linux-kernel - Re: [PATCH v2 16/17] crypto: qce: Defer probe in case interconnect is not yet initialized

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Date:   Tue, 18 May 2021 20:09:37 +0530
From:   Bhupesh Sharma <bhupesh.sharma@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-crypto@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        bhupesh.linux@...il.com
Subject: Re: [PATCH v2 16/17] crypto: qce: Defer probe in case interconnect is
 not yet initialized

Hi Thara,

On Mon, 10 May 2021 at 18:53, Thara Gopinath <thara.gopinath@...aro.org> wrote:
>
>
>
> On 5/5/21 5:37 PM, Bhupesh Sharma wrote:
> > On some Qualcomm parts the qce crypto driver needs the interconnect between
> > the crypto block and main memory to be initialized first before the crypto
> > registers can be accessed. So it makes sense to defer the qce crypto driver
> > probing in case the interconnect driver is not yet probed.
> >
> > This fixes the qce probe failure issues when both qce and
> > interconnect drivers are compiled as static part of the kernel.
> >
> > Cc: Thara Gopinath <thara.gopinath@...aro.org>
> > Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> > Cc: Rob Herring <robh+dt@...nel.org>
> > Cc: Andy Gross <agross@...nel.org>
> > Cc: Herbert Xu <herbert@...dor.apana.org.au>
> > Cc: David S. Miller <davem@...emloft.net>
> > Cc: Stephen Boyd <sboyd@...nel.org>
> > Cc: Michael Turquette <mturquette@...libre.com>
> > Cc: Vinod Koul <vkoul@...nel.org>
> > Cc: dmaengine@...r.kernel.org
> > Cc: linux-clk@...r.kernel.org
> > Cc: linux-crypto@...r.kernel.org
> > Cc: devicetree@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Cc: bhupesh.linux@...il.com
> > Signed-off-by: Bhupesh Sharma <bhupesh.sharma@...aro.org>
> > ---
> >   drivers/crypto/qce/core.c | 14 ++++++++++++++
> >   1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/crypto/qce/core.c b/drivers/crypto/qce/core.c
> > index 3e742e9911fa..9915b184f780 100644
> > --- a/drivers/crypto/qce/core.c
> > +++ b/drivers/crypto/qce/core.c
> > @@ -222,6 +222,20 @@ static int qce_crypto_probe(struct platform_device *pdev)
> >               return ret;
> >
> >       qce->mem_path = of_icc_get(qce->dev, "memory");
> > +
> > +     /* Check for NULL return path, which indicates
> > +      * interconnect API is disabled or the "interconnects"
> > +      * DT property is missing.
> > +      */
> > +     if (!qce->mem_path)
> > +             /* On some qcom parts, the qce crypto block needs interconnect
> > +              * paths to be configured before the registers can be accessed.
> > +              * Check here for the same.
> > +              */
> > +             if (!strcmp(of_id->compatible, "qcom,ipq6018-qce") ||
> > +                 !strcmp(of_id->compatible, "qcom,sdm845-qce"))
> > +                     return -EPROBE_DEFER;
> > +
>
> Hi Bhupesh,
>
> You don't need this here. of_icc_get returns -EPROBE_DEFER if the
> interconnect provider is not initialized yet.

Thanks for the review.

Yes, I finished testing all the possible combinations with qce, bam
dma and interconnect drivers compiled as modules v/s as static parts
of the kernel and we don't need this extra check for the interconnect
here. We should be fine with checking just the qce_dma_request()
return value and returning early in the qce probe() flow if no dma
channels are yet available from the bam dma driver.

I have made the changes in v3 and will post it for review shortly.

Regards,
Bhupesh