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Date:   Mon, 10 Jan 2022 09:28:39 +0000
From:   Marc Zyngier <maz@kernel.org>
To:     =?UTF-8?Q?Marek_Beh=C3=BAn?= <kabel@kernel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <helgaas@kernel.org>, pali@kernel.org,
        linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 23/23] PCI: aardvark: Make main irq_chip structure a
 static driver structure
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 <20220110015018.26359-24-kabel@kernel.org>
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On 2022-01-10 01:50, Marek Behún wrote:
> Marc Zyngier says [1] that we should use struct irq_chip as a global
> static struct in the driver. Even though the structure currently
> contains a dynamic member (parent_device), Marc says [2] that he plans
> to kill it and make the structure completely static.
> 
> We have already converted others irq_chip structures in this driver in
> this way, but we omitted this one because the .name member is
> dynamically created from device's name, and the name is displayed in
> sysfs, so changing it would break sysfs ABI.
> 
> The rationale for changing the name (to "advk-INT") in spite of sysfs
> ABI, and thus allowing to convert to a static structure, is that after
> the other changes we made in this series, the IRQ chip is basically
> something different: it no logner generates ERR and PME interrupts 
> (they
> are generated by emulated bridge's rp_irq_chip).

There is no 'is spite of the ABI'. If you don't understand why
we don't break the ABI, you have an even bigger problem.

So NAK to this patch, now and forever. Any change to the structure to
make it read-only must allow the preservation of the existing names
when they are generated by the driver.

         M.
-- 
Jazz is not dead. It just smells funny...