dmaengine: advertise all channels on a device to dma_filter_fn

Allow dma_filter_fn routines to disambiguate multiple channels on a device
rather than assuming that all channels on a device are equal.

Cc: Maciej Sosnowski <maciej.sosnowski@intel.com>
Reported-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 13 insertions, 20 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index dd43410c1019..9d3594cf17e0 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -454,10 +454,10 @@ static void dma_channel_rebalance(void)
                 }
 }
 
-static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev)
+static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev,
+                                          dma_filter_fn fn, void *fn_param)
 {
         struct dma_chan *chan;
-        struct dma_chan *ret = NULL;
 
         if (!__dma_device_satisfies_mask(dev, mask)) {
                 pr_debug("%s: wrong capabilities\n", __func__);
@@ -479,11 +479,15 @@ static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_devic
                                  __func__, dma_chan_name(chan));
                         continue;
                 }
-                ret = chan;
-                break;
+                if (fn && !fn(chan, fn_param)) {
+                        pr_debug("%s: %s filter said false\n",
+                                 __func__, dma_chan_name(chan));
+                        continue;
+                }
+                return chan;
         }
 
-        return ret;
+        return NULL;
 }
 
 /**
@@ -496,22 +500,13 @@ struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, v
 {
         struct dma_device *device, *_d;
         struct dma_chan *chan = NULL;
-        bool ack;
         int err;
 
         /* Find a channel */
         mutex_lock(&dma_list_mutex);
         list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
-                chan = private_candidate(mask, device);
-                if (!chan)
-                        continue;
-
-                if (fn)
-                        ack = fn(chan, fn_param);
-                else
-                        ack = true;
-
-                if (ack) {
+                chan = private_candidate(mask, device, fn, fn_param);
+                if (chan) {
                         /* Found a suitable channel, try to grab, prep, and
                          * return it.  We first set DMA_PRIVATE to disable
                          * balance_ref_count as this channel will not be
@@ -529,10 +524,8 @@ struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, v
                                        dma_chan_name(chan), err);
                         else
                                 break;
-                } else
-                        pr_debug("%s: %s filter said false\n",
-                                 __func__, dma_chan_name(chan));
-                chan = NULL;
+                        chan = NULL;
+                }
         }
         mutex_unlock(&dma_list_mutex);