Merge branch 'topic/defer_probe' into for-linus

2 files changed, 40 insertions, 10 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ea806bdc12ef..e17e9b22d85e 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -540,6 +540,8 @@ EXPORT_SYMBOL_GPL(dma_get_slave_channel);
  * @mask: capabilities that the channel must satisfy
  * @fn: optional callback to disposition available channels
  * @fn_param: opaque parameter to pass to dma_filter_fn
+ *
+ * Returns pointer to appropriate DMA channel on success or NULL.
  */
 struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
                                        dma_filter_fn fn, void *fn_param)
@@ -591,18 +593,43 @@ EXPORT_SYMBOL_GPL(__dma_request_channel);
  * dma_request_slave_channel - try to allocate an exclusive slave channel
  * @dev:        pointer to client device structure
  * @name:       slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
  */
-struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name)
+struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
+                                                  const char *name)
 {
+        struct dma_chan *chan;
+
         /* If device-tree is present get slave info from here */
         if (dev->of_node)
                 return of_dma_request_slave_channel(dev->of_node, name);
 
         /* If device was enumerated by ACPI get slave info from here */
-        if (ACPI_HANDLE(dev))
-                return acpi_dma_request_slave_chan_by_name(dev, name);
+        if (ACPI_HANDLE(dev)) {
+                chan = acpi_dma_request_slave_chan_by_name(dev, name);
+                if (chan)
+                        return chan;
+        }
 
-        return NULL;
+        return ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(dma_request_slave_channel_reason);
+
+/**
+ * dma_request_slave_channel - try to allocate an exclusive slave channel
+ * @dev:        pointer to client device structure
+ * @name:       slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or NULL.
+ */
+struct dma_chan *dma_request_slave_channel(struct device *dev,
+                                           const char *name)
+{
+        struct dma_chan *ch = dma_request_slave_channel_reason(dev, name);
+        if (IS_ERR(ch))
+                return NULL;
+        return ch;
 }
 EXPORT_SYMBOL_GPL(dma_request_slave_channel);
 
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 0b88dd3d05f4..e8fe9dc455f4 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -143,7 +143,7 @@ static int of_dma_match_channel(struct device_node *np, const char *name,
  * @np:         device node to get DMA request from
  * @name:       name of desired channel
  *
- * Returns pointer to appropriate dma channel on success or NULL on error.
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
  */
 struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
                                               const char *name)
@@ -152,17 +152,18 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
         struct of_dma           *ofdma;
         struct dma_chan         *chan;
         int                     count, i;
+        int                     ret_no_channel = -ENODEV;
 
         if (!np || !name) {
                 pr_err("%s: not enough information provided\n", __func__);
-                return NULL;
+                return ERR_PTR(-ENODEV);
         }
 
         count = of_property_count_strings(np, "dma-names");
         if (count < 0) {
                 pr_err("%s: dma-names property of node '%s' missing or empty\n",
                         __func__, np->full_name);
-                return NULL;
+                return ERR_PTR(-ENODEV);
         }
 
         for (i = 0; i < count; i++) {
@@ -172,10 +173,12 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
                 mutex_lock(&of_dma_lock);
                 ofdma = of_dma_find_controller(&dma_spec);
 
-                if (ofdma)
+                if (ofdma) {
                         chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
-                else
+                } else {
+                        ret_no_channel = -EPROBE_DEFER;
                         chan = NULL;
+                }
 
                 mutex_unlock(&of_dma_lock);
 
@@ -185,7 +188,7 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
                         return chan;
         }
 
-        return NULL;
+        return ERR_PTR(ret_no_channel);
 }
 
 /**