Now that we can track upstream DMA constraints properly with
bus_dma_mask instead of trying (and failing) to maintain it in
coherent_dma_mask, it doesn't make much sense for the firmware code to
be touching the latter at all. It's merely papering over bugs wherein a
driver has failed to call dma_set_coherent_mask() *and* the bus code has
not initialised any default value.
We don't really want to encourage more drivers coercing dma_mask so
we'll continue to fix that up if necessary, but add a warning to help
flush out any such buggy bus code that remains.
CC: Rob Herring <robh+dt@xxxxxxxxxx>
CC: Frank Rowand <frowand.list@xxxxxxxxx>
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
drivers/of/device.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 0d39633e8545..5957cd4fa262 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -127,20 +127,20 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
}
/*
- * Set default coherent_dma_mask to 32 bit. Drivers are expected to
- * setup the correct supported mask.
+ * If @dev is expected to be DMA-capable then the bus code that created
+ * it should have initialised its dma_mask pointer by this point. For
+ * now, we'll continue the legacy behaviour of coercing it to the
+ * coherent mask if not, but we'll no longer do so quietly.
*/
- if (!dev->coherent_dma_mask)
- dev->coherent_dma_mask = DMA_BIT_MASK(32);
- /*
- * Set it to coherent_dma_mask by default if the architecture
- * code has not set it.
- */
- if (!dev->dma_mask)
+ if (!dev->dma_mask) {
+ dev_warn(dev, "DMA mask not set\n");
dev->dma_mask = &dev->coherent_dma_mask;
+ }
- if (!size)
+ if (!size && dev->coherent_dma_mask)
size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
+ else if (!size)
+ size = 1ULL << 32;
dev->dma_pfn_offset = offset;
--
2.17.1.dirty
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