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

stable inclusion
from stable-5.10.61
commit b353028aed9231214e45dd21274c444870c68dc2
bugzilla: 177029 https://gitee.com/openeuler/kernel/issues/I4EAXD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b353028aed9231214e45dd21274c444870c68dc2

--------------------------------

[ Upstream commit eda97cb0 ]

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: NPeter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20210717190021.21897-1-peter.ujfalusi@gmail.comSigned-off-by: NVinod Koul <vkoul@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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)) {
@@ -79,6 +83,7 @@ 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