linux-kernel - Re: [PATCH 2/5] interconnect: qcom: icc-rpmh: Get parent's regmap for nested NoCs

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Message-ID: <iwlvslb3yzmal7m5dpks46s2jv2v72hhrtrmirtptjmt3pgvks@bs6ohfgefmro>
Date: Sat, 8 Nov 2025 19:46:34 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Luca Weiss <luca.weiss@...rphone.com>
Cc: Georgi Djakov <djakov@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] interconnect: qcom: icc-rpmh: Get parent's regmap
 for nested NoCs

On Fri, Nov 07, 2025 at 05:08:48PM +0100, Luca Weiss wrote:
> Since commit 57eb14779dfd ("interconnect: qcom: icc-rpmh: Support child
> NoC device probe") the icc-rpmh driver supports initializing child NoCs,
> but those child NoCs also need to be able to get the parent's regmap in
> order to enable QoS.
> 
> Change the driver to support that and support programming QoS register.
> 
> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
> ---
>  drivers/interconnect/qcom/icc-rpmh.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpmh.c b/drivers/interconnect/qcom/icc-rpmh.c
> index f90c29111f48..2103185a44a5 100644
> --- a/drivers/interconnect/qcom/icc-rpmh.c
> +++ b/drivers/interconnect/qcom/icc-rpmh.c
> @@ -308,7 +308,16 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>  		struct resource *res;
>  		void __iomem *base;
>  
> -		base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> +		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +		if (!res) {
> +			/* Try parent's regmap */
> +			qp->regmap = dev_get_regmap(dev->parent, NULL);
> +			if (qp->regmap)
> +				goto regmap_done;

And this turns into spaghetty. What about:

	qp->regmap = dev_get_regmap();
	if (!qp->regmap) {
	   base = devm_platform_get_and_ioremap_resource();
	   // handle the error
	   qp->regmap = devm_regmap_init_mmio();
	   // handle the error, goto skip_qos_config
	}


> +			goto skip_qos_config;
> +		}
> +
> +		base = devm_ioremap_resource(dev, res);
>  		if (IS_ERR(base))
>  			goto skip_qos_config;
>  
> @@ -318,6 +327,7 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>  			goto skip_qos_config;
>  		}
>  
> +regmap_done:
>  		qp->num_clks = devm_clk_bulk_get_all(qp->dev, &qp->clks);
>  		if (qp->num_clks == -EPROBE_DEFER)
>  			return dev_err_probe(dev, qp->num_clks, "Failed to get QoS clocks\n");
> 
> -- 
> 2.51.2
> 

-- 
With best wishes
Dmitry