Re: [PATCH 1/2] dt-bindings: mmc: dw-mshc-common: add option for configuring DMA threshold

[Kaustabh Chakraborty]

On 2026-04-12 09:59 +05:30, Kaustabh Chakraborty wrote:
> On 2026-04-11 22:27 +02:00, Krzysztof Kozlowski wrote:
>> On 11/04/2026 21:43, Kaustabh Chakraborty wrote:
>>> Some controllers, such as certain Exynos SDIO ones, are unable to
>>> perform DMA transfers of small amount of bytes properly. Add a property
>>> to configure the DMA transfer threshold.
>>> 
>>> Signed-off-by: Kaustabh Chakraborty <kauschluss@xxxxxxxxxxx>
>>> ---
>>>  .../devicetree/bindings/mmc/synopsys-dw-mshc-common.yaml          | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>> 
>>> diff --git a/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc-common.yaml b/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc-common.yaml
>>> index 6f11b2adf1036..1693277957a91 100644
>>> --- a/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc-common.yaml
>>> +++ b/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc-common.yaml
>>> @@ -57,6 +57,14 @@ properties:
>>>        force fifo watermark setting accordingly.
>>>      $ref: /schemas/types.yaml#/definitions/flag
>>>  
>>> +  dma-threshold-bytes:
>>> +    description:
>>> +      DMA transfer takes place only if the transfer size is equal to or greater
>>> +      than the number of bytes defined by the threshold value. Some controllers are
>>> +      unable to perform the DMA transfer properly with small amounts of data.
>>
>> Looks like controller specific, thus should be deducible from the
>> compatible.
>
> "samsung,dma-threshold-bytes"? So you also suggest I move it to the
> Samsung's schema? Okay.

Ahh, nevermind I get it. A separate controller compatible which sets a
higher threshold.

>
>>
>> Best regards,
>> Krzysztof