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 PCI_REPORT_PMCAP 9F "Aug 13, 1999"
 NAME
pci_report_pmcap - Report Power Management capability of a PCI device

 SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>



int pci_report_pmcap(dev_info_t *dip, int cap, void *arg);




 INTERFACE LEVEL
illumos DDI specific (illumos DDI)

 PARAMETERS
dip


Pointer to the device's dev_info structure



cap


Power management capability



arg


Argument for the capability




 DESCRIPTION
Some PCI devices provide power management capabilities in addition to those
provided by the PCI Power Management Specification. The
pci_report_pmcap() function reports those Power Management capabilities
of the PCI device to the framework. Framework supports dynamic changing of the
capability by allowing pci_report_pmcap() to be called multiple times.
Following are the supported capabilities as indicated by the cap:


PCI_PM_IDLESPEED \(em The PCI_PM_IDLESPEED value indicates the
lowest PCI clock speed that a device can tolerate when idle, and is applicable
only to 33 MHz PCI bus. arg represents the lowest possible idle speed in
KHz (1 KHz is 1000 Hz). The integer value representing the speed should be cast
to (void *)before passing as arg to pci_report_pmcap().


The special values of arg are:
PCI_PM_IDLESPEED_ANY


The device can tolerate any idle clock speed.



PCI_PM_IDLESPEED_NONE


The device cannot tolerate slowing down of PCI clock even when idle.





If the driver doesn't make this call, PCI_PM_IDLESPEED_NONE is assumed.
In this case, one offending device can keep the entire bus from being power
managed.

 RETURN VALUES
The pci_report_pmcap() function returns:
DDI_SUCCESS


Successful reporting of the capability



DDI_FAILURE


Failure to report capability because of invalid argument(s)




 CONTEXT
The pci_report_pmcap() function can be called from user, kernel and
interrupt context.

 EXAMPLES
1. A device driver knows that the device it controls works with any clock
between DC and 33 MHz as specified in Section 4.2.3.1: Clock Specification
 of the PCI Bus Specification Revision 2.1. The device driver makes
the following call from its attach(9E):

if (pci_report_pmcap(dip, PCI_PM_IDLESPEED, PCI_PM_IDLESPEED_ANY) !=
 DDI_SUCCESS)
 cmn_err(CE_WARN, "%s%d: pci_report_pmcap failed\en",
 ddi_driver_name(dip), ddi_get_instance(dip));





2. A device driver controls a 10/100 Mb Ethernet device which runs the device
state machine on the chip from the PCI clock. For the device state machine to
receive packets at 100 Mb, the PCI clock cannot drop below 4 MHz. The driver
makes the following call whenever it negotiates a 100 Mb Ethernet connection:

if (pci_report_pmcap(dip, PCI_PM_IDLESPEED, (void *)4000) !=
 DDI_SUCCESS)
 cmn_err(CE_WARN, "%s%d: pci_report_pmcap failed\en",
 ddi_driver_name(dip), ddi_get_instance(dip));




 ATTRIBUTES
See attributes(7) for descriptions of the following attributes:






ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Committed



 SEE ALSO
Writing Device Drivers


PCI Bus Power Management Interface Specification Version 1.1


PCI Bus Specification Revision 2.1