On 07/23/2018 05:16 PM, Robin Murphy wrote:
quoted hunk ↗ jump to hunk
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 <redacted>
CC: Frank Rowand <redacted>
Signed-off-by: Robin Murphy <redacted>
---
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;
the result of this change is pretty strange as for me :(
Resulted code:
/*
* 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->dma_mask) {
dev_warn(dev, "DMA mask not set\n");
dev->dma_mask = &dev->coherent_dma_mask;
^this will always produce warning in case of platform-bus or if there are no bus driver.
even if DT contains correct definition of dma-range
}
if (!size && dev->coherent_dma_mask)
^ coherent_dma_mask is zero, so size will not be calculated
size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
else if (!size)
size = 1ULL << 32;
dev->dma_pfn_offset = offset;
/*
* Limit coherent and dma mask based on size and default mask
* set by the driver.
*/
mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
dev->bus_dma_mask = mask;
dev->coherent_dma_mask &= mask;
^^ if nobody set coherent_dma_mask before it will stay null forever unless drivers
will overwrite it. Again even if DT has correct definition for dma-range.
*dev->dma_mask &= mask;
coherent = of_dma_is_coherent(np);
dev_dbg(dev, "device is%sdma coherent\n",
coherent ? " " : " not ");
--
regards,
-grygorii