Message-ID: <5d3802bc-68e8-43a8-8dfa-14d5b2b9e624@kernel.org>
Date: Sat, 6 Sep 2025 10:55:10 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Charan Pedumuru <charan.pedumuru@...il.com>,
 Ulf Hansson <ulf.hansson@...aro.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: mmc: sdhci-omap: convert text based binding
 to json schema

On 06/09/2025 10:43, Charan Pedumuru wrote:
> 
> 
> On 28-05-2025 13:30, Krzysztof Kozlowski wrote:
>> On 23/05/2025 19:05, Charan Pedumuru wrote:
>>> Convert TI OMAP SDHCI Controller binding to YAML format.
>>> Changes during Conversion:
>>> - Add patternProperties for pinctrl-<n>.
>>> - Define new properties like "ti,hwmods", "ti,needs-special-reset"
>>>   "ti,needs-special-hs-handling", "cap-mmc-dual-data-rate"
>>>   and "pbias-supply".
>>
>> Why? commit should answer this.
> 
> The above properties are not documented in the text binding, so I defined them to resolve DTB_CHECK, I will write the reason in next revision.

You revive discussion from 3 months ago...

Anyway, explain in the commit msg that properties are already used in
the DTS.

> 
>>
>>> - Remove "ti,hwmods", "pinctrl-names" and "pinctrl-<n>"
>>
>> Why? You just added ti,hwmods, so how can you remove it from required?
> 
> The property is defined but is not required by all DTS files and the old binding says it is required for all boards, I will add this reason to the commit message.
> 
>>
>>>   from required as they are not necessary for all DTS files.
>>> - Add missing strings like "default-rev11", "sdr12-rev11", "sdr25-rev11",
>>>   "hs-rev11", "sdr25-rev11" and "sleep" to pinctrl-names string array.
>>>
>>> Signed-off-by: Charan Pedumuru <charan.pedumuru@...il.com>
>>> ---
>>>  .../devicetree/bindings/mmc/sdhci-omap.txt         |  43 ------
>>>  .../devicetree/bindings/mmc/sdhci-omap.yaml        | 155 +++++++++++++++++++++
>>
>>
>> Filename: ti,omap-sdhci.yaml or one of the compatibles (or anything else
>> following convention that it should match compatible).
> 
> Sure, I was following the name format of other files from the same directory here, but will change it to the compatible in next revision.
> 
>>
>>
>> "ti,needs-special-hs-handling" is already documented in other binding
> 
> Well, I didn't see this property defined in any common.yaml in mmc directory.
> 
>>
>>
>>>  2 files changed, 155 insertions(+), 43 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-omap.txt b/Documentation/devicetree/bindings/mmc/sdhci-omap.txt
>>> deleted file mode 100644
>>> index f91e341e6b36c410275e6f993dd08400be3fc1f8..0000000000000000000000000000000000000000
>>> --- a/Documentation/devicetree/bindings/mmc/sdhci-omap.txt
>>> +++ /dev/null
>>> @@ -1,43 +0,0 @@
>>> -* TI OMAP SDHCI Controller
>>
>>
>> ...
>>
>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-omap.yaml b/Documentation/devicetree/bindings/mmc/sdhci-omap.yaml
>>> new file mode 100644
>>> index 0000000000000000000000000000000000000000..e707837bc242b055bbc497ed893a91c9b24f2dde
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mmc/sdhci-omap.yaml
>>> @@ -0,0 +1,155 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/mmc/sdhci-omap.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: TI OMAP SDHCI Controller
>>> +
>>> +maintainers:
>>> +  - Ulf Hansson <ulf.hansson@...aro.org>
>>
>> This is supposed to be someone caring about this device. Eventually
>> platform maintainer.
> 
> Sure, I will change that, I was following the names of MAINTAINERS from the list I got from the command, "./scripts/get_maintainer.pl Documentation/dev
> icetree/bindings/mmc/sdhci-omap.txt"
> 
>>
>>> +
>>> +description:
>>> +  For UHS devices which require tuning, the device tree should have a
>>> +  cpu_thermal node which maps to the appropriate thermal zone. This
>>> +  is used to get the temperature of the zone during tuning.
>>> +
>>> +allOf:
>>> +  - $ref: sdhci-common.yaml#
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - ti,omap2430-sdhci
>>> +      - ti,omap3-sdhci
>>> +      - ti,omap4-sdhci
>>> +      - ti,omap5-sdhci
>>> +      - ti,dra7-sdhci
>>> +      - ti,k2g-sdhci
>>> +      - ti,am335-sdhci
>>> +      - ti,am437-sdhci
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>> +
>>> +  pinctrl-names:
>>> +    $ref: /schemas/types.yaml#/definitions/string-array
>>> +    minItems: 1
>>> +    maxItems: 19
>>> +    items:
>>> +      enum:
>>> +        - default
>>> +        - default-rev11
>>> +        - hs
>>> +        - sdr12
>>> +        - sdr12-rev11
>>> +        - sdr25
>>> +        - sdr25-rev11
>>> +        - sdr50
>>> +        - ddr50-rev11
>>> +        - sdr104-rev11
>>> +        - ddr50
>>> +        - sdr104
>>> +        - ddr_1_8v-rev11
>>> +        - ddr_1_8v
>>> +        - ddr_3_3v
>>> +        - hs-rev11
>>> +        - hs200_1_8v-rev11
>>> +        - hs200_1_8v
>>> +        - sleep
>>> +
>>> +  dmas:
>>> +    maxItems: 2
>>> +
>>> +  dma-names:
>>> +    items:
>>> +      - const: tx
>>> +      - const: rx
>>> +
>>> +  ti,hwmods:
>>> +    $ref: /schemas/types.yaml#/definitions/string
>>> +    description:
>>> +      This field is used to fetch the information such as
>>> +      address range, irq lines, dma lines, interconnect, PRCM register,
>>> +      clock domain, input clocks associated with MMC.
>>> +    pattern: "^mmc[0-9]+$"
>>> +
>>> +  ti,needs-special-reset:
>>
>> I don't understand why you added this. There is no user of it.
> 
> 
> May be, but the DTB_CHECK failed for some boards when not defined it here.

