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: Lorenzo Pieralisi <redacted>
CC: Hanjun Guo <redacted>
CC: Sudeep Holla <redacted>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/acpi/arm64/iort.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index bc51cff5505e..08f26db2da7e 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -978,20 +978,20 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
int ret, msb;
/*
- * 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;
+ }
- size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
+ if (dev->coherent_dma_mask)
+ size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
+ else
+ size = 1ULL << 32;
if (dev_is_pci(dev)) {
ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);--
2.17.1.dirty