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On Fri, Oct 13, 2006 at 10:26:08PM -0700, Andrew Morton wrote: > On Tue, 10 Oct 2006 07:38:17 -0600 > Matthew Wilcox <matthew@wil.cx> wrote: > > > Section 5.3 of PCI Bus Power Management 1.2 states: > > > > There is a minimum recovery time requirement of 200 ?s between when > > a function is programmed from D2 to D0 and when the function can be > > next accessed as a target (including PCI configuration accesses). If > > an access is attempted in violation of the specified minimum recovery > > time, undefined system behavior may result. > > > > We have to prevent the user running lspci during this time, and > > fortunately we already have the pci_block_user_cfg_access() API to > > do this. > > > > Signed-off-by: Matthew Wilcox <matthew@wil.cx> > > --- > > drivers/pci/pci.c | 8 ++++++++ > > 1 files changed, 8 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > index a544997..1bb059a 100644 > > --- a/drivers/pci/pci.c > > +++ b/drivers/pci/pci.c > > @@ -366,6 +366,11 @@ pci_set_power_state(struct pci_dev *dev, > > break; > > } > > > > + /* We have to prevent accesses to config space while transitioning > > + * between power states > > + */ > > + pci_block_user_cfg_access(dev); > > + > > /* enter specified state */ > > pci_write_config_word(dev, pm + PCI_PM_CTRL, pmcsr); > > > > @@ -383,6 +388,9 @@ pci_set_power_state(struct pci_dev *dev, > > if (platform_pci_set_power_state) > > platform_pci_set_power_state(dev, state); > > > > + /* Should be safe to allow userspace access to the device again now */ > > + pci_unblock_user_cfg_access(dev); > > + > > dev->current_state = state; > > > > /* According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT > > This patch independently causes the same failure: the Vaio doesn't power > off after suspend-to-disk and after a manual power cycle and resume, > networking is dead. > > The message `acpi_power_off called' never comes out, so something probably > got stuck. > > Or maybe something failed somewhere and the error code which would have > helped us solve this bug was simply ignored. > > > > Note that pci_block_user_cfg_access() calls pci_save_state(), which can > fail. But pci_block_user_cfg_access() discards that information and > returns void. If this happens, userspace config space reads will return... > what? There is a thread right now on the linux-pm mailing list about how this patch is wrong. I'm going to drop it right now... thanks, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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