netdev - Re: [PATCH net-next v4 10/13] net: wwan: t7xx: Introduce power management support

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Date:   Thu, 10 Feb 2022 12:58:31 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Ricardo Martinez <ricardo.martinez@...ux.intel.com>
cc:     Netdev <netdev@...r.kernel.org>, linux-wireless@...r.kernel.org,
        kuba@...nel.org, davem@...emloft.net, johannes@...solutions.net,
        ryazanov.s.a@...il.com, loic.poulain@...aro.org,
        m.chetan.kumar@...el.com, chandrashekar.devegowda@...el.com,
        linuxwwan@...el.com, chiranjeevi.rapolu@...ux.intel.com,
        haijun.liu@...iatek.com, amir.hanania@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        dinesh.sharma@...el.com, eliot.lee@...el.com,
        moises.veleta@...el.com, pierre-louis.bossart@...el.com,
        muralidharan.sethuraman@...el.com, Soumya.Prakash.Mishra@...el.com,
        sreehari.kancharla@...el.com
Subject: Re: [PATCH net-next v4 10/13] net: wwan: t7xx: Introduce power
 management support

On Thu, 13 Jan 2022, Ricardo Martinez wrote:

> From: Haijun Liu <haijun.liu@...iatek.com>
> 
> Implements suspend, resumes, freeze, thaw, poweroff, and restore
> `dev_pm_ops` callbacks.
> 
> >From the host point of view, the t7xx driver is one entity. But, the
> device has several modules that need to be addressed in different ways
> during power management (PM) flows.
> The driver uses the term 'PM entities' to refer to the 2 DPMA and
> 2 CLDMA HW blocks that need to be managed during PM flows.
> When a dev_pm_ops function is called, the PM entities list is iterated
> and the matching function is called for each entry in the list.
> 
> Signed-off-by: Haijun Liu <haijun.liu@...iatek.com>
> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@...el.com>
> Co-developed-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> Signed-off-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> ---


>  	if (ret) {
>  		dev_err(dev, "Failed to allocate RX/TX SW resources: %d\n", ret);
> +		t7xx_dpmaif_pm_entity_release(dpmaif_ctrl);
>  		return NULL;

Print after release.


> +static int __t7xx_pci_pm_suspend(struct pci_dev *pdev)
> +{
> +	struct t7xx_pci_dev *t7xx_dev;
> +	struct md_pm_entity *entity;
> +	unsigned long wait_ret;
> +	enum t7xx_pm_id id;
> +	int ret = 0;
> +
> +	t7xx_dev = pci_get_drvdata(pdev);
> +	if (atomic_read(&t7xx_dev->md_pm_state) <= MTK_PM_INIT) {
> +		dev_err(&pdev->dev,
> +			"[PM] Exiting suspend, because handshake failure or in an exception\n");
> +		return -EFAULT;
> +	}
> +
> +	iowrite32(L1_DISABLE_BIT(0), IREG_BASE(t7xx_dev) + DIS_ASPM_LOWPWR_SET_0);
> +
> +	ret = t7xx_wait_pm_config(t7xx_dev);
> +	if (ret)
> +		return ret;

Do you need to rollback the iowrite?

> +	atomic_set(&t7xx_dev->md_pm_state, MTK_PM_SUSPENDED);
> +	t7xx_pcie_mac_clear_int(t7xx_dev, SAP_RGU_INT);
> +	t7xx_dev->rgu_pci_irq_en = false;
> +
> +	list_for_each_entry(entity, &t7xx_dev->md_pm_entities, entity) {
> +		if (entity->suspend) {
> +			ret = entity->suspend(t7xx_dev, entity->entity_param);
> +			if (ret) {
> +				id = entity->id;
> +				break;
> +			}
> +		}
> +	}
> +
> +	if (ret) {
> +		dev_err(&pdev->dev, "[PM] Suspend error: %d, id: %d\n", ret, id);
> +
> +		list_for_each_entry(entity, &t7xx_dev->md_pm_entities, entity) {
> +			if (id == entity->id)
> +				break;
> +
> +			if (entity->resume)
> +				entity->resume(t7xx_dev, entity->entity_param);
> +		}
> +
> +		goto suspend_complete;

Suspend failure path(?) gotos to "suspend_complete"?

> +	}
> +
> +	reinit_completion(&t7xx_dev->pm_sr_ack);
> +	t7xx_mhccif_h2d_swint_trigger(t7xx_dev, H2D_CH_SUSPEND_REQ);
> +	wait_ret = wait_for_completion_timeout(&t7xx_dev->pm_sr_ack,
> +					       msecs_to_jiffies(PM_ACK_TIMEOUT_MS));
> +	if (!wait_ret)
> +		dev_err(&pdev->dev, "[PM] Wait for device suspend ACK timeout-MD\n");
> +
> +	reinit_completion(&t7xx_dev->pm_sr_ack);
> +	t7xx_mhccif_h2d_swint_trigger(t7xx_dev, H2D_CH_SUSPEND_REQ_AP);
> +	wait_ret = wait_for_completion_timeout(&t7xx_dev->pm_sr_ack,
> +					       msecs_to_jiffies(PM_ACK_TIMEOUT_MS));
> +	if (!wait_ret)
> +		dev_err(&pdev->dev, "[PM] Wait for device suspend ACK timeout-SAP\n");
> +
> +	list_for_each_entry(entity, &t7xx_dev->md_pm_entities, entity) {
> +		if (entity->suspend_late)
> +			entity->suspend_late(t7xx_dev, entity->entity_param);
> +	}
> +
> +suspend_complete:
> +	iowrite32(L1_DISABLE_BIT(0), IREG_BASE(t7xx_dev) + DIS_ASPM_LOWPWR_CLR_0);
> +
> +	if (ret) {
> +		atomic_set(&t7xx_dev->md_pm_state, MTK_PM_RESUMED);
> +		t7xx_pcie_mac_set_int(t7xx_dev, SAP_RGU_INT);
> +	}
> +
> +	return ret;
> +}

Please check all paths in this function. I found enough oddities to not 
be able to convince myself I understood it all or found all the problems.
As if, e.g., an ok path return would be missing above misnamed 
suspend_complete label (but then there's if (ret) below it which is kind 
of counterargument against my reasoning).

I've no comments on patches 11-13.

-- 
 i.