[PATCH v3 1/2] PCI: add helper function to find root port for device

[PATCH v3 1/2] PCI: add helper function to find root port for device

[Lucas Stach]

This adds a simple way to get the root port a given device
is connected to.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
v2: new patch in v2
v3: rename to pci_find_rootport to fit better with other API
---
 drivers/pci/search.c | 20 ++++++++++++++++++++
 include/linux/pci.h  |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index a20ce7d5e2a7..7254f126096d 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -384,3 +384,23 @@ int pci_dev_present(const struct pci_device_id *ids)
 	return 0;
 }
 EXPORT_SYMBOL(pci_dev_present);
+
+/**
+ * pci_find_root_port - Returns the root port the given device is connected to.
+ * @dev: PCI device for which the root port should be found.
+ */
+struct pci_dev *pci_find_root_port(struct pci_dev *dev)
+{
+	struct pci_bus *bus = dev->bus;
+
+	/* If there is no bridge on the bus the passed device is a root port. */
+	if (!bus->self)
+		return dev;
+
+	/* Walk up the PCI hierarchy to the first level below the root. */
+	while (bus->parent && bus->parent->self)
+		bus = bus->parent;
+
+	return bus->self;
+}
+EXPORT_SYMBOL(pci_find_root_port);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 360a966a97a5..f4321c5ba653 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -844,6 +844,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
 }
 struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from);
 int pci_dev_present(const struct pci_device_id *ids);
+struct pci_dev *pci_find_root_port(struct pci_dev *dev);
 
 int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn,
 			     int where, u8 *val);
-- 
2.1.4

[PATCH v3 2/2] PCI: tegra: apply relaxed ordering fixup only on Tegra

[Lucas Stach]

The fixup to enable relaxed ordering on all PCI devices was
executed unconditionally if the Tegra PCI host driver was
built into the kernel. This doesn't play nice with a
multiplatform kernel executed on other platforms which
may not need this fixup.

Make sure to only apply the fixup if the root port is
a Tegra.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Thierry Reding <treding@nvidia.com>
---
v2:
- split out PCI hierarchy walk
- separate code from data by moving PCI IDs into own structure
v3:
- fixup for helper rename
- applied Thierry's ACK
---
 drivers/pci/host/pci-tegra.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index 6f9c29fa70e7..e87d79559723 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -635,10 +635,42 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0bf1, tegra_pcie_fixup_class);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0e1c, tegra_pcie_fixup_class);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0e1d, tegra_pcie_fixup_class);
 
+static const struct pci_device_id tegra_rootport_ids[] = {
+	{
+		/* Tegra20 4 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0bf0,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* Tegra20 2 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0bf1,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* Tegra30 4 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e1c,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* Tegra30 2 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e1d,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* Tegra124 4 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e12,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* Tegra124 1 lane root port */
+		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e13,
+		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
+	}, {
+		/* sentinel */
+	}
+};
+
 /* Tegra PCIE requires relaxed ordering */
 static void tegra_pcie_relax_enable(struct pci_dev *dev)
 {
-	pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_RELAX_EN);
+	if (pci_match_id(tegra_rootport_ids, pci_find_root_port(dev)))
+		pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
+					 PCI_EXP_DEVCTL_RELAX_EN);
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_ANY_ID, PCI_ANY_ID, tegra_pcie_relax_enable);
 
-- 
2.1.4

Re: [PATCH v3 1/2] PCI: add helper function to find root port for device

[Bjorn Helgaas]

On Tue, Jan 13, 2015 at 08:57:27PM +0100, Lucas Stach wrote:
> This adds a simple way to get the root port a given device
> is connected to.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
> v2: new patch in v2
> v3: rename to pci_find_rootport to fit better with other API
> ---
>  drivers/pci/search.c | 20 ++++++++++++++++++++
>  include/linux/pci.h  |  1 +
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index a20ce7d5e2a7..7254f126096d 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -384,3 +384,23 @@ int pci_dev_present(const struct pci_device_id *ids)
>  	return 0;
>  }
>  EXPORT_SYMBOL(pci_dev_present);
> +
> +/**
> + * pci_find_root_port - Returns the root port the given device is connected to.
> + * @dev: PCI device for which the root port should be found.
> + */
> +struct pci_dev *pci_find_root_port(struct pci_dev *dev)

This seems a little too generic.  There are still PCI (non-PCIe) systems,
and on those this will return some non-Root Port device, the meaning of
which is unclear.  I'm happy to put something like this in pci-tegra.c, but
until there are other potential users and we sort out the PCI/PCIe-ness of
the interface, I don't really want to make it global and exported.

> +{
> +	struct pci_bus *bus = dev->bus;
> +
> +	/* If there is no bridge on the bus the passed device is a root port. */

This assumption is false -- see the comment at pci_is_root_bus().

