From: "John W. Linville" <linville@tuxdriver.com>
To: Adam Belay <ambx1@neo.rr.com>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
linux-pm@lists.osdl.org, linux-kernel@vger.kernel.org,
greg@kroah.com, grundler@parisc-linux.org,
linux-pci@atrey.karlin.mff.cuni.cz, rmk+lkml@arm.linux.org.uk,
matthew@wil.cx, "David S. Miller" <davem@davemloft.net>
Subject: Re: [patch 2.6.13-rc2] pci: restore BAR values from pci_set_power_state for D3hot->D0
Date: Wed, 13 Jul 2005 13:34:21 -0400 [thread overview]
Message-ID: <20050713173417.GA21547@tuxdriver.com> (raw)
In-Reply-To: <20050712022855.GA3689@neo.rr.com>
On Mon, Jul 11, 2005 at 10:28:55PM -0400, Adam Belay wrote:
> On Fri, Jul 08, 2005 at 02:34:56PM -0400, John W. Linville wrote:
> > Some firmware leaves devices in D3hot after a (re)boot. Most drivers
> > call pci_enable_device very early, so devices left in D3hot that lose
> > configuration during the D3hot->D0 transition will be inaccessible to
> > their drivers.
>
> Also, I think there is a possibility of only enabling boot devices for ACPI
> S4. However, for the reboot case, we're not restoring anything. Instead new
> resource assignments are being made. Doesn't the PCI subsystem already
> handle this?
I'm not sure I understand you...the kernel doesn't actually make the
assignments, relying on the BIOS to do so...am I wrong?
So, if the BIOS leaves a device in D3hot, it will loose it's
BIOS-assigned resources when it transitions to D0 in pci_enable_device.
The point of this patch is to restore those BAR assignments so that
the device's registers will be accessible to the driver. The driver
remains blissfully unaware of the D3hot->D0 issue.
> > * pci_set_power_state - Set the power state of a PCI device
> > * @dev: PCI device to be suspended
> > * @state: PCI power state (D0, D1, D2, D3hot, D3cold) we're entering
> > @@ -239,7 +270,7 @@ pci_find_parent_resource(const struct pc
> > int
> > pci_set_power_state(struct pci_dev *dev, pci_power_t state)
> > {
>
> Couldn't this be in pci_restore_state() instead? I was thinking it would
> (in part) replace the ugly dword reads we have now. They include many
> registers we don't need to touch. I wonder if we'll need pci_save_state()
> at all or if we can derive all the information from the pci_dev. I'll have
> to look into it further.
Currently pci_restore_state is only useful if there is a preceding
pci_save_state. While this commonly occurs in the ->resume routines,
most drivers don't do any such thing (i.e. either save or restore) in
the ->probe routines. This is likely because it only makes sense to
do so if you know about the D3hot->D0 issue; in that case, we would
be back to replicating code in any number of drivers. I think we
agree that should be avoided.
> Also we need a way to restore specific PCI capabilities.
If you are asking for additional patches (or more changes to this one)
then you'll have to be more specific. I don't know what you want here.
Thanks,
John
--
John W. Linville
linville@tuxdriver.com
next prev parent reply other threads:[~2005-07-13 17:39 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-23 19:14 [RFC] firmware leaves device in D3hot at boot John W. Linville
2005-06-24 2:28 ` John W. Linville
2005-06-30 17:10 ` Greg KH
2005-07-01 1:41 ` John W. Linville
2005-07-01 2:26 ` [patch 2.6.12] pci: restore BAR values in pci_enable_device John W. Linville
2005-07-01 2:26 ` [patch 2.6.12 (repost w/ corrected subject)] pci: restore BAR values in pci_enable_device_bars John W. Linville
2005-07-02 7:29 ` Grant Grundler
2005-07-02 8:09 ` Russell King
2005-07-05 20:05 ` Matthew Wilcox
2005-07-05 21:46 ` Russell King
2005-07-05 23:34 ` Ivan Kokshaysky
2005-07-06 7:46 ` Russell King
2005-07-08 0:57 ` John W. Linville
2005-07-08 0:59 ` [patch 2.6.13-rc2] pci: restore BAR values in pci_set_power_state for D3hot->D0 John W. Linville
2005-07-08 3:43 ` [linux-pm] " david-b
2005-07-08 12:37 ` John W. Linville
2005-07-08 3:11 ` [patch 2.6.12 (repost w/ corrected subject)] pci: restore BAR values in pci_enable_device_bars David S. Miller
2005-07-08 5:51 ` Ivan Kokshaysky
2005-07-08 6:35 ` David S. Miller
2005-07-08 7:03 ` Ivan Kokshaysky
2005-07-08 7:33 ` David S. Miller
2005-07-08 8:20 ` Ivan Kokshaysky
2005-07-08 18:34 ` [patch 2.6.13-rc2] pci: restore BAR values from pci_set_power_state for D3hot->D0 John W. Linville
2005-07-08 19:08 ` David S. Miller
2005-07-10 17:53 ` Ivan Kokshaysky
2005-07-11 12:48 ` Lennert Buytenhek
2005-07-11 13:15 ` John W. Linville
2005-07-11 13:19 ` [patch 2.6.13-rc2] PCI: Add symbol exports for pci_restore_bars John W. Linville
2005-07-11 17:18 ` Greg KH
2005-07-11 17:36 ` John W. Linville
2005-07-11 17:38 ` [patch 2.6.13-rc2] PCI: Add GPL symbol export " John W. Linville
2005-07-12 2:28 ` [patch 2.6.13-rc2] pci: restore BAR values from pci_set_power_state for D3hot->D0 Adam Belay
2005-07-13 17:34 ` John W. Linville [this message]
2005-07-26 23:49 ` Greg KH
2005-07-27 1:36 ` John W. Linville
2005-07-27 14:12 ` John W. Linville
2005-07-27 14:19 ` [patch 2.6.13-rc3] pci: restore BAR values after D3hot->D0 for devices that need it John W. Linville
2005-07-31 19:36 ` Ralf Baechle
2005-08-02 17:31 ` Greg KH
2005-08-02 16:41 ` Jesse Brandeburg
2005-09-14 13:52 ` [patch 2.6.14-rc1] pci: only call pci_restore_bars at boot John W. Linville
2005-09-14 15:08 ` Jeff Garzik
2005-09-14 16:26 ` David S. Miller
2005-09-14 16:47 ` John W. Linville
2005-09-14 18:22 ` Ivan Kokshaysky
2005-07-05 17:46 ` [patch 2.6.12 (repost w/ corrected subject)] pci: restore BAR values in pci_enable_device_bars John W. Linville
2005-07-18 12:17 ` Grant Grundler
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