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>

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index dd43410c10193e920f1adfbcf96257b0c0502c50..9d3594cf17e07df025e26a248ebc3ed92a99e430 100644 (file)
--- 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);