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From: Thomas Gleixner <tglx@linutronix.de>
To: Jiang Liu <jiang.liu@linux.intel.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Lv Zheng <lv.zheng@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
	"x86 @ kernel . org" <x86@kernel.org>
Subject: Re: [RFC 2/4] PCI, MSI: Optionally free legacy PCI IRQ when enabling MSI/MSI-X
Date: Fri, 15 May 2015 23:02:59 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.11.1505152259480.4225@nanos> (raw)
In-Reply-To: <1430968374-29286-3-git-send-email-jiang.liu@linux.intel.com>

On Thu, 7 May 2015, Jiang Liu wrote:

> Once PCI MSI/MSI-X is enabled by the device driver, PCI device won't
> make use of legacy PCI IRQ until PCI MSI/MSI-X is disabled again.
> So optionally free legacy PCI IRQ when enabling MSI/MSI-X and reallocate
> when disabling MSI/MSI-X.

This is a bit odd. With your proposed change we'll have:

     alloc_legacy_irq()

     msi[x]_enable()
	free_legacy_irq()

     msi[x]_disable()
	alloc_legacy_irq()

And after that we shut down the device which will free the legacy irq
again.

Shouldn't we allocate the legacy irq only if we really need it?

Thanks,

	tglx

  reply	other threads:[~2015-05-15 21:02 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-07  3:12 [RFC 0/4] Introduce a mechanism to allocate PCI IRQ on demand Jiang Liu
2015-05-07  3:12 ` [RFC 1/4] PCI: Add hooks to allocate/free IRQ resources when binding/unbinding driver Jiang Liu
2015-05-19 14:45   ` Bjorn Helgaas
2015-05-07  3:12 ` [RFC 2/4] PCI, MSI: Optionally free legacy PCI IRQ when enabling MSI/MSI-X Jiang Liu
2015-05-15 21:02   ` Thomas Gleixner [this message]
2015-05-20  3:06     ` Jiang Liu
2015-05-20  7:47       ` Thomas Gleixner
2015-05-19 15:08   ` Bjorn Helgaas
2015-05-19 15:16     ` Michael S. Tsirkin
2015-05-19 15:26       ` Michael S. Tsirkin
2015-05-20  3:07         ` Jiang Liu
2015-05-19 21:39   ` Bjorn Helgaas
2015-05-20  3:12     ` Jiang Liu
2015-05-07  3:12 ` [RFC 3/4] PCI, x86: Allocate PCI IRQ on demand and free it when not used anymore Jiang Liu
2015-05-07  3:12 ` [RFC 4/4] PCI: Introduce helpers to manage pci_dev->irq and pci_dev->irq_managed Jiang Liu
2015-05-19 13:35 ` [RFC 0/4] Introduce a mechanism to allocate PCI IRQ on demand Thomas Gleixner
2015-05-20  3:21   ` Jiang Liu

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