Patchwork PCI: save/restore max Latency Value for device LTR

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Submitter Hao, Xudong
Date May 8, 2012, 9:09 a.m.
Message ID <403610A45A2B5242BD291EDAE8B37D300FDBDA97@SHSMSX102.ccr.corp.intel.com>
Download mbox | patch
Permalink /patch/157642/
State Rejected
Headers show

Comments

Hao, Xudong - May 8, 2012, 9:09 a.m.
> -----Original Message-----
> From: Bjorn Helgaas [mailto:bhelgaas@google.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.

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Bjorn Helgaas - May 19, 2012, 12:27 a.m.
On Tue, May 8, 2012 at 3:09 AM, Hao, Xudong <xudong.hao@intel.com> wrote:
>> -----Original Message-----
>> From: Bjorn Helgaas [mailto:bhelgaas@google.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 {

Did you test this?

I can't believe this works at all.  You're calling
"pci_find_saved_cap(dev, PCI_EXT_CAP_ID_LTR)", which searches the
pci_dev->saved_cap_space list, but you never add a PCI_EXT_CAP_ID_LTR
buffer to that list.

Bjorn
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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 {