Re: [PATCH v6] i2c: mux: reg: use device property accessors

[Abdurrahman Hussain]

On Tue May 19, 2026 at 11:55 PM PDT, Wolfram Sang wrote:
> On Tue, May 19, 2026 at 02:18:50PM -0700, Abdurrahman Hussain wrote:
>> Convert the device-tree parsing path to the generic fwnode/device
>> property accessors so the driver can be probed on ACPI and swnode
>> platforms as well as OF. The helper is renamed from
>> i2c_mux_reg_probe_dt() to i2c_mux_reg_probe_fw() to reflect that.
>> 
>> Accessor translation:
>> 
>>   of_parse_phandle("i2c-parent") +
>>     of_find_i2c_adapter_by_node()    -> fwnode_find_reference() +
>>                                          i2c_find_adapter_by_fwnode()
>>   of_get_child_count()               -> device_get_child_node_count()
>>   of_property_read_bool()            -> device_property_read_bool()
>>   for_each_child_of_node()           -> device_for_each_child_node()
>>     of_property_read_u32("reg")        on ACPI device nodes:
>>                                          acpi_get_local_address()
>>                                        everything else (OF, swnode,
>>                                        ACPI data nodes):
>>                                          fwnode_property_read_u32()
>>   of_property_read_u32("idle-state") -> device_property_read_u32()
>> 
>> The child-node branch uses is_acpi_device_node() rather than
>> is_acpi_node(): the latter also matches ACPI data nodes (the
>> _DSD hierarchical-property children used by PRP0001-style
>> firmware), which have no ACPI handle and would make
>> acpi_get_local_address() fall back to evaluating _ADR against the
>> root namespace and return -ENODATA.  Routing data nodes through
>> fwnode_property_read_u32() instead lets them resolve the "reg"
>> property the same way OF and swnode children do.
>> 
>> Behavioural preservations (deliberate, to avoid regressing existing
>> users):
>> 
>>   - The three-way endian fallback is kept verbatim: an explicit
>>     "little-endian" property wins, then "big-endian", and otherwise
>>     the host's compile-time byte order. device_is_big_endian() is
>>     not used here because it ignores "little-endian" and introduces
>>     "native-endian" semantics, which would diverge from the binding.
>> 
>>   - The "if (!mux->data.reg)" guard around
>>     devm_platform_get_and_ioremap_resource() in probe() is kept.
>>     drivers/platform/mellanox/mlx-platform.c registers i2c-mux-reg
>>     platform_devices with no memory resource and supplies a
>>     pre-set .reg / .reg_size through struct
>>     i2c_mux_reg_platform_data; without the guard those
>>     registrations would fail in probe().
>> 
>>   - The "if (!mux->data.reg)" ioremap block (and the paired
>>     reg_size validation that depends on it) is hoisted above
>>     i2c_get_adapter(mux->data.parent), so the fwnode path
>>     preserves master's ordering of "ioremap before parent-adapter
>>     get".  For platdata users the validation runs from a slightly
>>     earlier position, but mux->data.reg_size is already set from
>>     platdata by then, so the order is functionally neutral.
>> 
>> The OF-only of_address_to_resource() translation in the old
>> probe_dt() is dropped because the same address is available from
>> the platform_device resource table on OF as well as ACPI, and the
>> existing fallback in probe() ioremaps it.
>> 
>> Acked-by: Peter Rosin <peda@xxxxxxxxxxxxxx>
>> Signed-off-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
>> Assisted-by: Claude-Code:claude-opus-4-7
>> Assisted-by: sashiko:gemini-3.1-pro-preview
>
> Acked-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>

Hi Wolfram,

I noticed this patch didn't make it into 7.1-rc5. Is it still under
review? If not, will it make it during the next merge window?

Best regards,
Abdurrahman