Re: [PATCH v3 3/3] PCI: dwc: Enable MSI affinity support

[Jon Hunter <jonathanh@nvidia.com>]

Hi Thomas,

On 27/01/2026 13:34, Thomas Gleixner wrote:
> On Tue, Jan 27 2026 at 11:30, Thomas Gleixner wrote:
>> The below untested hack should confirm that theory.
> 
> Actually looking at it deeper the solution is trivial because in this
> case writing the MSI message to the device is not required when the
> affinity changes because the message does not change. It is set once via
> msi_domain_activate() and stays the same for the life time of the
> interrupt.
> 
> So the below prevents the invocation of irq_chip_write_msi_msg() in
> msi_domain_set_affinity(), but I would recommend to investigate the
> actual underlying problem nevertheless:
> 
> It is going to roar its ugly head at some other place sooner than later
> as there are tons of other places which guard against
> pci_dev::current_state != PCI_D0.
> 
> Thanks,
> 
>          tglx
> ---
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -1495,7 +1495,7 @@ int irq_chip_redirect_set_affinity(struc
>   	WRITE_ONCE(redir->target_cpu, cpumask_first(dest));
>   	irq_data_update_effective_affinity(data, dest);
>   
> -	return IRQ_SET_MASK_OK;
> +	return IRQ_SET_MASK_OK_DONE;
>   }
>   EXPORT_SYMBOL_GPL(irq_chip_redirect_set_affinity);
>   #endif
> 

Yes that does fix it!

Tested-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!
Jon

-- 
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