lkml.org 
[lkml]   [2007]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] kexec: fix pci device initialization fail after kexec (2.6.23-rc2). (Related to e1000 doesn't resume properly from standby)
Date
On Monday, 6 August 2007 17:50, Joonwoo Park wrote:
> 2007/8/6, Rafael J. Wysocki <rjw@sisk.pl>:
> > On Monday, 6 August 2007 15:42, Joonwoo Park wrote:
> > > Hi.
> > > I think that the pci_set_power_state() has bug.
> > > The specification says that some delays is required.
> >
> > And they are in place, AFAICS (from drivers/pci/pci.c):
> >
> > /* Mandatory power management transition delays */
> > /* see PCI PM 1.1 5.6.1 table 18 */
> > if (state == PCI_D3hot || dev->current_state == PCI_D3hot)
> > msleep(pci_pm_d3_delay);
> > else if (state == PCI_D2 || dev->current_state == PCI_D2)
> > udelay(200);
> >
>
> The problem is occurred when state is 'PCI_D0', so those codes can't cover it.
> But pci pm specification 5.4.1 says that when programmed to D0 the
> equivalent of a warm reset, delay for the duration of the D3hot to D0
> Uninitialized state
> transition (10ms) to pci signal drivers remain disabled is required.

Section 5.4.1 of PCI PM 1.1. spec is about D3_hot. Specifically, it says
that if a device in D3_hot is programmed to D0, it performs the equivalent of
a warm reset. IOW, this is supposed to happen if the current state is D3_hot
and the targed state is D0, which is covered by the code snippet above.

Greetings,
Rafael


--
"Premature optimization is the root of all evil." - Donald Knuth
-
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/

\
 
 \ /
  Last update: 2007-08-06 20:41    [W:0.094 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site