dmaengine: Make channel allocation callbacks optional

Nowadays, some drivers don't have anything in there channel allocation
callbacks anymore.

Remove the BUG_ON if those callbacks aren't implemented, in order to allow
drivers to not implement them.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index a5da0e147560..b7f09f63a160 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -235,9 +235,11 @@ static int dma_chan_get(struct dma_chan *chan)
                 return -ENODEV;
 
         /* allocate upon first client reference */
-        ret = chan->device->device_alloc_chan_resources(chan);
-        if (ret < 0)
-                goto err_out;
+        if (chan->device->device_alloc_chan_resources) {
+                ret = chan->device->device_alloc_chan_resources(chan);
+                if (ret < 0)
+                        goto err_out;
+        }
 
         if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
                 balance_ref_count(chan);
@@ -259,11 +261,15 @@ err_out:
  */
 static void dma_chan_put(struct dma_chan *chan)
 {
+        /* This channel is not in use, bail out */
         if (!chan->client_count)
-                return; /* this channel failed alloc_chan_resources */
+                return;
+
         chan->client_count--;
         module_put(dma_chan_to_owner(chan));
-        if (chan->client_count == 0)
+
+        /* This channel is not in use anymore, free it */
+        if (!chan->client_count && chan->device->device_free_chan_resources)
                 chan->device->device_free_chan_resources(chan);
 }
 
@@ -818,8 +824,6 @@ int dma_async_device_register(struct dma_device *device)
         BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
                 !device->device_prep_interleaved_dma);
 
-        BUG_ON(!device->device_alloc_chan_resources);
-        BUG_ON(!device->device_free_chan_resources);
         BUG_ON(!device->device_tx_status);
         BUG_ON(!device->device_issue_pending);
         BUG_ON(!device->dev);