[PATCH v2 2/2] of: restricted dma: Don't fail device probe on rmem init failure

Will Deacon
2021-08-16T13:34:21Z

If CONFIG_DMA_RESTRICTED_POOL=n then probing a device with a reference
to a "restricted-dma-pool" will fail with a reasonably cryptic error:

| pci-host-generic: probe of 10000.pci failed with error -22

Rework of_dma_set_restricted_buffer() so that it does not cause probing
failure and instead either returns early if CONFIG_DMA_RESTRICTED_POOL=n
or emits a diagnostic if the reserved DMA pool fails to initialise.

Cc: Claire Chang <tientzu@chromium.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
drivers/of/device.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 089c5b4b97fb..5b043ee30824 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -53,12 +53,15 @@ int of_device_add(struct platform_device *ofdev)
return device_add(&ofdev->dev);
}

-static int
+static void
of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
{
struct device_node *node, *of_node = dev->of_node;
int count, i;

+ if (!IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL))
+ return;
+
count = of_property_count_elems_of_size(of_node, "memory-region",
sizeof(u32));
/*
@@ -79,11 +82,11 @@ of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
*/
if (of_device_is_compatible(node, "restricted-dma-pool") &&
of_device_is_available(node))
- return of_reserved_mem_device_init_by_idx(dev, of_node,
- i);
+ break;
}

- return 0;
+ if (i != count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
+ dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");
}

/**
@@ -200,7 +203,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);

if (!iommu)
- return of_dma_set_restricted_buffer(dev, np);
+ of_dma_set_restricted_buffer(dev, np);

return 0;
}
--
2.33.0.rc1.237.g0d66db33f3-goog