dmaengine: of-dma: router_xlate to return -EPROBE_DEFER if controller is not yet...

If the router_xlate can not find the controller in the available DMA
devices then it should return with -EPORBE_DEFER in a same way as the
of_dma_request_slave_channel() does.

The issue can be reproduced if the event router is registered before the
DMA controller itself and a driver would request for a channel before the
controller is registered.
In of_dma_request_slave_channel():
1. of_dma_find_controller() would find the dma_router
2. ofdma->of_dma_xlate() would fail and returned NULL
3. -ENODEV is returned as error code

with this patch we would return in this case the correct -EPROBE_DEFER and
the client can try to request the channel later.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20210717190021.21897-1-peter.ujfalusi@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index ec00b20..ac61ecd 100644 (file)
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -67,8 +67,12 @@ static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
                return NULL;
 
        ofdma_target = of_dma_find_controller(&dma_spec_target);
-       if (!ofdma_target)
-               return NULL;
+       if (!ofdma_target) {
+               ofdma->dma_router->route_free(ofdma->dma_router->dev,
+                                             route_data);
+               chan = ERR_PTR(-EPROBE_DEFER);
+               goto err;
+       }
 
        chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
        if (IS_ERR_OR_NULL(chan)) {
@@ -89,6 +93,7 @@ static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
                }
        }
 
+err:
        /*
         * Need to put the node back since the ofdma->of_dma_route_allocate
         * has taken it for generating the new, translated dma_spec