linux-kernel - Re: [PATCH 4/4] soc: samsung: exynos-pmu: enable CPU hotplug support for gs101

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Message-ID: <fbdeffe0-c908-4df1-9096-350a7d330570@kernel.org>
Date: Sun, 22 Dec 2024 13:17:18 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Peter Griffin <peter.griffin@...aro.org>, Rob Herring <robh@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Lee Jones <lee@...nel.org>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
 tudor.ambarus@...aro.org, andre.draszik@...aro.org, willmcvicker@...gle.com,
 kernel-team@...roid.com
Subject: Re: [PATCH 4/4] soc: samsung: exynos-pmu: enable CPU hotplug support
 for gs101

On 13/12/2024 17:44, Peter Griffin wrote:
>  /*
> @@ -325,6 +328,52 @@ struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
>  }
>  EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
>  
> +/*
> + * CPU_INFORM register hint values which are used by
> + * EL3 firmware (el3mon).
> + */
> +#define CPU_INFORM_CLEAR	0
> +#define CPU_INFORM_C2		1
> +
> +static int cpuhp_pmu_online(unsigned int cpu)

exynos_cpuhp_pmu_online
or gs101_cpuhp_pmu_online
same for offline

> +{
> +	void __iomem *base = pmu_context->pmuintrgen_base;
> +	u32 reg;
> +	u32 mask;
> +
> +	/* clear cpu inform hint */
> +	regmap_write(pmu_context->pmureg, GS101_CPU_INFORM(cpu),
> +		     CPU_INFORM_CLEAR);
> +
> +	mask = (1 << cpu);

BIT(cpu)

> +
> +	writel(((0 << cpu) & mask), base + GS101_GRP2_INTR_BID_ENABLE);

I am not sure if I follow. You want to zero-out all other bits or enable
all other bits?

> +
> +	reg = readl(base + GS101_GRP2_INTR_BID_UPEND) & mask;
> +	writel(reg & mask, base + GS101_GRP2_INTR_BID_CLEAR);

reg is &mask twice.

I don't follow this either, are these auto-cleared? It feels like you
wanted to update some bits, but you are updating entire registers in
both cases.


> +
> +	return 0;
> +}
> +
> +static int cpuhp_pmu_offline(unsigned int cpu)
> +{
> +	void __iomem *base = pmu_context->pmuintrgen_base;
> +	u32 reg, mask;
> +
> +	/* set cpu inform hint */
> +	regmap_write(pmu_context->pmureg, GS101_CPU_INFORM(cpu),
> +		     CPU_INFORM_C2);
> +
> +	writel((1 << cpu), base + GS101_GRP2_INTR_BID_ENABLE);
> +
> +	mask = ((1 << cpu) | (1 << (cpu+8)));

What does 8 stands for?

> +
> +	reg = readl(base + GS101_GRP1_INTR_BID_UPEND) & mask;
> +	writel(reg & mask, base + GS101_GRP1_INTR_BID_CLEAR);
> +
> +	return 0;
> +}
> +
>  static int exynos_pmu_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -377,6 +426,28 @@ static int exynos_pmu_probe(struct platform_device *pdev)
>  	pmu_context->pmureg = regmap;
>  	pmu_context->dev = dev;
>  
> +	if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_cpuhp) {
> +

Drop blank line

> +		pmu_context->pmuintrgen_base =
> +			devm_platform_ioremap_resource_byname(pdev, "pmu-intr-gen");
> +		/*
> +		 * To maintain support for older DTs that didn't specify pmu-intr-gen
> +		 * register region, just issue a warning rather than fail to probe.
> +		 */
> +		if (IS_ERR(pmu_context->pmuintrgen_base)) {
> +			dev_warn(&pdev->dev,
> +				 "failed to map pmu-intr-gen registers\n");

Test old DTS, I think you do write() to the ERR_PTR when
offlining/onlining...

> +		} else {
> +			cpuhp_setup_state(CPUHP_BP_PREPARE_DYN,
> +					"soc/exynos-pmu:prepare",
> +					cpuhp_pmu_online, NULL);
> +
> +			cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> +					"soc/exynos-pmu:online",
> +					NULL, cpuhp_pmu_offline);
> +		}
> +	}
> +
>  	if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_init)
>  		pmu_context->pmu_data->pmu_init();
>  



Best regards,
Krzysztof