linux-kernel - Re: [PATCH v3 14/24] genirq/gic-v3-mbi: Remove unused wired MSI mechanics

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Message-ID: <86h6drk9h1.wl-maz@kernel.org>
Date: Mon, 17 Jun 2024 14:03:06 +0100
From: Marc Zyngier <maz@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Shivamurthy Shastri
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Subject: Re: [PATCH v3 14/24] genirq/gic-v3-mbi: Remove unused wired MSI mechanics

On Mon, 17 Jun 2024 13:55:24 +0100,
Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> On Sat, Jun 15 2024 at 18:24, Marc Zyngier wrote:
> > On Fri, 14 Jun 2024 11:23:53 +0100,
> > Shivamurthy Shastri <shivamurthy.shastri@...utronix.de> wrote:
> >>  static struct msi_domain_info mbi_pmsi_domain_info = {
> >> -	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> >> -		   MSI_FLAG_LEVEL_CAPABLE),
> >> +	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
> >>  	.ops	= &mbi_pmsi_ops,
> >>  	.chip	= &mbi_pmsi_irq_chip,
> >>  };
> >
> > This patch doesn't do what it says. It simply kills any form of level
> > MSI support for *endpoints*, and has nothing to do with any sort of
> > "wire to MSI".
> >
> > What replaces it?
> 
> Patch 9/24 switches the wire to MSI with level support over. This just
> removes the leftovers.

That's not what I read.

Patch 9/24 rewrites the mbigen driver. Which has nothing to do with
what the gic-v3-mbi code does. They are different blocks, and the sole
machine that has the mbigen IP doesn't have any gic-v3-mbi support.
All they have in common are 3 random letters.

What you are doing here is to kill any support for *devices* that need
to signal level-triggered MSIs in that driver, and nothing to do with
wire-MSI translation.

So what replaces it?

	M.

-- 
Without deviation from the norm, progress is not possible.