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[v3,05/10] PCI/PTM: Add pci_disable_ptm() wrapper

Message ID 20220906222351.64760-6-helgaas@kernel.org
State New
Headers show
Series PCI/PM: Always disable PTM for all devices during suspend | expand

Commit Message

Bjorn Helgaas Sept. 6, 2022, 10:23 p.m. UTC 
From: Bjorn Helgaas <bhelgaas@google.com>

Implement pci_disable_ptm() as a wrapper around an internal
__pci_disable_ptm() that we can use during suspend to disable PTM without
clearing dev->ptm_enabled.  A future commit will re-enable PTM during
resume when dev->ptm_enabled is set.

Export pci_disable_ptm(), which *does* clear dev->ptm_enabled, for use by
drivers that want to disable PTM.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pci.h      | 2 --
 drivers/pci/pcie/ptm.c | 9 ++++++++-
 include/linux/pci.h    | 2 ++
 3 files changed, 10 insertions(+), 3 deletions(-)

Comments

Mika Westerberg Sept. 7, 2022, 5:28 a.m. UTC | #1 
On Tue, Sep 06, 2022 at 05:23:46PM -0500, Bjorn Helgaas wrote:
> @@ -42,6 +42,13 @@ void pci_disable_ptm(struct pci_dev *dev)
>  	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
>  }

Since you export these, I suggest adding kernel-doc to explain how these
are supposed to be used in drivers (pre-conditions etc.).

> +void pci_disable_ptm(struct pci_dev *dev)
> +{
> +	__pci_disable_ptm(dev);
> +	dev->ptm_enabled = 0;
> +}
> +EXPORT_SYMBOL(pci_disable_ptm);

EXPORT_SYMBOL_GPL()?
Bjorn Helgaas Sept. 7, 2022, 9:12 p.m. UTC | #2 
On Wed, Sep 07, 2022 at 08:28:43AM +0300, Mika Westerberg wrote:
> On Tue, Sep 06, 2022 at 05:23:46PM -0500, Bjorn Helgaas wrote:
> > @@ -42,6 +42,13 @@ void pci_disable_ptm(struct pci_dev *dev)
> >  	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
> >  }
> 
> Since you export these, I suggest adding kernel-doc to explain how these
> are supposed to be used in drivers (pre-conditions etc.).

Currently there really aren't any preconditions, so kernel-doc would
repeat the function name and parameters without adding any real
information, but I think it would be good to add a few explanatory
comments.  It always seems obvious when writing it, but it's never so
obvious without all the context ;)

> > +void pci_disable_ptm(struct pci_dev *dev)
> > +{
> > +	__pci_disable_ptm(dev);
> > +	dev->ptm_enabled = 0;
> > +}
> > +EXPORT_SYMBOL(pci_disable_ptm);
> 
> EXPORT_SYMBOL_GPL()?

I don't feel strongly either way, but am inclined to do the same as
pci_enable_ptm() and pcie_ptm_enabled(), which are both EXPORT_SYMBOL.
We could change all of them at once if it's worthwhile.  Currently
there's only one caller (igc) in the tree.

Bjorn
diff mbox series

Patch

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 785f31086313..91a465460d0f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -507,11 +507,9 @@  static inline int pci_iov_bus_range(struct pci_bus *bus)
 #ifdef CONFIG_PCIE_PTM
 void pci_save_ptm_state(struct pci_dev *dev);
 void pci_restore_ptm_state(struct pci_dev *dev);
-void pci_disable_ptm(struct pci_dev *dev);
 #else
 static inline void pci_save_ptm_state(struct pci_dev *dev) { }
 static inline void pci_restore_ptm_state(struct pci_dev *dev) { }
-static inline void pci_disable_ptm(struct pci_dev *dev) { }
 #endif
 
 unsigned long pci_cardbus_resource_alignment(struct resource *);
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index ac51cd84793f..762299984469 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -29,7 +29,7 @@  static void pci_ptm_info(struct pci_dev *dev)
 		 dev->ptm_root ? " (root)" : "", clock_desc);
 }
 
-void pci_disable_ptm(struct pci_dev *dev)
+static void __pci_disable_ptm(struct pci_dev *dev)
 {
 	int ptm = dev->ptm_cap;
 	u16 ctrl;
@@ -42,6 +42,13 @@  void pci_disable_ptm(struct pci_dev *dev)
 	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
 }
 
+void pci_disable_ptm(struct pci_dev *dev)
+{
+	__pci_disable_ptm(dev);
+	dev->ptm_enabled = 0;
+}
+EXPORT_SYMBOL(pci_disable_ptm);
+
 void pci_save_ptm_state(struct pci_dev *dev)
 {
 	int ptm = dev->ptm_cap;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 54be939023a3..cb5f796e3319 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1678,10 +1678,12 @@  bool pci_ats_disabled(void);
 
 #ifdef CONFIG_PCIE_PTM
 int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
+void pci_disable_ptm(struct pci_dev *dev);
 bool pcie_ptm_enabled(struct pci_dev *dev);
 #else
 static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 { return -EINVAL; }
+static inline void pci_disable_ptm(struct pci_dev *dev) { }
 static inline bool pcie_ptm_enabled(struct pci_dev *dev)
 { return false; }
 #endif