +791,6 @@ static int ipu_update_channel_buffer(struct idmac_channel *ichan,
         }
 
         spin_unlock_irqrestore(&ipu_data.lock, flags);
-
-        return 0;
 }
 
 /* Called under spin_lock_irqsave(&ichan->lock) */
@@ -803,7 +799,6 @@ static int ipu_submit_buffer(struct idmac_channel *ichan,
 {
         unsigned int chan_id = ichan->dma_chan.chan_id;
         struct device *dev = &ichan->dma_chan.dev->device;
-        int ret;
 
         if (async_tx_test_ack(&desc->txd))
                 return -EINTR;
@@ -814,14 +809,7 @@ static int ipu_submit_buffer(struct idmac_channel *ichan,
          * could make it conditional on status >= IPU_CHANNEL_ENABLED, but
          * doing it again shouldn't hurt either.
          */
-        ret = ipu_update_channel_buffer(ichan, buf_idx,
-                                        sg_dma_address(sg));
-
-        if (ret < 0) {
-                dev_err(dev, "Updating sg %p on channel 0x%x buffer %d failed!\n",
-                        sg, chan_id, buf_idx);
-                return ret;
-        }
+        ipu_update_channel_buffer(ichan, buf_idx, sg_dma_address(sg));
 
         ipu_select_buffer(chan_id, buf_idx);
         dev_dbg(dev, "Updated sg %p on channel 0x%x buffer %d\n",
@@ -1366,10 +1354,11 @@ static irqreturn_t idmac_interrupt(int irq, void *dev_id)
 
         if (likely(sgnew) &&
             ipu_submit_buffer(ichan, descnew, sgnew, ichan->active_buffer) < 0) {
-                callback = desc->txd.callback;
-                callback_param = desc->txd.callback_param;
+                callback = descnew->txd.callback;
+                callback_param = descnew->txd.callback_param;
                 spin_unlock(&ichan->lock);
-                callback(callback_param);
+                if (callback)
+                        callback(callback_param);
                 spin_lock(&ichan->lock);
         }