[RFC] ACPI/irq: Apply ACPI_IRQCHIP_FWSPEC_ARG0 only for GSI domain

[Shanker Donthineni]

Hi James,

The usage of an uninitialized variable in the PPTT code has resulted in another problem.
The MPAM driver probe fails when the variable "num_levels" contains a random value. The
code modification provided below resolves the issue. Please review it.

$ git diff drivers/acpi/pptt.c
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index 200a5f806d89..773334379fa4 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -1003,6 +1003,8 @@ int find_acpi_cache_level_from_id(u32 cache_id)
                 cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
                 if (!cpu_node)
                         break;
+
+               num_levels = 0;
                 acpi_count_levels(table, cpu_node, &num_levels, NULL);

                 for (level = 0; level <= num_levels; level++) {
@@ -1073,6 +1075,8 @@ int acpi_pptt_get_cpumask_from_cache_id(u32 cache_id, cpumask_t *cpus)
                 cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
                 if (!cpu_node)
                         break;
+
+               num_levels = 0;
                 acpi_count_levels(table, cpu_node, &num_levels, NULL);

                 for (level = 0; level <= num_levels; level++) {

-Shanker

On 5/31/23 21:33, Shanker Donthineni wrote:
> Hi James
> 
> When the IRQ combining feature is enabled, the following modification becomes
> necessary. Without implementing this change. The MPAM feature is not working on
> NVIDIA platforms.
> 
> Please review the code and provide feedback.
> 
> 
> On 4/28/23 11:58, Shanker Donthineni wrote:
>> The implementation of the updated GICv3 parameter parsing code in
>> pack_fwspec() is not compatible for the non-GSI drivers. It uses
>> the offset 1 for hardware IRQ, but the unmodified GPIO driver
>> expects the offset value to be 0, leading to a regression.
>>
>> This patch applies new mapping to the GSI driver only to fix
>> the issue.
>>
>> Signed-off-by: Shanker Donthineni <sdonthineni at nvidia.com>
>> ---
>>
>>   drivers/acpi/irq.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
>> index d4225d0b45d0..3d7f0643ed14 100644
>> --- a/drivers/acpi/irq.c
>> +++ b/drivers/acpi/irq.c
>> @@ -53,7 +53,8 @@ static void pack_fwspec(struct irq_fwspec *fwspec, u32 gsi, int trigger,
>>   {
>>       unsigned int offset = 0;
>> -    if (IS_ENABLED(CONFIG_ACPI_IRQCHIP_FWSPEC_ARG0)) {
>> +    if (IS_ENABLED(CONFIG_ACPI_IRQCHIP_FWSPEC_ARG0) &&
>> +        (fwspec->fwnode == acpi_get_gsi_domain_id(gsi))) {
>>           fwspec->param[0] = ACPI_IRQCHIP_FWSPEC_ARG0;
>>           offset = 1;
>>       }
>> @@ -216,8 +217,8 @@ static inline void acpi_irq_parse_one_match(struct fwnode_handle *fwnode,
>>       ctx->rc = 0;
>>       *ctx->res_flags = acpi_dev_irq_flags(triggering, polarity, shareable, wake_capable);
>> -    pack_fwspec(ctx->fwspec, hwirq, triggering, polarity);
>>       ctx->fwspec->fwnode = fwnode;
>> +    pack_fwspec(ctx->fwspec, hwirq, triggering, polarity);
>>   }
>>   /**