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SubjectRe: [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI irq domain
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Hi Jason,

On 7/21/2020 9:13 AM, Jason Gunthorpe wrote:
> On Tue, Jul 21, 2020 at 09:02:28AM -0700, Dave Jiang wrote:
>> From: Megha Dey <megha.dey@intel.com>
>>
>> Add support for the creation of a new DEV_MSI irq domain. It creates a
>> new irq chip associated with the DEV_MSI domain and adds the necessary
>> domain operations to it.
>>
>> Add a new config option DEV_MSI which must be enabled by any
>> driver that wants to support device-specific message-signaled-interrupts
>> outside of PCI-MSI(-X).
>>
>> Lastly, add device specific mask/unmask callbacks in addition to a write
>> function to the platform_msi_ops.
>>
>> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: Megha Dey <megha.dey@intel.com>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> arch/x86/include/asm/hw_irq.h | 5 ++
>> drivers/base/Kconfig | 7 +++
>> drivers/base/Makefile | 1
>> drivers/base/dev-msi.c | 95 +++++++++++++++++++++++++++++++++++++++++
>> drivers/base/platform-msi.c | 45 +++++++++++++------
>> drivers/base/platform-msi.h | 23 ++++++++++
>> include/linux/msi.h | 8 +++
>> 7 files changed, 168 insertions(+), 16 deletions(-)
>> create mode 100644 drivers/base/dev-msi.c
>> create mode 100644 drivers/base/platform-msi.h
>>
>> diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
>> index 74c12437401e..8ecd7570589d 100644
>> +++ b/arch/x86/include/asm/hw_irq.h
>> @@ -61,6 +61,11 @@ struct irq_alloc_info {
>> irq_hw_number_t msi_hwirq;
>> };
>> #endif
>> +#ifdef CONFIG_DEV_MSI
>> + struct {
>> + irq_hw_number_t hwirq;
>> + };
>> +#endif
>
> Why is this in this patch? I didn't see an obvious place where it is
> used?

Since I have introduced the DEV-MSI domain and related ops, this is
required in the dev_msi_set_hwirq and dev_msi_set_desc in this patch.

>>
>> +static void __platform_msi_desc_mask_unmask_irq(struct msi_desc *desc, u32 mask)
>> +{
>> + const struct platform_msi_ops *ops;
>> +
>> + ops = desc->platform.msi_priv_data->ops;
>> + if (!ops)
>> + return;
>> +
>> + if (mask) {
>> + if (ops->irq_mask)
>> + ops->irq_mask(desc);
>> + } else {
>> + if (ops->irq_unmask)
>> + ops->irq_unmask(desc);
>> + }
>> +}
>> +
>> +void platform_msi_mask_irq(struct irq_data *data)
>> +{
>> + __platform_msi_desc_mask_unmask_irq(irq_data_get_msi_desc(data), 1);
>> +}
>> +
>> +void platform_msi_unmask_irq(struct irq_data *data)
>> +{
>> + __platform_msi_desc_mask_unmask_irq(irq_data_get_msi_desc(data), 0);
>> +}
>
> This is a bit convoluted, just call the op directly:
>
> void platform_msi_unmask_irq(struct irq_data *data)
> {
> const struct platform_msi_ops *ops = desc->platform.msi_priv_data->ops;
>
> if (ops->irq_unmask)
> ops->irq_unmask(desc);
> }
>

Sure, I will update this.

>> diff --git a/include/linux/msi.h b/include/linux/msi.h
>> index 7f6a8eb51aca..1da97f905720 100644
>> +++ b/include/linux/msi.h
>> @@ -323,9 +323,13 @@ enum {
>>
>> /*
>> * platform_msi_ops - Callbacks for platform MSI ops
>> + * @irq_mask: mask an interrupt source
>> + * @irq_unmask: unmask an interrupt source
>> * @write_msg: write message content
>> */
>> struct platform_msi_ops {
>> + unsigned int (*irq_mask)(struct msi_desc *desc);
>> + unsigned int (*irq_unmask)(struct msi_desc *desc);
>
> Why do these functions return things if the only call site throws it
> away?

Hmmm, fair enough, I will change it to void.

>
> Jason
>

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