| Message ID | 20160618180056.7267.67911.stgit@bhelgaas-glaptop2.roam.corp.google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Sat, Jun 18, 2016 at 01:00:56PM -0500, Bjorn Helgaas wrote: > The dev.pme_support field, pci_pm_init(), and pci_pme_capable() depend on > the fact that the pci_power_t values (PCI_D0, PCI_D1, etc.) match the > definition of the PME_Support field of the Power Management Capabilities > register in the Power Management capability (see PCI Bus Power Management > spec r1.2, sec 3.2.3). In addition, pci_power_t is assumed to match the power state in the PM Control and Status Register, see pci_raw_set_power_state(). The PMCSR reserves only 2 bits for the power state, so it can only represent D0 to D3hot. If the device is in D3cold, reads from its config space usually result in an "all ones" fabricated response. Thus D3hot and D3cold cannot be differentiated when reading the power state in the PMCSR, they're represented by the same value. Best regards, Lukas > > Add a note to this effect at the pci_power_t typedef. > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > --- > include/linux/pci.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8597b42..85cede3 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -101,6 +101,10 @@ enum { > DEVICE_COUNT_RESOURCE = PCI_NUM_RESOURCES, > }; > > +/* > + * pci_power_t values must match the bits in the PME_Support field of the > + * Power Management Capabilities register in the Power Management capability. > + */ > typedef int __bitwise pci_power_t; > > #define PCI_D0 ((pci_power_t __force) 0) > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, 2016-06-18 at 13:00 -0500, Bjorn Helgaas wrote: > The dev.pme_support field, pci_pm_init(), and pci_pme_capable() depend > on > the fact that the pci_power_t values (PCI_D0, PCI_D1, etc.) match the > definition of the PME_Support field of the Power Management > Capabilities > register in the Power Management capability (see PCI Bus Power > Management > spec r1.2, sec 3.2.3). Nice to know! Thanks. If it matters: Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Add a note to this effect at the pci_power_t typedef. > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > --- > include/linux/pci.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8597b42..85cede3 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -101,6 +101,10 @@ enum { > DEVICE_COUNT_RESOURCE = PCI_NUM_RESOURCES, > }; > > +/* > + * pci_power_t values must match the bits in the PME_Support field of > the > + * Power Management Capabilities register in the Power Management > capability. > + */ > typedef int __bitwise pci_power_t; > > #define PCI_D0 ((pci_power_t __force) 0) >
On Sat, Jun 18, 2016 at 01:00:56PM -0500, Bjorn Helgaas wrote: > The dev.pme_support field, pci_pm_init(), and pci_pme_capable() depend on > the fact that the pci_power_t values (PCI_D0, PCI_D1, etc.) match the > definition of the PME_Support field of the Power Management Capabilities > register in the Power Management capability (see PCI Bus Power Management > spec r1.2, sec 3.2.3). > > Add a note to this effect at the pci_power_t typedef. > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Good idea, Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/pci.h b/include/linux/pci.h index 8597b42..85cede3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -101,6 +101,10 @@ enum { DEVICE_COUNT_RESOURCE = PCI_NUM_RESOURCES, }; +/* + * pci_power_t values must match the bits in the PME_Support field of the + * Power Management Capabilities register in the Power Management capability. + */ typedef int __bitwise pci_power_t; #define PCI_D0 ((pci_power_t __force) 0)
The dev.pme_support field, pci_pm_init(), and pci_pme_capable() depend on the fact that the pci_power_t values (PCI_D0, PCI_D1, etc.) match the definition of the PME_Support field of the Power Management Capabilities register in the Power Management capability (see PCI Bus Power Management spec r1.2, sec 3.2.3). Add a note to this effect at the pci_power_t typedef. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> --- include/linux/pci.h | 4 ++++ 1 file changed, 4 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html