Then maybe should be dropped from DTS?

> 
>>
>>> +    description:
>>> +      It indicates that a specific soft reset sequence is required for
>>> +      certain Texas Instruments devices, particularly those with
>>> +      HSMMC (High-Speed MultiMediaCard) controllers.
>>> +    type: boolean
>>> +
>>> +  ti,needs-special-hs-handling:
>>
>> I don't understand why you added this. There is no user of it.
> 
> ...
> 
>>
>>
>>> +    description:
>>> +      It's presence in an MMC controller's DT node signals to the Linux kernel's
>>> +      omap_hsmmc driver that this particular IP block requires special software
>>> +      handling or workarounds to correctly manage High-Speed (HS) modes like
>>> +      SDR25, SDR50, SDR104, DDR50.
>>> +    type: boolean
>>> +
>>> +  pbias-supply:
>>> +    description:
>>> +      It is used to specify the voltage regulator that provides the bias
>>> +      voltage for certain analog or I/O pads.
>>> +
>>> +  cap-mmc-dual-data-rate:
>>> +    description:
>>> +      A characteristic or capability associated with MultiMediaCard (MMC)
>>> +      interfaces, specifically indicating that the MMC controller
>>> +      supports Dual Data Rate (DDR) mode
>>
>> Drop the property. We have standard properties for this and there is no
>> ABI for it anyway.
>>
> 
> Same here, the DTB_CHECK failed, so had to define it here
> 
>>> +    type: boolean
>>> +
>>> +  ti,non-removable:
>>> +    description:
>>> +      It indicates that a component is not meant to be easily removed or
>>> +      replaced by the user, such as an embedded battery or a non-removable
>>> +      storage slot like eMMC.
>>> +    type: boolean
>>> +    deprecated: true
>>> +
>>> +  vmmmc-supply:
>>> +    description:
>>> +      It is used to specify the power supply (regulator) for the MMC/SD card's
>>> +      main operating voltage (VCC/VDD).
>>> +
>>> +  clock-frequency:
>>
>> Why is it here? Nothing in commit msg explained adding it.
> 
> I will add this change to commit message along with the reason.
> 
>>
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    description:
>>> +      It is used to specify the frequency of a clock in Hertz (Hz). It's a
>>> +      fundamental property for communicating hardware clocking information from
>>> +      the Device Tree to the Linux kernel.
>>
>> Redundant description. It is not a fundamental property. It is a legacy
>> property.
>>
> 
> Sure, will change the description.
> 
>>> +
>>> +patternProperties:
>>> +  "^pinctrl-[0-9]+$":
>>> +    $ref: /schemas/types.yaml#/definitions/phandle-array
>>> +    description:
>>> +      Phandles to pinctrl states. The numeric suffix determines the
>>> +      state index corresponding to entries in the pinctrl-names array.
>>> +    minItems: 1
>>
>> Why exactly do you need these?
> 
> Some boards have this property with multiple pincontrol states, so had to define a pattern property to recognize all the defined pinctrl properties.

No, that's just confusing error from dtschema. Look at other bindings -
no binding defines type and description for pinctrl.

It just means your schema was incomplete.

Best regards,
Krzysztof

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