linux-kernel - RE: [PATCH] PCI: save/restore max Latency Value for device LTR

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Date:	Tue, 8 May 2012 09:09:56 +0000
From:	"Hao, Xudong" <xudong.hao@...el.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Xudong Hao <xudong.hao@...ux.intel.com>
CC:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"Zhang, Xiantao" <xiantao.zhang@...el.com>
Subject: RE: [PATCH] PCI: save/restore max Latency Value for device LTR

> -----Original Message-----
> From: Bjorn Helgaas [mailto:bhelgaas@...gle.com]
> >  }
> >
> 
> This doesn't make any sense to me.  "pos" is the offset of the PCI
> Express Capability (identifier 10h).  LTR is a separate extended
> capability (identifier 18h), so you at least have to look up its
> offset.
> 
Sorry paste a wrong patch...

How about this patch, not a formal patch.

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 111569c..eced407 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -910,6 +910,45 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
 		pci_write_config_word(dev, pos + PCI_EXP_SLTCTL2, cap[i++]);
 }
 
+static int pci_save_ltr_value(struct pci_dev *dev)
+{
+	int i = 0, pos;
+	struct pci_cap_saved_state *save_state;
+	u16 *cap;
+
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!pos)
+		return -ENOTSUPP;
+
+	save_state = pci_find_saved_cap(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state) {
+		dev_err(&dev->dev, "buffer not found in %s\n", __func__);
+		return -ENOMEM;
+	}
+	cap = (u16 *)&save_state->cap.ltr_data[0];
+
+	pci_read_config_word(dev, pos + PCI_LTR_MAX_SNOOP_LAT, &cap[i++]);
+	pci_read_config_word(dev, pos + PCI_LTR_MAX_NOSNOOP_LAT, &cap[i++]);
+}
+
+static void pci_restore_ltr_value(struct pci_dev *dev)
+{
+	int i = 0, pos;
+	struct pci_cap_saved_state *save_state;
+	u16 *cap;
+
+	if (!pci_ltr_supported(dev))
+		return;
+
+	save_state = pci_find_saved_cap(dev, PCI_EXT_CAP_ID_LTR);
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state || !pos)
+		return;
+	cap = (u16 *)&save_state->cap.ltr_data[0];
+
+	pci_write_config_word(dev, pos + PCI_LTR_MAX_SNOOP_LAT, cap[i++]);
+	pci_write_config_word(dev, pos + PCI_LTR_MAX_NOSNOOP_LAT, cap[i++]);
+}
 
 static int pci_save_pcix_state(struct pci_dev *dev)
 {
@@ -964,6 +1003,10 @@ pci_save_state(struct pci_dev *dev)
 		return i;
 	if ((i = pci_save_pcix_state(dev)) != 0)
 		return i;
+
+	if (pci_ltr_supported(dev))
+		return pci_save_ltr_value(dev);
+
 	return 0;
 }
 
@@ -1032,6 +1075,7 @@ void pci_restore_state(struct pci_dev *dev)
 	pci_restore_pcix_state(dev);
 	pci_restore_msi_state(dev);
 	pci_restore_iov_state(dev);
+	pci_restore_ltr_value(dev);
 
 	dev->state_saved = false;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e444f5b..6343aeb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -220,6 +220,7 @@ struct pci_cap_saved_data {
 	char cap_nr;
 	unsigned int size;
 	u32 data[0];
+	u32 ltr_data[0];
 };
 
 struct pci_cap_saved_state {
--
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