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From: Jeff Garzik <jgarzik@pobox.com>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Grant Grundler <grundler@parisc-linux.org>,
	Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
	Andrew Morton <akpm@osdl.org>, Greg KH <greg@kroah.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-pci@atrey.karlin.mff.cuni.cz
Subject: Re: [PATCH 0/4] PCI legacy I/O port free driver (take4)
Date: Thu, 02 Mar 2006 13:12:35 -0500
Message-ID: <44073593.60703@pobox.com> (raw)
In-Reply-To: <20060302180025.GC28895@flint.arm.linux.org.uk>

Russell King wrote:
> It's not really "I/O port resource allocation" though - the resources
> have already been allocated and potentially programmed into the BARs
> well before the driver gets anywhere near the device.
[...]
> Are you implying that somehow resources are allocated at pci_enable_device
> time?  If so, shouldn't we be thinking of moving completely to that model
> rather than having yet-another-pci-setup-model.

Actually, that's has been the rule ever since the cardbus days: 
resources -- bars and irqs -- should not be considered allocated until 
after pci_enable_device().

Documentation/pci.txt reflects this reality as well:

> 3. Enabling and disabling devices
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    Before you do anything with the device you've found, you need to enable
> it by calling pci_enable_device() which enables I/O and memory regions of
> the device, allocates an IRQ if necessary, assigns missing resources if
> needed and wakes up the device if it was in suspended state. Please note
> that this function can fail.

Any PCI driver that presumes -anything- about resources before calling 
pci_enable_device() is buggy, and that's been the case for many years. 
Some platform-specific PCI drivers violate this with special knowledge, 
but overall that's the rule.

Regards,

	Jeff



  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-02 15:12 Kenji Kaneshige
2006-03-02 15:14 ` [PATCH 1/4] PCI legacy I/O port free driver (take4) - Add no_ioport flag into pci_dev Kenji Kaneshige
2006-03-02 15:16 ` [PATCH 2/4] PCI legacy I/O port free driver (take4) - Update Documentation/pci.txt Kenji Kaneshige
2006-03-02 15:18 ` [PATCH 3/4] PCI legacy I/O port free driver (take4) - Make Intel e1000 driver legacy I/O port free Kenji Kaneshige
2006-03-02 15:20 ` [PATCH 4/4] PCI legacy I/O port free driver (take4) - Make Emulex lpfc " Kenji Kaneshige
2006-03-02 15:50 ` [PATCH 0/4] PCI legacy I/O port free driver (take4) Russell King
2006-03-02 16:23   ` Kenji Kaneshige
2006-03-02 16:41     ` Greg KH
2006-03-02 17:24   ` Grant Grundler
2006-03-02 18:00     ` Russell King
2006-03-02 18:12       ` Jeff Garzik [this message]
2006-03-02 19:13         ` Russell King
2006-03-02 20:01           ` Jeff Garzik
2006-03-02 19:23       ` Grant Grundler
2006-03-02 19:34     ` Russell King
2006-03-02 19:50       ` Roland Dreier
2006-03-03  3:17       ` Kenji Kaneshige
2006-03-03  6:59         ` Kenji Kaneshige
2006-03-06  1:38           ` Kenji Kaneshige
2006-03-10  2:10       ` Adam Belay
2006-03-10  4:10         ` Kenji Kaneshige
2006-03-10  7:49           ` Russell King
2006-03-10  8:33         ` Russell King
2006-03-13  5:47           ` Kenji Kaneshige

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