[PATCH v2 7/7] OF: Don't set default coherent DMA mask
From: robin.murphy@arm.com (Robin Murphy)
Date: 2018-07-23 22:16:12
Also in:
linux-acpi, linux-iommu
Subsystem:
open firmware and flattened device tree, the rest · Maintainers:
Rob Herring, Saravana Kannan, Linus Torvalds
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@kernel.org> CC: Frank Rowand <redacted> Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- 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