linux-kernel - Re: [PATCH 06/14] spi: dt-bindings: dw-apb-ssi: update spi-{r,t}x-bus-width for dwc-ssi

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Date:   Tue, 21 Jun 2022 07:46:28 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Conor.Dooley@...rochip.com, fancer.lancer@...il.com,
        mail@...chuod.ie
Cc:     airlied@...ux.ie, daniel@...ll.ch, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, thierry.reding@...il.com,
        sam@...nborg.org, Eugeniy.Paltsev@...opsys.com, vkoul@...nel.org,
        lgirdwood@...il.com, broonie@...nel.org, daniel.lezcano@...aro.org,
        palmer@...belt.com, palmer@...osinc.com, tglx@...utronix.de,
        paul.walmsley@...ive.com, aou@...s.berkeley.edu,
        masahiroy@...nel.org, geert@...ux-m68k.org, niklas.cassel@....com,
        dillon.minfei@...il.com, jee.heng.sia@...el.com,
        joabreu@...opsys.com, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dmaengine@...r.kernel.org, alsa-devel@...a-project.org,
        linux-spi@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 06/14] spi: dt-bindings: dw-apb-ssi: update
 spi-{r,t}x-bus-width for dwc-ssi

On 6/21/22 06:06, Conor.Dooley@...rochip.com wrote:
> On 20/06/2022 21:56, Serge Semin wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> On Sat, Jun 18, 2022 at 01:30:28PM +0100, Conor Dooley wrote:
>>> From: Conor Dooley <conor.dooley@...rochip.com>
>>>
>>> snps,dwc-ssi-1.01a has a single user - the Canaan k210, which uses a
>>> width of 4 for spi-{r,t}x-bus-width. Update the binding to reflect
>>> this.
>>>
>>> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
>>> ---
>>>  .../bindings/spi/snps,dw-apb-ssi.yaml         | 48 ++++++++++++++-----
>>>  1 file changed, 35 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
>>> index e25d44c218f2..f2b9e3f062cd 100644
>>> --- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
>>> +++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
>>> @@ -135,19 +135,41 @@ properties:
>>>        of the designware controller, and the upper limit is also subject to
>>>        controller configuration.
>>>
>>> -patternProperties:
>>> -  "^.*@[0-9a-f]+$":
>>> -    type: object
>>> -    properties:
>>> -      reg:
>>> -        minimum: 0
>>> -        maximum: 3
>>> -
>>> -      spi-rx-bus-width:
>>> -        const: 1
>>> -
>>> -      spi-tx-bus-width:
>>> -        const: 1
>>> +if:
>>> +  properties:
>>> +    compatible:
>>> +      contains:
>>> +        const: snps,dwc-ssi-1.01a
>>> +
>>> +then:
>>> +  patternProperties:
>>> +    "^.*@[0-9a-f]+$":
>>> +      type: object
>>> +      properties:
>>> +        reg:
>>> +          minimum: 0
>>> +          maximum: 3
>>> +
>>> +        spi-rx-bus-width:
>>> +          const: 4
>>> +
>>> +        spi-tx-bus-width:
>>> +          const: 4
>>> +
>>> +else:
>>> +  patternProperties:
>>> +    "^.*@[0-9a-f]+$":
>>> +      type: object
>>> +      properties:
>>> +        reg:
>>> +          minimum: 0
>>> +          maximum: 3
>>> +
>>> +        spi-rx-bus-width:
>>> +          const: 1
>>> +
>>> +        spi-tx-bus-width:
>>> +          const: 1
>>
>> You can just use a more relaxed constraint "enum: [1 2 4 8]" here
> 
> 8 too? sure.
> 
>> irrespective from the compatible string. The modern DW APB SSI
>> controllers of v.4.* and newer also support the enhanced SPI Modes too
>> (Dual, Quad and Octal). Since the IP-core version is auto-detected at
>> run-time there is no way to create a DT-schema correctly constraining
>> the Rx/Tx SPI bus widths. So let's keep the
>> compatible-string-independent "patternProperties" here but just extend
>> the set of acceptable "spi-rx-bus-width" and "spi-tx-bus-width"
>> properties values.
> 
> SGTM!
> 
>>
>> Note the DW APB SSI/AHB SSI driver currently doesn't support the
>> enhanced SPI modes. So I am not sure whether the multi-lines Rx/Tx SPI
>> bus indeed works for Canaan K210 AHB SSI controller. AFAICS from the
>> DW APB SSI v4.01a manual the Enhanced SPI mode needs to be properly
>> activated by means of the corresponding CSR. So most likely the DW AHB
>> SSI controllers need some specific setups too.
> 
> hmm, well I'll leave that up to people that have Canaan hardware!

I will test this series.

> Thanks,
> Conor.
> 
>>
>> -Sergey
>>
>>>
>>>  unevaluatedProperties: false
>>>
>>> --
>>> 2.36.1
>>>
> 


-- 
Damien Le Moal
Western Digital Research