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Subject: Re: [PATCH v5 6/8] cpuidle: Add RISC-V SBI CPU idle driver
To:     Anup Patel <anup.patel@wdc.com>
Cc:     Sandeep Tripathy <milun.tripathy@gmail.com>,
        Atish Patra <atish.patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Liush <liush@allwinnertech.com>,
        Anup Patel <anup@brainfault.org>, devicetree@vger.kernel.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Pavel Machek <pavel@ucw.cz>
References: <20210602112321.2241566-1-anup.patel@wdc.com>
 <20210602112321.2241566-7-anup.patel@wdc.com>
From:   Samuel Holland <samuel@sholland.org>
Message-ID: <26cddfa8-75e2-7b5b-1a47-e01cc1c7821e@sholland.org>
Date:   Sun, 6 Jun 2021 13:39:43 -0500
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On 6/2/21 6:23 AM, Anup Patel wrote:
> The RISC-V SBI HSM extension provides HSM suspend call which can
> be used by Linux RISC-V to enter platform specific low-power state.
> 
> This patch adds a CPU idle driver based on RISC-V SBI calls which
> will populate idle states from device tree and use SBI calls to
> entry these idle states.
> 
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> ---
>  MAINTAINERS                   |   7 +
>  drivers/cpuidle/Kconfig       |   5 +
>  drivers/cpuidle/Kconfig.riscv |  15 +
>  drivers/cpuidle/Makefile      |   4 +
>  drivers/cpuidle/cpuidle-sbi.c | 626 ++++++++++++++++++++++++++++++++++
>  5 files changed, 657 insertions(+)
>  create mode 100644 drivers/cpuidle/Kconfig.riscv
>  create mode 100644 drivers/cpuidle/cpuidle-sbi.c
> 
> ...
> diff --git a/drivers/cpuidle/cpuidle-sbi.c b/drivers/cpuidle/cpuidle-sbi.c
> new file mode 100644
> index 000000000000..f743684d07de
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-sbi.c
> @@ -0,0 +1,626 @@
> ...
> +	/* Initialize idle states from DT. */
> +	ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
> +	if (ret) {
> +		pr_err("HART%ld: failed to init idle states\n",
> +		       cpuid_to_hartid_map(cpu));
> +		return ret;
> +	}
> +
> +	ret = cpuidle_register(drv, NULL);
> +	if (ret)
> +		goto deinit;
> +
> +	cpuidle_cooling_register(drv);
> +
> +	return 0;
> +deinit:
> +	sbi_cpuidle_deinit_cpu(cpu);
> +	return ret;
> +}
> +
> +static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)

This function should be moved inside the CONFIG_DT_IDLE_GENPD block
below. Otherwise it is defined but unused.

> +{
> +	struct genpd_power_state *state = &pd->states[pd->state_idx];
> +	u32 *pd_state;
> +
> +	if (!state->data)
> +		return 0;
> +
> +	if (!sbi_cpuidle_pd_allow_domain_state)
> +		return -EBUSY;
> +
> +	/* OSI mode is enabled, set the corresponding domain state. */
> +	pd_state = state->data;
> +	sbi_set_domain_state(*pd_state);
> +
> +	return 0;
> +}
> +
> +static void sbi_cpuidle_domain_sync_state(struct device *dev)
> +{
> +	/*
> +	 * All devices have now been attached/probed to the PM domain
> +	 * topology, hence it's fine to allow domain states to be picked.
> +	 */
> +	sbi_cpuidle_pd_allow_domain_state = true;
> +}
> +
> +#ifdef CONFIG_DT_IDLE_GENPD
> +
> +struct sbi_pd_provider {
> +	struct list_head link;
> +	struct device_node *node;
> +};
> +
> +static LIST_HEAD(sbi_pd_providers);
> +
> +static int sbi_pd_init(struct device_node *np)
> +{
> +	struct generic_pm_domain *pd;
> +	struct sbi_pd_provider *pd_provider;
> +	struct dev_power_governor *pd_gov;
> +	int ret = -ENOMEM, state_count = 0;
> +
> +	pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
> +	if (!pd)
> +		goto out;
> ...