Re: [PATCH 04/17] i3c: master: Match ACPI targets to the correct bus controller instance

[Frank Li]

On Mon, Sep 14, 2026 at 02:29:50PM +0300, Adrian Hunter wrote:
> For ACPI-enumerated I3C targets, _ADR encodes both the zero-based bus
> controller instance number in bits 51:48 and the Provisioned ID (PID)
> in bits 47:0, as defined by ACPI 6.6 Table 6.2 and MIPI DisCo for I3C
> v1.1 section 5.2.
>
> However, i3c_master_add_acpi_dev() treats the entire _ADR value as the
> PID. On multi-instance controllers this folds the instance number into
> the PID, causing i3c_master_add_i3c_boardinfo() to reject devices on
> instance 1 and above with -EINVAL.
>
> The problem is exposed by the MIPI I3C HCI PCI driver, which creates one
> MFD child device per bus controller instance. Since the child devices do
> not have their own ACPI companions, they all inherit the parent's ACPI
> node and therefore enumerate the same set of child devices. As a result,
> a target belonging to any instance other than 0 prevents registration of
> all controller instances.
>
> Add an instance number to struct i3c_master_controller, propagate it
> from the HCI PCI driver, extract the PID from bits 47:0 of _ADR, and
> ignore ACPI child nodes that belong to a different controller instance.
>
> ACPI-enumerated I2C devices are unaffected. Their controller instance is
> encoded in the Resource Source Index of the I2cSerialBusV2 descriptor
> rather than in _ADR and will require separate handling.
>
> Fixes: b46a4b3c5d1e ("i3c: master: Support ACPI enumeration of child devices")
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/i3c/master.c                          | 19 +++++++++++++++++--
>  drivers/i3c/master/mipi-i3c-hci/core.c        |  4 +++-
>  .../master/mipi-i3c-hci/mipi-i3c-hci-pci.c    |  1 +
>  include/linux/i3c/master.h                    |  3 +++
>  include/linux/platform_data/mipi-i3c-hci.h    |  4 ++++
>  5 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index f9a6c8560fab..215a22f2c7b6 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -8,6 +8,7 @@
>  #include <dt-bindings/i3c/i3c.h>
>  #include <linux/acpi.h>
>  #include <linux/atomic.h>
> +#include <linux/bitfield.h>
>  #include <linux/bitmap.h>
>  #include <linux/bug.h>
>  #include <linux/delay.h>
> @@ -3076,6 +3077,13 @@ static int i3c_master_add_of_dev(struct i3c_master_controller *master,
>  	return ret;
>  }
>
> +#define I3C_ACPI_ADR_PID GENMASK_U64(47, 0)
> +/*
> + * Zero-based instance number of the Bus Controller to which the Target is
> + * connected.
> + */
> +#define I3C_ACPI_ADR_INSTANCE GENMASK_U64(51, 48)
> +
>  #ifdef CONFIG_ACPI
>  static int i3c_master_add_acpi_dev(struct i3c_master_controller *master,
>  				   struct fwnode_handle *fwnode)
> @@ -3083,6 +3091,7 @@ static int i3c_master_add_acpi_dev(struct i3c_master_controller *master,
>  	struct acpi_device *adev = to_acpi_device_node(fwnode);
>  	acpi_bus_address adr;
>  	u32 reg[3] = { 0 };
> +	u64 pid;
>  	int ret;
>
>  	/*
> @@ -3100,9 +3109,15 @@ static int i3c_master_add_acpi_dev(struct i3c_master_controller *master,
>
>  	adr = acpi_device_adr(adev);
>
> +	/* Match the multi-bus instance number */
> +	if (FIELD_GET(I3C_ACPI_ADR_INSTANCE, adr) != master->instance)
> +		return 0;
> +
>  	/* For I3C devices, _ADR will have the 48 bit PID of the device  */
> -	reg[1] = upper_32_bits(adr);
> -	reg[2] = lower_32_bits(adr);
> +	pid = FIELD_GET(I3C_ACPI_ADR_PID, adr);
> +
> +	reg[1] = upper_32_bits(pid);
> +	reg[2] = lower_32_bits(pid);
>
>  	fwnode_property_read_u32(fwnode, "mipi-i3c-static-address", &reg[0]);
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
> index dadf049bd4b5..8b3a87d8a8bb 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
> @@ -1142,8 +1142,10 @@ static int i3c_hci_probe(struct platform_device *pdev)
>  	 * necessarily in separate contiguous sub-ranges. To avoid overlapping
>  	 * mappings, provide base_regs from the parent mapping.
>  	 */
> -	if (pdata)
> +	if (pdata) {
>  		hci->base_regs = pdata->base_regs;
> +		hci->master.instance = pdata->instance;
> +	}
>
>  	if (!hci->base_regs) {
>  		hci->base_regs = devm_platform_ioremap_resource(pdev, 0);
> diff --git a/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c b/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
> index af9595009b03..5b8e10d05cee 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
> @@ -390,6 +390,7 @@ static void mipi_i3c_hci_pci_setup_cell(struct mipi_i3c_hci_pci *hci, int idx,
>  					struct mfd_cell *cell)
>  {
>  	data->pdata.base_regs = hci->base + hci->info->instance_offset[idx];
> +	data->pdata.instance = idx;
>
>  	data->res = DEFINE_RES_IRQ(0);
>
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index f7ceec2b4477..72065715feee 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -536,6 +536,8 @@ struct i3c_master_controller_ops {
>   *		 Bit 0: SETDASA
>   *		 Bit 1: SETAASA
>   *		 All other bits are reserved.
> + * @instance: Zero-based instance number of the Bus Controller as defined by the
> + *            DisCo specification I3C Target Address (_ADR) Encoding
>   * @wq: freezable workqueue which can be used by master
>   *	drivers if they need to postpone operations that need to take place
>   *	in a thread context. Typical examples are Hot Join processing which
> @@ -573,6 +575,7 @@ struct i3c_master_controller {
>  	} boardinfo;
>  	struct i3c_bus bus;
>  	u8 addr_method;
> +	u8 instance;
>  	struct workqueue_struct *wq;
>  	struct work_struct hj_work;
>  	struct work_struct reg_work;
> diff --git a/include/linux/platform_data/mipi-i3c-hci.h b/include/linux/platform_data/mipi-i3c-hci.h
> index ab7395f455f9..6f61d8a02378 100644
> --- a/include/linux/platform_data/mipi-i3c-hci.h
> +++ b/include/linux/platform_data/mipi-i3c-hci.h
> @@ -3,13 +3,17 @@
>  #define INCLUDE_PLATFORM_DATA_MIPI_I3C_HCI_H
>
>  #include <linux/compiler_types.h>
> +#include <linux/types.h>
>
>  /**
>   * struct mipi_i3c_hci_platform_data - Platform-dependent data for mipi_i3c_hci
>   * @base_regs: Register set base address (to support multi-bus instances)
> + * @instance: Zero-based instance number of the Bus Controller as defined by the
> + *            DisCo specification I3C Target Address (_ADR) Encoding
>   */
>  struct mipi_i3c_hci_platform_data {
>  	void __iomem *base_regs;
> +	u8 instance;
>  };
>
>  #endif
> --
> 2.53.0
>