Re: [PATCH v2 2/3] dt-bindings: mmc: Add a new property disable-cqe-dcmd.

Christoph Müllner
2019-03-08T13:10:45Z

> On 08.03.2019, at 13:46, Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 7/03/19 10:43 AM, Christoph Muellner wrote:
>> This patch documents the new property disable-cqe-dcmd
>> for the Arasan eMMC 5.1 driver.
>>
>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> ---
>> Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> index 1edbb049cccb..ec699bf98b7c 100644
>> --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> @@ -44,6 +44,10 @@ Optional Properties:
>> properly. Test mode can be used to force the controller to function.
>> - xlnx,int-clock-stable-broken: when present, the controller always reports
>> that the internal clock is stable even when it is not.
>> + - disable-cqe-dcmd: The eMMC 5.1 standard specifies direct commands (DCMDs)
>> + as part of the command queue engine (CQE). On controllers with a CQHCI,
>> + such as the Arasan eMMC 5.1 host controller, the driver has to enable DCMDs.
>> + This is done unless disable-cqe-dcmd is specified.
>
> If "supports-cqe" is in mmc.txt, should "disable-cqe-dcmd" be there also?

The file mmc.txt says on top:
"These properties are common to multiple MMC host controllers".
As my patchset introduces "disable-cqe-dcmd" just for sdhci-of-arasan,
I would say it should not go into that file.

Also I wonder why "supports-cqe" is in mmc.txt, because
only sdhci-tegra.c is evaluating that property.
So I would expect it to be documented in
Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt

However, I see that "disable-cqe-dcmd" could go into other drivers as well.
But is this enough to document it in mmc.txt?