[PATCH] PCI: do not delay when changing power states on Geode

[PATCH] PCI: do not delay when changing power states on Geode

[Andres Salomon]

Geode hardware requires no delay when doing power transition for PCI;
the board doesn't even have a real PCI bus.  Thanks to Tom Sylla for
pointing this out.  We can save precious milliseconds when changing power
states to D3hot by getting rid of this delay.

We do this as a PCI quirk.

Signed-off-by: Andres Salomon <dilinger@debian.org>
---

 drivers/pci/quirks.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 01d8f8a..b85fd5f 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -1368,6 +1368,20 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	0x260a, quirk_intel_pcie_pm);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	0x260b, quirk_intel_pcie_pm);
 
 /*
+ * Geode hardware does not require any sort of delay when
+ * transitioning between PCI power states.  This allows us to shave
+ * off time when doing suspend/resume.
+ */
+static void __init quirk_geode_pci_pm(struct pci_dev *dev)
+{
+	pci_pm_d3_delay = 0;
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY,
+		quirk_geode_pci_pm);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA,
+		quirk_geode_pci_pm);
+
+/*
  * Toshiba TC86C001 IDE controller reports the standard 8-byte BAR0 size
  * but the PIO transfers won't work if BAR0 falls at the odd 8 bytes.
  * Re-allocate the region if needed...

Re: [PATCH] PCI: do not delay when changing power states on Geode

[Alan Cox]

On Thu, 5 Jul 2007 22:13:51 -0400
Andres Salomon <dilinger@queued.net> wrote:

> Geode hardware requires no delay when doing power transition for PCI;
> the board doesn't even have a real PCI bus.  Thanks to Tom Sylla for
> pointing this out.  We can save precious milliseconds when changing power
> states to D3hot by getting rid of this delay.
> 
> We do this as a PCI quirk.

NAK

These systems may have other components on them which require the proper
transition times and the CS5530 supports external real PCI devices.

Alan

Re: UNS: Re: [PATCH] PCI: do not delay when changing power states on Geode

[Andres Salomon]

On Fri, 6 Jul 2007 11:05:18 +0100
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> On Thu, 5 Jul 2007 22:13:51 -0400
> Andres Salomon <dilinger@queued.net> wrote:
> 
> > Geode hardware requires no delay when doing power transition for PCI;
> > the board doesn't even have a real PCI bus.  Thanks to Tom Sylla for
> > pointing this out.  We can save precious milliseconds when changing power
> > states to D3hot by getting rid of this delay.
> > 
> > We do this as a PCI quirk.
> 
> NAK
> 
> These systems may have other components on them which require the proper
> transition times and the CS5530 supports external real PCI devices.
> 
> Alan

You're right; I munged the description.  Turns out the patch is wrong
anyways, though (whether the delay is necessary or not turns out to be
firmware dependent).


-- 
Andres Salomon <dilinger@queued.net>