Re: [PATCH 5/7] i3c: mipi-i3c-hci: Allow parent to manage runtime PM

[Frank Li <Frank.li@nxp.com>]

On Thu, Jan 29, 2026 at 08:18:39PM +0200, Adrian Hunter wrote:
> Some platforms implement the MIPI I3C HCI Multi-Bus Instance capability,
> where a single parent device hosts multiple I3C controller instances.  In
> such designs, the parent - not the individual child instances - may need to
> coordinate runtime PM so that all controllers enter low-power states
> together, and all runtime suspend callbacks are invoked in a controlled
> and synchronized manner.
>
> For example, if the parent enables IBI-wakeup when transitioning into a
> low-power state,

Does your hardware support recieve IBI when runtime suspend?

Frank

> every bus instance must remain able to receive IBIs up
> until that point.  This requires deferring the individual controllers’
> runtime suspend callbacks (which disable bus activity) until the parent
> decides it is safe for all instances to suspend together.
>
> To support this usage model:
>
>   * Export the controller's runtime PM suspend/resume callbacks so that
>     the parent can invoke them directly.
>
>   * Add a new quirk, HCI_QUIRK_RPM_PARENT_MANAGED, which designates the
>     parent device as the controller’s runtime PM device (rpm_dev).  When
>     used without HCI_QUIRK_RPM_ALLOWED, this also prevents the child
>     instance’s system-suspend callbacks from using
>     pm_runtime_force_suspend()/pm_runtime_force_resume(), since runtime
>     PM is managed entirely by the parent.
>
>   * Move DEFAULT_AUTOSUSPEND_DELAY_MS into the header so it can be shared
>     by parent-managed PM implementations.
>
> The new quirk allows platforms with multi-bus parent-managed PM
> infrastructure to correctly coordinate runtime PM across all I3C HCI
> instances.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
>  drivers/i3c/master/mipi-i3c-hci/core.c | 25 ++++++++++++++++---------
>  drivers/i3c/master/mipi-i3c-hci/hci.h  |  6 ++++++
>  2 files changed, 22 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
> index ec4dbe64c35e..cb974b0f9e17 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
> @@ -733,7 +733,7 @@ static int i3c_hci_reset_and_init(struct i3c_hci *hci)
>  	return 0;
>  }
>
> -static int i3c_hci_runtime_suspend(struct device *dev)
> +int i3c_hci_runtime_suspend(struct device *dev)
>  {
>  	struct i3c_hci *hci = dev_get_drvdata(dev);
>  	int ret;
> @@ -746,8 +746,9 @@ static int i3c_hci_runtime_suspend(struct device *dev)
>
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(i3c_hci_runtime_suspend);
>
> -static int i3c_hci_runtime_resume(struct device *dev)
> +int i3c_hci_runtime_resume(struct device *dev)
>  {
>  	struct i3c_hci *hci = dev_get_drvdata(dev);
>  	int ret;
> @@ -768,6 +769,7 @@ static int i3c_hci_runtime_resume(struct device *dev)
>
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(i3c_hci_runtime_resume);
>
>  static int i3c_hci_suspend(struct device *dev)
>  {
> @@ -784,12 +786,14 @@ static int i3c_hci_resume_common(struct device *dev, bool rstdaa)
>  	struct i3c_hci *hci = dev_get_drvdata(dev);
>  	int ret;
>
> -	if (!(hci->quirks & HCI_QUIRK_RPM_ALLOWED))
> -		return 0;
> +	if (!(hci->quirks & HCI_QUIRK_RPM_PARENT_MANAGED)) {
> +		if (!(hci->quirks & HCI_QUIRK_RPM_ALLOWED))
> +			return 0;
>
> -	ret = pm_runtime_force_resume(dev);
> -	if (ret)
> -		return ret;
> +		ret = pm_runtime_force_resume(dev);
> +		if (ret)
> +			return ret;
> +	}
>
>  	ret = i3c_master_do_daa_ext(&hci->master, rstdaa);
>  	if (ret)
> @@ -812,8 +816,6 @@ static int i3c_hci_restore(struct device *dev)
>  	return i3c_hci_resume_common(dev, true);
>  }
>
> -#define DEFAULT_AUTOSUSPEND_DELAY_MS 1000
> -
>  static void i3c_hci_rpm_enable(struct device *dev)
>  {
>  	struct i3c_hci *hci = dev_get_drvdata(dev);
> @@ -962,6 +964,11 @@ static int i3c_hci_probe(struct platform_device *pdev)
>  	if (hci->quirks & HCI_QUIRK_RPM_IBI_ALLOWED)
>  		hci->master.rpm_ibi_allowed = true;
>
> +	if (hci->quirks & HCI_QUIRK_RPM_PARENT_MANAGED) {
> +		hci->master.rpm_dev = pdev->dev.parent;
> +		hci->master.rpm_allowed = true;
> +	}
> +
>  	return i3c_master_register(&hci->master, &pdev->dev, &i3c_hci_ops, false);
>  }
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
> index 819328a85b84..d0e7ad58ac15 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/hci.h
> +++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
> @@ -147,6 +147,7 @@ struct i3c_hci_dev_data {
>  #define HCI_QUIRK_RESP_BUF_THLD		BIT(4)  /* Set resp buf thld to 0 for AMD platforms */
>  #define HCI_QUIRK_RPM_ALLOWED		BIT(5)  /* Runtime PM allowed */
>  #define HCI_QUIRK_RPM_IBI_ALLOWED	BIT(6)  /* IBI and Hot-Join allowed while runtime suspended */
> +#define HCI_QUIRK_RPM_PARENT_MANAGED	BIT(7)  /* Runtime PM managed by parent device */
>
>  /* global functions */
>  void mipi_i3c_hci_resume(struct i3c_hci *hci);
> @@ -156,4 +157,9 @@ void amd_set_od_pp_timing(struct i3c_hci *hci);
>  void amd_set_resp_buf_thld(struct i3c_hci *hci);
>  void i3c_hci_sync_irq_inactive(struct i3c_hci *hci);
>
> +#define DEFAULT_AUTOSUSPEND_DELAY_MS 1000
> +
> +int i3c_hci_runtime_suspend(struct device *dev);
> +int i3c_hci_runtime_resume(struct device *dev);
> +
>  #endif
> --
> 2.51.0
>