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From: "Marek Behún" <kabel@kernel.org>
To: Marc Zyngier <maz@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
Date: Mon, 10 Jan 2022 11:23:01 +0100	[thread overview]
Message-ID: <20220110112301.7e13c716@thinkpad> (raw)
In-Reply-To: <bf65af53fe1a4e6b814b124b59ad3aa9@kernel.org>

On Mon, 10 Jan 2022 09:28:39 +0000
Marc Zyngier <maz@kernel.org> wrote:

> 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.

Dear Marc,

That's why I put it as a last patch here :)

I have the questions

1) the first is that this driver has only ever been used on Armada 37xx,
   where there has always been only one PCIe controller, and it's name
   always was d0070000.pcie, so the irq_chip was always called
   d0070000.pcie-irq.
   So we could theoretically infer from config options if we are
   building for Armada 37xx: if ARM64 and ARMADA_37XX_CLK config options
   are enabled, make the name d0070000.pcie-irq, otherwise advk-INT ?

2) I tried to look for the name d0070000.pcie-irq in /proc and /sysfs,
   but couldn't find it there (not in /proc/interrupts nor anywhere
   else). It is possible that I omitted something, or that with other
   PCIe card it will show up when corresponding driver is loaded.
   But theoretically, if I could prove that until now this never
   appeared anywhere in sysfs for some reason, then we could change it,
   right? Becuase that way it isn't sysfs ABI change.

Thanks.

Marek

  reply	other threads:[~2022-01-10 10:23 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-10  1:49 [PATCH v2 00/23] PCI: aardvark controller fixes BATCH 4 Marek Behún
2022-01-10  1:49 ` [PATCH v2 01/23] PCI: aardvark: Replace custom PCIE_CORE_INT_* macros with PCI_INTERRUPT_* Marek Behún
2022-01-10 17:07   ` Bjorn Helgaas
2022-01-10  1:49 ` [PATCH v2 02/23] PCI: aardvark: Fix reading MSI interrupt number Marek Behún
2022-02-04 17:24   ` Lorenzo Pieralisi
2022-02-05 10:53     ` Marc Zyngier
2022-01-10  1:49 ` [PATCH v2 03/23] PCI: aardvark: Fix support for MSI interrupts Marek Behún
2022-01-10  1:49 ` [PATCH v2 04/23] PCI: aardvark: Rewrite IRQ code to chained IRQ handler Marek Behún
2022-01-10  1:50 ` [PATCH v2 05/23] PCI: aardvark: Check return value of generic_handle_domain_irq() when processing INTx IRQ Marek Behún
2022-01-10  1:50 ` [PATCH v2 06/23] PCI: aardvark: Make MSI irq_chip structures static driver structures Marek Behún
2022-01-10  1:50 ` [PATCH v2 07/23] PCI: aardvark: Make msi_domain_info structure a static driver structure Marek Behún
2022-01-10  1:50 ` [PATCH v2 08/23] PCI: aardvark: Use dev_fwnode() instead of of_node_to_fwnode(dev->of_node) Marek Behún
2022-01-10  1:50 ` [PATCH v2 09/23] PCI: aardvark: Refactor unmasking summary MSI interrupt Marek Behún
2022-01-10  1:50 ` [PATCH v2 10/23] PCI: aardvark: Add support for masking MSI interrupts Marek Behún
2022-01-10  1:50 ` [PATCH v2 11/23] PCI: aardvark: Fix setting MSI address Marek Behún
2022-02-17 17:14   ` Bjorn Helgaas
2022-02-18 14:43     ` Marek Behún
2022-02-23 18:13       ` Bjorn Helgaas
2022-02-24 12:59         ` Pali Rohár
2022-02-24 19:43           ` Bjorn Helgaas
2022-01-10  1:50 ` [PATCH v2 12/23] PCI: aardvark: Enable MSI-X support Marek Behún
2022-01-10  1:50 ` [PATCH v2 13/23] PCI: aardvark: Add support for ERR interrupt on emulated bridge Marek Behún
2022-01-10  1:50 ` [PATCH v2 14/23] PCI: aardvark: Fix reading PCI_EXP_RTSTA_PME bit " Marek Behún
2022-01-10  1:50 ` [PATCH v2 15/23] PCI: aardvark: Optimize writing PCI_EXP_RTCTL_PMEIE and PCI_EXP_RTSTA_PME " Marek Behún
2022-01-10  1:50 ` [PATCH v2 16/23] PCI: aardvark: Add support for PME interrupts Marek Behún
2022-01-10  1:50 ` [PATCH v2 17/23] PCI: aardvark: Fix support for PME requester on emulated bridge Marek Behún
2022-01-10  1:50 ` [PATCH v2 18/23] PCI: aardvark: Use separate INTA interrupt for emulated root bridge Marek Behún
2022-01-10  1:50 ` [PATCH v2 19/23] PCI: aardvark: Remove irq_mask_ack callback for INTx interrupts Marek Behún
2022-01-10  1:50 ` [PATCH v2 20/23] PCI: aardvark: Don't mask irq when mapping Marek Behún
2022-01-10  1:50 ` [PATCH v2 21/23] PCI: aardvark: Drop __maybe_unused from advk_pcie_disable_phy() Marek Behún
2022-01-10  1:50 ` [PATCH v2 22/23] PCI: aardvark: Update comment about link going down after link-up Marek Behún
2022-01-10  1:50 ` [PATCH v2 23/23] PCI: aardvark: Make main irq_chip structure a static driver structure Marek Behún
2022-01-10  9:28   ` Marc Zyngier
2022-01-10 10:23     ` Marek Behún [this message]
2022-01-10 10:53     ` Pali Rohár
2022-01-10 14:44       ` Marc Zyngier
2022-01-10 15:19         ` Marek Behún
2022-02-08 10:50 ` (subset) [PATCH v2 00/23] PCI: aardvark controller fixes BATCH 4 Lorenzo Pieralisi

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