Commit c863d953 authored Jul 17, 2021 by Peter Ujfalusi Committed by Sasha Levin Aug 26, 2021

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



[ 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>

parent 32e6ea21

drivers/dma/of-dma.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -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