linux-kernel - Re: [PATCH 1/2] dt-bindings: misc: qcom,fastrpc: add qcom,assign-all-memory property

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Date:   Mon, 27 Mar 2023 13:37:03 +0200
From:   Dylan Van Assche <me@...anvanassche.be>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: misc: qcom,fastrpc: add
 qcom,assign-all-memory property

Hi Krzysztof,

On Sun, 2023-03-26 at 10:55 +0200, Krzysztof Kozlowski wrote:
> On 25/03/2023 14:44, Dylan Van Assche wrote:
> > Document the added qcom,assign-all-memory in devicetree bindings.
> > 
> > Signed-off-by: Dylan Van Assche <me@...anvanassche.be>
> > ---
> >  Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml | 6
> > ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
> > b/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
> > index 1ab9588cdd89..fa5b00534b30 100644
> > --- a/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
> > +++ b/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
> > @@ -57,6 +57,12 @@ properties:
> >        Virtual machine IDs for remote processor.
> >      $ref: "/schemas/types.yaml#/definitions/uint32-array"
> >  
> > +  qcom,assign-all-mem:
> > +    description:
> > +      Assign memory to all Virtual machines defined by qcom,vmids.
> 
> This (neither commit msg) does not explain why this is needed and
> actually does not sound like hardware-related property.

This is made a separate property to toggle different behavior in the
driver if it is needed for some FastRPC nodes. Downstream does guard
this with a property 'restrict-access' as well, see [1] for a random
SDM845 downstream kernel. On SDM845, this property is not present, thus
the IF block runs. On SDM670, this property is present, then the IF
block is skipped. That's why I opt for this property to have this
behaviour conditionally. I'm not sure how to explain it better though.

Any feedback is appreciated, thanks!

Kind regards,
Dylan Van Assche

[1]
https://github.com/SHIFTPHONES/android_kernel_shift_sdm845/blob/sos-3.x/drivers/char/adsprpc.c#L4615-L4631

> 
> > +    type: boolean
> > +
> > +
> 
> Do not add double blank lines.
> 
> >    "#address-cells":
> >      const: 1
> >  
> 
> Best regards,
> Krzysztof
>