Re: [PATCH v2] of/device: Update dma_range_map only when dev has valid dma-ranges

Robin Murphy
2021-01-27T19:34:39Z

On 2021-01-27 19:07, Rob Herring wrote:
> On Tue, Jan 19, 2021 at 4:52 AM Yong Wu <yong.wu@mediatek.com> wrote:
>>
>> The commit e0d072782c73 ("dma-mapping: introduce DMA range map,
>> supplanting dma_pfn_offset") always update dma_range_map even though it was
>> already set, like in the sunxi_mbus driver. the issue is reported at [1].
>> This patch avoid this(Updating it only when dev has valid dma-ranges).
>
> only when dev *doesn't* have valid dma-ranges?

I believe the intent is to mean when a valid "dma-ranges" property is
specified in DT. The implementation allows DT to take precedence even if
platform code *has* already installed a dma_range_map, although we
shouldn't expect that to ever happen (except perhaps in the wild early
days of platform bringup).

Robin.

>> Meanwhile, dma_range_map contains the devices' dma_ranges information,
>> This patch moves dma_range_map before of_iommu_configure. The iommu
>> driver may need to know the dma_address requirements of its iommu
>> consumer devices.
>>
>> [1] https://lore.kernel.org/linux-arm-kernel/5c7946f3-b56e-da00-a750-be097c7ceb32@arm.com/
>>
>> CC: Rob Herring <robh+dt@kernel.org>
>> CC: Frank Rowand <frowand.list@gmail.com>
>> Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset"),
>> Suggested-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
>> Reviewed-by: Rob Herring <robh@kernel.org>
>> ---
>> drivers/of/device.c | 10 +++++++---
>> 1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index aedfaaafd3e7..1122daa8e273 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -162,9 +162,11 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>> mask = DMA_BIT_MASK(ilog2(end) + 1);
>> dev->coherent_dma_mask &= mask;
>> *dev->dma_mask &= mask;
>> - /* ...but only set bus limit if we found valid dma-ranges earlier */
>> - if (!ret)
>> + /* ...but only set bus limit and range map if we found valid dma-ranges earlier */
>> + if (!ret) {
>> dev->bus_dma_limit = end;
>> + dev->dma_range_map = map;
>> + }
>>
>> coherent = of_dma_is_coherent(np);
>> dev_dbg(dev, "device is%sdma coherent\n",
>> @@ -172,6 +174,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>>
>> iommu = of_iommu_configure(dev, np, id);
>> if (PTR_ERR(iommu) == -EPROBE_DEFER) {
>> + /* Don't touch range map if it wasn't set from a valid dma-ranges */
>> + if (!ret)
>> + dev->dma_range_map = NULL;
>> kfree(map);
>> return -EPROBE_DEFER;
>> }
>> @@ -181,7 +186,6 @@ 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;
>> return 0;
>> }
>> EXPORT_SYMBOL_GPL(of_dma_configure_id);
>> --
>> 2.18.0
>>
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