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Date:   Mon, 5 Dec 2022 17:50:18 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Johan Hovold <johan@kernel.org>
Cc:     Johan Hovold <johan+linaro@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        Andy Gross <agross@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Bart Van Assche <bvanassche@acm.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: ufs: qcom: allow 'dma-coherent' property
Message-ID: <20221205122018.GC20192@thinkpad>
References: <20221205100837.29212-1-johan+linaro@kernel.org>
 <20221205100837.29212-2-johan+linaro@kernel.org>
 <20221205115906.GA20192@thinkpad>
 <Y43e9KRDsTCS5VI4@hovoldconsulting.com>
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On Mon, Dec 05, 2022 at 01:07:16PM +0100, Johan Hovold wrote:
> On Mon, Dec 05, 2022 at 05:29:06PM +0530, Manivannan Sadhasivam wrote:
> > On Mon, Dec 05, 2022 at 11:08:36AM +0100, Johan Hovold wrote:
> > > UFS controllers may be cache coherent and must be marked as such in the
> > > devicetree to avoid data corruption.
> > > 
> > > This is specifically needed on recent Qualcomm platforms like SC8280XP.
> > > 
> > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> > > ---
> > >  Documentation/devicetree/bindings/ufs/qcom,ufs.yaml | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/ufs/qcom,ufs.yaml b/Documentation/devicetree/bindings/ufs/qcom,ufs.yaml
> > > index f2d6298d926c..1f1d286749c0 100644
> > > --- a/Documentation/devicetree/bindings/ufs/qcom,ufs.yaml
> > > +++ b/Documentation/devicetree/bindings/ufs/qcom,ufs.yaml
> > > @@ -44,6 +44,8 @@ properties:
> > >      minItems: 8
> > >      maxItems: 11
> > >  
> > > +  dma-coherent: true
> > > +
> > 
> > This property is not applicable to all SoCs. So setting true here will make it
> > valid for all.
> 
> Yes, it would be a valid, but it will only be added to the DTs of SoCs
> that actually require it. No need to re-encode the dtsi in the binding.
> 

But if you make a property valid in the binding then it implies that anyone
could add it to DTS which is wrong. You should make this property valid for
SoCs that actually support it.

Thanks,
Mani

> Johan

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