[PATCH V2 13/14] i3c: mipi-i3c-hci: Fix handling of shared IRQs during early initialization

[Frank Li]

On Wed, Mar 04, 2026 at 08:17:04PM +0200, Adrian Hunter wrote:
> Shared interrupts may fire unexpectedly, including during periods when the
> controller is not yet fully initialized. Commit b9a15012a1452
> ("i3c: mipi-i3c-hci: Add optional Runtime PM support") addressed this issue
> for the runtime-suspended state, but the same problem can also occur before
> the bus is enabled for the first time.
>
> Ensure the IRQ handler ignores interrupts until initialization is complete
> by making consistent use of the existing irq_inactive flag.  The flag is
> now set to false immediately before enabling the bus.
>
> To guarantee correct ordering with respect to the IRQ handler, protect
> all transitions of irq_inactive with the same spinlock used inside the
> handler.
>
> Fixes: b8460480f62e1 ("i3c: mipi-i3c-hci: Allow for Multi-Bus Instances")
> Cc: stable at vger.kernel.org
> Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
> ---

Reviewed-by: Frank Li <Frank.Li at nxp.com>

>
>
> Changes in V2:
>
> 	Place irq_inactive under the protection of the now unified
> 	spinlock, eliminating the need for explict memory barriers.
> 	Correctly position the update of irq_inactive in
> 	i3c_hci_sync_irq_inactive() to after synchronize_irq()
>
>
>  drivers/i3c/master/mipi-i3c-hci/core.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
> index b98952d12d7c..d5e91af7d569 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
> @@ -152,6 +152,9 @@ static int i3c_hci_bus_init(struct i3c_master_controller *m)
>  	if (hci->quirks & HCI_QUIRK_RESP_BUF_THLD)
>  		amd_set_resp_buf_thld(hci);
>
> +	scoped_guard(spinlock_irqsave, &hci->lock)
> +		hci->irq_inactive = false;
> +
>  	/* Enable bus with Hot-Join disabled */
>  	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
>  	dev_dbg(&hci->master.dev, "HC_CONTROL = %#x", reg_read(HC_CONTROL));
> @@ -184,8 +187,9 @@ void i3c_hci_sync_irq_inactive(struct i3c_hci *hci)
>  	int irq = platform_get_irq(pdev, 0);
>
>  	reg_write(INTR_SIGNAL_ENABLE, 0x0);
> -	hci->irq_inactive = true;
>  	synchronize_irq(irq);
> +	scoped_guard(spinlock_irqsave, &hci->lock)
> +		hci->irq_inactive = true;
>  }
>
>  static void i3c_hci_bus_cleanup(struct i3c_master_controller *m)
> @@ -781,10 +785,11 @@ static int i3c_hci_runtime_resume(struct device *dev)
>
>  	mipi_i3c_hci_dat_v1.restore(hci);
>
> -	hci->irq_inactive = false;
> -
>  	hci->io->resume(hci);
>
> +	scoped_guard(spinlock_irqsave, &hci->lock)
> +		hci->irq_inactive = false;
> +
>  	/* Enable bus with Hot-Join disabled */
>  	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
>
> @@ -975,6 +980,8 @@ static int i3c_hci_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>
> +	hci->irq_inactive = true;
> +
>  	irq = platform_get_irq(pdev, 0);
>  	ret = devm_request_irq(&pdev->dev, irq, i3c_hci_irq_handler,
>  			       IRQF_SHARED, NULL, hci);
> --
> 2.51.0
>
>
> --
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