> +	if (!bus->self)
> +		return dev;
> +
> +	/* Walk up the PCI hierarchy to the first level below the root. */
> +	while (bus->parent && bus->parent->self)
> +		bus = bus->parent;
> +
> +	return bus->self;
> +}
> +EXPORT_SYMBOL(pci_find_root_port);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 360a966a97a5..f4321c5ba653 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -844,6 +844,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
>  }
>  struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from);
>  int pci_dev_present(const struct pci_device_id *ids);
> +struct pci_dev *pci_find_root_port(struct pci_dev *dev);
>  
>  int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn,
>  			     int where, u8 *val);
> -- 
> 2.1.4
> 

Re: [PATCH v3 2/2] PCI: tegra: apply relaxed ordering fixup only on Tegra

[Bjorn Helgaas]

On Tue, Jan 13, 2015 at 08:57:28PM +0100, Lucas Stach wrote:
> The fixup to enable relaxed ordering on all PCI devices was
> executed unconditionally if the Tegra PCI host driver was
> built into the kernel. This doesn't play nice with a
> multiplatform kernel executed on other platforms which
> may not need this fixup.
> 
> Make sure to only apply the fixup if the root port is
> a Tegra.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> Acked-by: Thierry Reding <treding@nvidia.com>
> ---
> v2:
> - split out PCI hierarchy walk
> - separate code from data by moving PCI IDs into own structure
> v3:
> - fixup for helper rename
> - applied Thierry's ACK
> ---
>  drivers/pci/host/pci-tegra.c | 34 +++++++++++++++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
> index 6f9c29fa70e7..e87d79559723 100644
> --- a/drivers/pci/host/pci-tegra.c
> +++ b/drivers/pci/host/pci-tegra.c
> @@ -635,10 +635,42 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0bf1, tegra_pcie_fixup_class);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0e1c, tegra_pcie_fixup_class);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0e1d, tegra_pcie_fixup_class);
>  
> +static const struct pci_device_id tegra_rootport_ids[] = {
> +	{
> +		/* Tegra20 4 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0bf0,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* Tegra20 2 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0bf1,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* Tegra30 4 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e1c,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* Tegra30 2 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e1d,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* Tegra124 4 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e12,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* Tegra124 1 lane root port */
> +		.vendor = PCI_VENDOR_ID_NVIDIA, .device = 0x0e13,
> +		.subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID
> +	}, {
> +		/* sentinel */
> +	}

The table is OK and I'll apply it after we resolve the pci_find_root_port()
thing, but it's unfortunate that we're signing up to the ongoing
maintenance a table like this requires.  I'm sure you've already tried
other possibilities and resigned yourself to this one, though.

> +};
> +
>  /* Tegra PCIE requires relaxed ordering */
>  static void tegra_pcie_relax_enable(struct pci_dev *dev)
>  {
> -	pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_RELAX_EN);
> +	if (pci_match_id(tegra_rootport_ids, pci_find_root_port(dev)))
> +		pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
> +					 PCI_EXP_DEVCTL_RELAX_EN);
>  }
>  DECLARE_PCI_FIXUP_FINAL(PCI_ANY_ID, PCI_ANY_ID, tegra_pcie_relax_enable);
>  
> -- 
> 2.1.4
> 

Re: [PATCH v3 1/2] PCI: add helper function to find root port for device

[Lucas Stach]

Am Freitag, den 23.01.2015, 16:34 -0600 schrieb Bjorn Helgaas:
> On Tue, Jan 13, 2015 at 08:57:27PM +0100, Lucas Stach wrote:
> > This adds a simple way to get the root port a given device
> > is connected to.
> > 
> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > ---
> > v2: new patch in v2
> > v3: rename to pci_find_rootport to fit better with other API
> > ---
> >  drivers/pci/search.c | 20 ++++++++++++++++++++
> >  include/linux/pci.h  |  1 +
> >  2 files changed, 21 insertions(+)
> > 
> > diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> > index a20ce7d5e2a7..7254f126096d 100644
> > --- a/drivers/pci/search.c
> > +++ b/drivers/pci/search.c
> > @@ -384,3 +384,23 @@ int pci_dev_present(const struct pci_device_id *ids)
> >  	return 0;
> >  }
> >  EXPORT_SYMBOL(pci_dev_present);
> > +
> > +/**
> > + * pci_find_root_port - Returns the root port the given device is connected to.
> > + * @dev: PCI device for which the root port should be found.
> > + */
> > +struct pci_dev *pci_find_root_port(struct pci_dev *dev)
> 
> This seems a little too generic.  There are still PCI (non-PCIe) systems,
> and on those this will return some non-Root Port device, the meaning of
> which is unclear.  I'm happy to put something like this in pci-tegra.c, but
> until there are other potential users and we sort out the PCI/PCIe-ness of
> the interface, I don't really want to make it global and exported.
> 
I moved it out of the Tegra PCIe driver on your request. Also I can
already see this being useful for the Keystone PCI host driver to
shorten the MTRS quirk function.

I will rename this to pcie_find_root_port() so it is clear that this is
PCIe specific, but keep it in the current location.

> > +{
> > +	struct pci_bus *bus = dev->bus;
> > +
> > +	/* If there is no bridge on the bus the passed device is a root port. */
> 
> This assumption is false -- see the comment at pci_is_root_bus().
> 
Right, will change this.

Regards,
Lucas

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