From: Peter Ujfalusi peter.ujfalusi@gmail.com
[ Upstream commit eda97cb095f2958bbad55684a6ca3e7d7af0176a ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/of-dma.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c index 757cf48c1c5e..441f37b41abd 100644 --- a/drivers/dma/of-dma.c +++ b/drivers/dma/of-dma.c @@ -68,8 +68,12 @@ 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)) { @@ -80,6 +84,7 @@ static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec, chan->route_data = route_data; }
+err: /* * Need to put the node back since the ofdma->of_dma_route_allocate * has taken it for generating the new, translated dma_spec