On 2021-01-15 17:58, Paul Kocialkowski wrote:
A mechanism was recently introduced for the sunxi architecture where the DMA offset for specific devices (under the MBUS) is set by a common driver (sunxi_mbus). This driver calls dma_direct_set_offset to set the device's dma_range_map manually. However this information was overwritten by of_dma_configure_id, which obtains the map from of_dma_get_range (or keeps it NULL when it fails and the force_dma argument is true, which is the case for platform devices). As a result, the dma_range_map was always overwritten and the mechanism could not correctly take effect. This adds a check to ensure that no previous DMA range map is overwritten and prints a warning when the map was already set while also being available from dt. In this case, the map that was already set is kept.
Hang on, the hard-coded offset is only intended to be installed when there *isn't* anything described in DT, in which case of_dma_get_range() should always bail out early without touching it anyway. This sounds like something's not quite right in the MBUS driver, so I don't think working around it in core code is really the right thing to do.
Do you have a case where one of the relevant devices inherits a "dma-ranges" via the regular hierarchy without indirecting via an "interconnects" reference? Currently you're only checking for the latter, so that would be one way things could go awry (although to be a problem, said "dma-ranges" would also have to encode something *other* than the appropriate MBUS offset, which implies an incorrect or at least inaccurately-structured DT as well).
Robin.
Fixes: b4bdc4fbf8d0 ("soc: sunxi: Deal with the MBUS DMA offsets in a central place") Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> --- drivers/of/device.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/of/device.c b/drivers/of/device.c index aedfaaafd3e7..db1b8634c2c7 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -181,7 +181,14 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,arch_setup_dma_ops(dev, dma_start, size, iommu, coherent); - dev->dma_range_map = map;+ if (!dev->dma_range_map) { + dev->dma_range_map = map; + } else if (map) { + dev_warn(dev, + "DMA range map was already set, ignoring range map from dt\n"); + kfree(map); + } + return 0; } EXPORT_SYMBOL_GPL(of_dma_configure_id);
