OF: Don't set default coherent DMA mask (4d8bde88) · Commits · 戴 / test

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. Signed-off-by:

Robin Murphy <robin.murphy@arm.com> Acked-by:

Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by:

Christoph Hellwig <hch@lst.de>

drivers/of/device.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -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;

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