[PATCH 8/9] PCI PM: clear IO and MEM when disabling a device

[PATCH 8/9] PCI PM: clear IO and MEM when disabling a device

[Adam Belay]

This patch modifies pci_disable_device() to clear IO and MEM from the
COMMAND PCI config register.  This is required before entering D3,  but
also probably a good general practice for system suspend.

Signed-off-by: Adam Belay <abelay@novell.com>

---
 pci.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff -urN a/drivers/pci/pci.c b/drivers/pci/pci.c
--- a/drivers/pci/pci.c	2006-05-31 20:40:25.000000000 -0400
+++ b/drivers/pci/pci.c	2006-06-04 15:09:16.000000000 -0400
@@ -312,8 +312,12 @@
 	u16 pci_command;
 	
 	pci_read_config_word(dev, PCI_COMMAND, &pci_command);
-	if (pci_command & PCI_COMMAND_MASTER) {
-		pci_command &= ~PCI_COMMAND_MASTER;
+	if (pci_command & (PCI_COMMAND_MASTER |
+			   PCI_COMMAND_IO |
+			   PCI_COMMAND_MEMORY)) {
+		pci_command &= ~ (PCI_COMMAND_MASTER |
+				  PCI_COMMAND_IO |
+				  PCI_COMMAND_MEMORY);
 		pci_write_config_word(dev, PCI_COMMAND, pci_command);
 	}
 	dev->is_busmaster = 0;

Re: [PATCH 8/9] PCI PM: clear IO and MEM when disabling a device

[Rajesh Shah]

On Mon, Jun 05, 2006 at 04:46:16AM -0400, Adam Belay wrote:
> This patch modifies pci_disable_device() to clear IO and MEM from the
> COMMAND PCI config register.  This is required before entering D3,  but
> also probably a good general practice for system suspend.
> 
I'd submitted a patch to do this about a month ago, see
http://marc.theaimsgroup.com/?l=linux-pci&m=114669552428309&w=2

That patch does the same thing, but in arch specific code (since
that's where memory and IO decode get enabled today). This patch
will cover the other arch's too, so I'm fine with this if this
is the right thing to do. My original patch is already in Greg's
tree and needs to be removed if this patch is accepted.

thanks,
Rajesh

Re: [PATCH 8/9] PCI PM: clear IO and MEM when disabling a device

[Benjamin Herrenschmidt]

On Mon, 2006-06-05 at 04:46 -0400, Adam Belay wrote:
> This patch modifies pci_disable_device() to clear IO and MEM from the
> COMMAND PCI config register.  This is required before entering D3,  but
> also probably a good general practice for system suspend.

And will break a great deal of platforms. Don't do it :) The problem is,
I think, mostly related to firmware issues.

Ben.

Re: [PATCH 8/9] PCI PM: clear IO and MEM when disabling a device

[Adam Belay]

On Tue, 2006-06-06 at 10:32 +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2006-06-05 at 04:46 -0400, Adam Belay wrote:
> > This patch modifies pci_disable_device() to clear IO and MEM from the
> > COMMAND PCI config register.  This is required before entering D3,  but
> > also probably a good general practice for system suspend.
> 
> And will break a great deal of platforms. Don't do it :) The problem is,
> I think, mostly related to firmware issues.
> 
> Ben.

If the device must be enabled before passing control to firmware, then
shouldn't its controlling driver never call pci_disable_device()?  I'd
like to have pci_disable_device() actually disable devices, as this is
needed for D3.

Thanks,
Adam