# Re: \[PATCH 02/11\] dt-bindings: serial: snps-dw-apb-uart: Relax dma-names order constraint

- From: Krzysztof Kozlowski \<hidden\>
- Date: 2023-03-17 15:54:57 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2023/03/2138154
- Thread: https://ratatoskr.run/linux-arm-kernel/2023/03/2134727/t.md

```text
On 17/03/2023 11:21, Cristian Ciocaltea wrote:
> On 3/17/23 10:31, Krzysztof Kozlowski wrote:
>> On 15/03/2023 12:47, Cristian Ciocaltea wrote:
>>> Commit 370f696e4474 ("dt-bindings: serial: snps-dw-apb-uart: add dma &
>>> dma-names properties") documented dma-names property to handle Allwiner
>>> D1 dtbs_check warnings, but relies on a strict rx->tx ordering, which is
>>> the reverse of what a different board expects:
>>>
>>>    rk3326-odroid-go2.dtb: serial@ff030000: dma-names:0: 'rx' was expected
>>>
>>> A quick and incomplete check shows the inconsistency is present in many
>>> other DT files:
>>
>> Why not fixing the DTS? The properties should have fixed order.
> 
> I was initially concerned about the risk of a potential ABI breakage, 
> but I think that's not really a problem since dma-names is not directly 
> accessed in the driver and DT Kernel API doesn't rely on a particular order.
> 
> If there are no objections, I would switch the order in the binding to 
> tx->rx, since that's what most of the DTS use, and fix the remaining ones.

Since we added the order recently, I rather assume it is the correct or
preferred one.

Best regards,
Krzysztof


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