linux-kernel - Re: [PATCH v2 03/22] MSI: Remove the redundant irq_set_chip

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Date:	Fri, 26 Sep 2014 10:04:45 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Xinwei Hu <huxinwei@...wei.com>,
	Wuyun <wuyun.wu@...wei.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	<linux-arch@...r.kernel.org>, <arnab.basu@...escale.com>,
	<Bharat.Bhushan@...escale.com>, <x86@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
	<xen-devel@...ts.xenproject.org>, Joerg Roedel <joro@...tes.org>,
	<iommu@...ts.linux-foundation.org>, <linux-mips@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-s390@...r.kernel.org>,
	Sebastian Ott <sebott@...ux.vnet.ibm.com>,
	"Tony Luck" <tony.luck@...el.com>, <linux-ia64@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	<sparclinux@...r.kernel.org>, Chris Metcalf <cmetcalf@...era.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Lucas Stach <l.stach@...gutronix.de>,
	David Vrabel <david.vrabel@...rix.com>,
	"Sergei Shtylyov" <sergei.shtylyov@...entembedded.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Subject: Re: [PATCH v2 03/22] MSI: Remove the redundant irq_set_chip_data()

On 2014/9/25 15:19, Thierry Reding wrote:
> On Thu, Sep 25, 2014 at 11:14:13AM +0800, Yijing Wang wrote:
>> Currently, pcie-designware, pcie-rcar, pci-tegra drivers
>> use irq chip_data to save the msi_chip pointer. They
>> already call irq_set_chip_data() in their own MSI irq map
>> functions. So irq_set_chip_data() in arch_setup_msi_irq()
>> is useless.
> 
> Again, I think this should be the other way around. If drivers do
> something that's already handled by the core, then the duplicate code
> should be dropped from the drivers.

Hi Thierry, this is different thing, because chip_data is specific to IRQ
controller, and in other platform, like in x86, chip_data is used to save irq_cfg.
So we can not call irq_set_chip_data() in core code.

x86 irq piece code

int arch_setup_hwirq(unsigned int irq, int node)
{
	struct irq_cfg *cfg;
	unsigned long flags;
	int ret;

	cfg = alloc_irq_cfg(irq, node);
	if (!cfg)
		return -ENOMEM;

	raw_spin_lock_irqsave(&vector_lock, flags);
	ret = __assign_irq_vector(irq, cfg, apic->target_cpus());
	raw_spin_unlock_irqrestore(&vector_lock, flags);

	if (!ret)
		irq_set_chip_data(irq, cfg);  ------------->Save irq_cfg
	else
		free_irq_cfg(irq, cfg);
	return ret;
}

Thanks!
Yijing.

> 
> Thierry
> 


-- 
Thanks!
Yijing

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