On 10/03/2015 05:04 AM, Marc Zyngier wrote:
> On Fri, 2 Oct 2015 16:06:05 -0500
> Wei Huang <w...@redhat.com> wrote:
>
> Hi Wei,
>
>> Hi Marc,
>
> [...]
>
>>> +struct acpi_probe_entry {
>>> + __u8 id[ACPI_TABLE_ID_LEN];
>>> + __u8 type;
>>> + acpi_probe_entry_validate_subtbl subtable_valid;
>>> + union {
>>> + acpi_tbl_table_handler probe_table;
>>> + acpi_tbl_entry_handler probe_subtbl;
>>> + };
>>
>> Could we avoid using union for probe_table & probe_subtbl? The benefit is
>> that we don't need to do function casting below and compiler can
>> automatically check the correctness.
>>
>>> + kernel_ulong_t driver_data;
>>> +};
>>> +
>>> +#define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid,
>>> data, fn) \
>>> + static const struct acpi_probe_entry __acpi_probe_##name \
>>> + __used __section(__##table##_acpi_probe_table) \
>>> + = { \
>>> + .id = table_id, \
>>> + .type = subtable, \
>>> + .subtable_valid = valid, \
>>> + .probe_table = (acpi_tbl_table_handler)fn, \
>>> + .driver_data = data, \
>>> + }
>>> +
>>
>> Something like:
>>
>> #define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid,
>> data, fn, subfn) \
>> static const struct acpi_probe_entry __acpi_probe_##name \
>> __used __section(__##table##_acpi_probe_table) \
>> = { \
>> .id = table_id, \
>> .type = subtable, \
>> .subtable_valid = valid, \
>> .probe_table = fn, \
>> .probe_subtbl = subfn, \
>> .driver_data = data, \
>> }
>>
>> Then in patch 3, you can define new entries as:
>>
>> IRQCHIP_ACPI_DECLARE(gic_v2, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
>> gic_validate_dist, ACPI_MADT_GIC_VERSION_V2,
>> NULL, gic_v2_acpi_init);
>> IRQCHIP_ACPI_DECLARE(gic_v2_maybe, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
>> gic_validate_dist, ACPI_MADT_GIC_VERSION_NONE,
>> NULL, gic_v2_acpi_init);
>>
>
> That's exactly what I was trying to avoid. If you want to do that, do
> it in the IRQCHIP_ACPI_DECLARE macro, as there is strictly no need for
> this this NULL to appear here (MADT always matches by subtable).
>
> Or even better, have two ACPI_DECLARE* that populate the probe entry in
> a mutually exclusive way (either probe_table is set and both
> valid/subtbl are NULL, or probe_table is NULL and the two other fields
> are set).
Yes, this approach would be sufficient. So users can clearly tell them
apart in terms of usage cases.
Thanks,
-Wei
>
> Thanks,
>
> M.
>
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