Re: [PATCH v3 3/5] irqchip/gic-v3-its: Split allocation from initialisation of its_node

[Dominic Rath <dominic.rath@ibv-augsburg.net>]

On Tue, Oct 24, 2023 at 11:18:21AM +0100, Marc Zyngier wrote:
> Yeah, that's clearly a regression, and I've confirmed it on my
> Synquacer (which means the TI folks have accurately copied a dumb
> idea). Can you please give the patch below a go on your system and
> confirm asap whether it works for you?
> 

Thanks a lot, with that patch applied on top of 6.6-rc6 MSI-X interrupts
work again for the AM64x.

Best Regards,

Dominic

> > I have no idea whether TI's use of this quirk was "correct", but it did
> > work, and since 6.6-rc6 MSI-X has been broken for us.
> 
> Just as for bad SW, the worse HW ideas get replicated. Then I write
> bad SW for it.
> 
> Thanks,
> 
> 	M.
> 
> From b5571a69f09733ecfa0c944cc48baced6590d024 Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <maz@kernel.org>
> Date: Tue, 24 Oct 2023 11:07:34 +0100
> Subject: [PATCH] irqchip/gic-v3-its: Don't override quirk settings with
>  default values
> 
> When splitting the allocation of the ITS node from its configuration,
> some of the default settings were kept in the latter instead of
> being moved to the former.
> 
> This has the side effect of negating some of the quirk detection that
> have happened in between, amongst which the dreaded Synquacer hack
> (that also affect Dominic's TI platform).
> 
> Move the initialisation of these fields early, so that they can
> again be overriden by the Synquacer quirk.
> 
> Fixes: 9585a495ac93 ("irqchip/gic-v3-its: Split allocation from initialisation of its_node")
> Reported by: Dominic Rath <dominic.rath@ibv-augsburg.net>
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Tested-by: Dominic Rath <dominic.rath@ibv-augsburg.net>

> Link: https://lore.kernel.org/r/20231024084831.GA3788@JADEVM-DRA
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 75a2dd550625..a8c89df1a997 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -5112,8 +5112,6 @@ static int __init its_probe_one(struct its_node *its)
>  	}
>  	its->cmd_base = (void *)page_address(page);
>  	its->cmd_write = its->cmd_base;
> -	its->get_msi_base = its_irq_get_msi_base;
> -	its->msi_domain_flags = IRQ_DOMAIN_FLAG_ISOLATED_MSI;
>  
>  	err = its_alloc_tables(its);
>  	if (err)
> @@ -5362,6 +5360,8 @@ static struct its_node __init *its_node_init(struct resource *res,
>  	its->typer = gic_read_typer(its_base + GITS_TYPER);
>  	its->base = its_base;
>  	its->phys_base = res->start;
> +	its->get_msi_base = its_irq_get_msi_base;
> +	its->msi_domain_flags = IRQ_DOMAIN_FLAG_ISOLATED_MSI;
>  
>  	its->numa_node = numa_node;
>  	its->fwnode_handle = handle;
> -- 
> 2.39.2
> 
> 
> -- 
> Without deviation from the norm, progress is not possible.