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SubjectRe: [PATCH 3/5] dt-bindings: mmc: sdhci-cadence: SD6 support
Hi Krzysztof,

On Sat, Jan 07, 2023 at 02:25:02PM +0100, Krzysztof Kozlowski wrote:
> On 06/01/2023 17:48, Piyush Malgujar wrote:
> > Hi Krzysztof,
> >
> > Thank you the review comments.
> >
> > On Mon, Dec 19, 2022 at 04:40:35PM +0100, Krzysztof Kozlowski wrote:
> >> On 19/12/2022 15:24, Piyush Malgujar wrote:
> >>> From: Jayanthi Annadurai <jannadurai@marvell.com>
> >>>
> >>
> >> Subject: use final prefix matching the file, so "cdns,sdhci:"
> >>
> >>> Add support for SD6 controller support
> >>
> >> Full stop.
> >>
> >>>
> >>> Signed-off-by: Jayanthi Annadurai <jannadurai@marvell.com>
> >>> Signed-off-by: Piyush Malgujar <pmalgujar@marvell.com>
> >>> ---
> >>> .../devicetree/bindings/mmc/cdns,sdhci.yaml | 33 +++++++++++++++++--
> >>> 1 file changed, 31 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml b/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
> >>> index 8b1a0fdcb5e3e2e8b87d8d7678e37f3dad447fc1..2043e78ccd5f708a01e87fd96ec410418fcd539f 100644
> >>> --- a/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
> >>> +++ b/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
> >>> @@ -4,7 +4,7 @@
> >>> $id: http://devicetree.org/schemas/mmc/cdns,sdhci.yaml#
> >>> $schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>
> >>> -title: Cadence SD/SDIO/eMMC Host Controller (SD4HC)
> >>> +title: Cadence SD/SDIO/eMMC Host Controller (SD4HC, SD6HC)
> >>>
> >>> maintainers:
> >>> - Masahiro Yamada <yamada.masahiro@socionext.com>
> >>> @@ -19,6 +19,7 @@ properties:
> >>> - microchip,mpfs-sd4hc
> >>> - socionext,uniphier-sd4hc
> >>> - const: cdns,sd4hc
> >>> + - const: cdns,sd6hc
> >>
> >> Does not look like you tested the DTS against bindings. Please run `make
> >> dtbs_check` (see Documentation/devicetree/bindings/writing-schema.rst
> >> for instructions).
> >>
> >> ... because it does not really make sense. Why do you require SD6HC as
> >> fallback? I think you meant enum.
> >>
> >
> > Yes, that's correct. I will change it to enum.
> >
> >>>
> >>> reg:
> >>> maxItems: 1
> >>> @@ -111,6 +112,34 @@ properties:
> >>> minimum: 0
> >>> maximum: 0x7f
> >>>
> >>> + cdns,iocell_input_delay:
> >>
> >> No underscores. Use proper units in name suffix:
> >> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
> >>
> >>
> >>> + description: Delay in ps across the input IO cells
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>
> >> Ditto... and so on - all of the fields.
> >>
> >>> +
> >>> + cdns,iocell_output_delay:
> >>> + description: Delay in ps across the output IO cells
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>> +
> >>> + cdns,delay_element:
> >>> + description: Delay element in ps used for calculating phy timings
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>> +
> >>> + cdns,read_dqs_cmd_delay:
> >>> + description: Command delay used in HS200 tuning
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>> +
> >>> + cdns,tune_val_start:
> >>> + description: Staring value of data delay used in HS200 tuning
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>> +
> >>> + cdns,tune_val_step:
> >>> + description: Incremental value of data delay used in HS200 tuning
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>> +
> >>> + cdns,max_tune_iter:
> >>> + description: Maximum number of iterations to complete the HS200 tuning process
> >>> + $ref: "/schemas/types.yaml#/definitions/uint32"
> >>
> >> Why these three are properties of DT?
> >>
> >
> > These tuning parameters are added here so to make them custom configurable for different
> > boards.
>
> I understand why do you wanted to add them, but I am asking why these
> are suitable for DT? DT describes hardware, so what is here specific to
> hardware which requires DT property?
>
>

We have different values based on emmc devices populated on different boards and these
tuning parameters are used to program phy registers accordingly.

> Best regards,
> Krzysztof

Thanks,
Piyush>

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