Re: restore missing PCI registers after reset

Michael S. Tsirkin
2006-08-21T13:23:05Z

Quoting r. Greg KH <gregkh@suse.de>:
> Subject: Re: restore missing PCI registers after reset
>
> On Wed, Jul 26, 2006 at 07:32:26PM +0300, Michael S. Tsirkin wrote:
> > Quoting r. Greg KH <gregkh@suse.de>:
> > > I think pci_restore_state() already restores the msi and msix state,
> > > take a look at the latest kernel version :)
> >
> > Yes, I know :)
> > but I am not talking abotu MSI/MSI-X, I am talking about the following:
> > > > > PCI-X device: PCI-X command register
> > > > > PCI-X bridge: upstream and downstream split transaction registers
> > > > > PCI Express : PCI Express device control and link control registers
> >
> > these register values include maxumum MTU for PCI express and other vital
> > data.
>
> Make up a patch that shows how you would save these in a generic way and
> we can discuss it. I know people have talked about saving the extended
> PCI config space for devices that need it, so that might be all you
> need to do here.

Like this?

--

Restore PCI Express capability registers after PM event.
This includes maxumum MTU for PCI express and other vital data.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9f79dd6..198b200 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -443,6 +443,52 @@ pci_power_t pci_choose_state(struct pci_

EXPORT_SYMBOL(pci_choose_state);

+static int __pci_save_pcie_state(struct pci_dev *dev)
+{
+ int pos, i = 0;
+ struct pci_cap_saved_state *save_state;
+ u16 *cap;
+
+ pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ if (pos <= 0)
+ return 0;
+
+ save_state = kzalloc(sizeof(struct pci_cap_saved_state) + sizeof(u16) * 4,
+ GFP_KERNEL);
+ if (!save_state) {
+ printk(KERN_ERR "Out of memory in pci_save_pcie_state\n");
+ return -ENOMEM;
+ }
+ cap = (u16 *)&save_state->data[0];
+
+ pci_read_config_word(dev, pos + PCI_EXP_DEVCTL, &cap[i++]);
+ pci_read_config_word(dev, pos + PCI_EXP_LNKCTL, &cap[i++]);
+ pci_read_config_word(dev, pos + PCI_EXP_SLTCTL, &cap[i++]);
+ pci_read_config_word(dev, pos + PCI_EXP_RTCTL, &cap[i++]);
+ pci_add_saved_cap(dev, save_state);
+ return 0;
+}
+
+static void __pci_restore_pcie_state(struct pci_dev *dev)
+{
+ int i = 0, pos;
+ struct pci_cap_saved_state *save_state;
+ u16 *cap;
+
+ save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
+ pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ if (!save_state || pos <= 0)
+ return;
+ cap = (u16 *)&save_state->data[0];
+
+ pci_write_config_word(dev, pos + PCI_EXP_DEVCTL, cap[i++]);
+ pci_write_config_word(dev, pos + PCI_EXP_LNKCTL, cap[i++]);
+ pci_write_config_word(dev, pos + PCI_EXP_SLTCTL, cap[i++]);
+ pci_write_config_word(dev, pos + PCI_EXP_RTCTL, cap[i++]);
+ pci_remove_saved_cap(save_state);
+ kfree(save_state);
+}
+
/**
* pci_save_state - save the PCI configuration space of a device before suspending
* @dev: - PCI device that we're dealing with
@@ -458,6 +504,8 @@ pci_save_state(struct pci_dev *dev)
return i;
if ((i = pci_save_msix_state(dev)) != 0)
return i;
+ if ((i = __pci_save_pcie_state(dev)) != 0)
+ return i;
return 0;
}

@@ -471,6 +519,9 @@ pci_restore_state(struct pci_dev *dev)
int i;
int val;

+ /* PCI Express register must be restored first */
+ __pci_restore_pcie_state(dev);
+
/*
* The Base Address register should be programmed before the command
* register(s)

--
MST