Re: [PATCH] sdhci-fujitsu: add support for setting the CMD_DAT_DELAY attribute

[Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 2 November 2017 at 01:12, Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> On 2 November 2017 at 00:08, Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>> On Wed, Nov 01, 2017 at 12:21:32AM +0000, Ard Biesheuvel wrote:
>>> The Socionext SynQuacer SoC inherits this IP from Fujitsu, but
>>> requires the F_SDH30_CMD_DAT_DELAY bit to be set in the
>>> F_SDH30_ESD_CONTROL control register.
>>>
>>> So let's add an optional property to this device's binding, and
>>> set the attribute if it is present in the DT node.
>>>
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>>> ---
>>>  Documentation/devicetree/bindings/mmc/sdhci-fujitsu.txt |  2 ++
>>>  drivers/mmc/host/sdhci_f_sdh30.c                        | 18 +++++++++++++++++-
>>>  2 files changed, 19 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-fujitsu.txt b/Documentation/devicetree/bindings/mmc/sdhci-fujitsu.txt
>>> index de2c53cff4f1..9ad02f743ad0 100644
>>> --- a/Documentation/devicetree/bindings/mmc/sdhci-fujitsu.txt
>>> +++ b/Documentation/devicetree/bindings/mmc/sdhci-fujitsu.txt
>>> @@ -15,6 +15,8 @@ Required properties:
>>>  Optional properties:
>>>  - vqmmc-supply: phandle to the regulator device tree node, mentioned
>>>    as the VCCQ/VDD_IO supply in the eMMC/SD specs.
>>> +- cmd-dat-delay-select: boolean property indicating that this host requires
>>> +  the CMD_DAT_DELAY control to be enabled.
>>
>> Needs a vendor prefix unless this is a standard SDHCI bit (in which
>> case it should be documented in a common spot).
>>
>
> I suspect this is a non-standard thing, so I'll add the fujitsu prefix. Ulf?

This is specific to the Fujitsu variant.

However, what puzzles me is why this bit is needed for the Socionext
SynQuacer SoC, but not for other SoCs that uses this IP. That seems
weird (probably wrong).

Moreover, the F_SDH30_CMD_DAT_DELAY register define is already there,
so I would rather suspect that it's something that did got fully
implemented. In other words, I don't think you need a new DT binding,
but rather try to implement it generically for the sdhci-f_sdh30
driver. Do you think that will work?

Kind regards
Uffe
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