Re: [PATCH v4 4/6] of/pci: add of_pci_dma_configure() update dma configuration

[Murali Karicheri <m-karicheri2-l0cyMroinI0@public.gmane.org>]

On 01/23/2015 06:41 PM, Bjorn Helgaas wrote:
> On Fri, Jan 23, 2015 at 05:32:37PM -0500, Murali Karicheri wrote:
>> Add of_pci_dma_configure() to allow updating the dma configuration
>> of the pci device using the configuration from DT of the parent of
>> the root bridge device.
>>
>> Cc: Joerg Roedel<joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
>> Cc: Grant Likely<grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> Cc: Rob Herring<robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>> Cc: Bjorn Helgaas<bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>> Cc: Will Deacon<will.deacon-5wv7dgnIgG8@public.gmane.org>
>> Cc: Russell King<linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
>> Cc: Arnd Bergmann<arnd-r2nGTMty4D4@public.gmane.org>
>> Cc: Suravee Suthikulpanit<Suravee.Suthikulpanit-5C7GfCeVMHo@public.gmane.org>
>>
>> Signed-off-by: Murali Karicheri<m-karicheri2-l0cyMroinI0@public.gmane.org>
>> ---
>>   drivers/of/of_pci.c    |   39 +++++++++++++++++++++++++++++++++++++++
>>   include/linux/of_pci.h |   12 ++++++++++++
>>   2 files changed, 51 insertions(+)
>>
>> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
>> index 88471d3..34878c9 100644
>> --- a/drivers/of/of_pci.c
>> +++ b/drivers/of/of_pci.c
>> @@ -2,6 +2,7 @@
>>   #include<linux/export.h>
>>   #include<linux/of.h>
>>   #include<linux/of_address.h>
>> +#include<linux/of_device.h>
>>   #include<linux/of_pci.h>
>>   #include<linux/slab.h>
>>
>> @@ -229,6 +230,44 @@ parse_failed:
>>   	return err;
>>   }
>>   EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
>> +
>> +/**
>> + * of_get_pci_root_bridge_parent - get the OF node of the root bridge's parent
>> + * @dev: ptr to pci_dev struct of the pci device
>> + *
>> + * This function will traverse the bus up to the root bus starting with
>> + * the child and return the OF node ptr to root bridge device's parent device.
>> + */
>> +struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev)
>
> I'm not an OF person, but this interface seems like it might be too
> special-purpose.  Maybe it would be enough to add
> "of_get_pci_root_bridge()", and the caller could do this:
>
>      struct device *bridge = of_get_pci_root_bridge(dev);
>      struct device_node *parent_np = bridge->parent->of_node;
>
> Also, the name "of_get_..." suggests that it increments a refcount, as
> of_get_parent() does.  But you aren't doing anything with the refcount.
>
> But I guess an "of_get_pci_root_bridge()" isn't doing anything OF-related,
> so maybe we should just add a "pci_get_host_bridge(struct pci_dev *)"
> to PCI instead.

Bjorn,

Thanks for the comment.

I think adding pci_get_host_bridge() is a good idea. There is already 
similar function in host-bridge.c. I have added this function re-using 
existing function find_pci_root_bus(). See the incremental diff below 
after this change. Does this look good?

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 34878c9..77b15b5 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -232,26 +232,6 @@ parse_failed:
  EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);

  /**
- * of_get_pci_root_bridge_parent - get the OF node of the root bridge's 
parent
- * @dev: ptr to pci_dev struct of the pci device
- *
- * This function will traverse the bus up to the root bus starting with
- * the child and return the OF node ptr to root bridge device's parent 
device.
- */
-struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev)
-{
-       struct pci_bus *bus = dev->bus;
-       struct device *bridge;
-
-       while (!pci_is_root_bus(bus))
-               bus = bus->parent;
-       bridge = bus->bridge;
-
-       return bridge->parent->of_node;
-}
-EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
-
-/**
   * of_pci_dma_configure - Setup DMA configuration
   * @dev: ptr to pci_dev struct of the pci device
   *
@@ -261,10 +241,9 @@ EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
  void of_pci_dma_configure(struct pci_dev *pci_dev)
  {
         struct device *dev = &pci_dev->dev;
-       struct device_node *parent_np;
+       struct device *bridge = pci_get_host_bridge(pci_dev);

-       parent_np = of_get_pci_root_bridge_parent(pci_dev);
-       of_dma_configure(dev, parent_np);
+       of_dma_configure(dev, bridge->parent->of_node);
  }
  EXPORT_SYMBOL_GPL(of_pci_dma_configure);

diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
index 0e5f3c9..9803aa6 100644
--- a/drivers/pci/host-bridge.c
+++ b/drivers/pci/host-bridge.c
@@ -23,6 +23,13 @@ static struct pci_host_bridge 
*find_pci_host_bridge(struct pci_bus *bus)
         return to_pci_host_bridge(root_bus->bridge);
  }

+struct device *pci_get_host_bridge(struct pci_dev *dev)
+{
+       struct pci_bus *root_bus = find_pci_root_bus(dev->bus);
+
+       return root_bus->bridge;
+}
+
  void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
                                  void (*release_fn)(struct 
pci_host_bridge *),
                                  void *release_data)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 9603094..5bcdfa6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -513,6 +513,8 @@ static inline struct pci_dev 
*pci_upstream_bridge(struct pci_dev *dev)
         return dev->bus->self;
  }

+struct device *pci_get_host_bridge(struct pci_dev *dev);
+
  #ifdef CONFIG_PCI_MSI
  static inline bool pci_dev_msi_enabled(struct pci_dev *pci_dev)
  {
@@ -1823,6 +1825,7 @@ int pci_vpd_find_tag(const u8 *buf, unsigned int 
off, unsigned int len, u8 rdt);
  int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,
                               unsigned int len, const char *kw);

  /* PCI <-> OF binding helpers */
  #ifdef CONFIG_OF
  struct device_node;


>
> Bjorn
>
>> +{
>> +	struct pci_bus *bus = dev->bus;
>> +	struct device *bridge;
>> +
>> +	while (!pci_is_root_bus(bus))
>> +		bus = bus->parent;
>> +	bridge = bus->bridge;
>> +
>> +	return bridge->parent->of_node;
>> +}
>> +EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
>> +
>> +/**
>> + * of_pci_dma_configure - Setup DMA configuration
>> + * @dev: ptr to pci_dev struct of the pci device
>> + *
>> + * Function to update PCI devices's DMA configuration using the same
>> + * info from the OF node of root host bridge's parent.
>> + */
>> +void of_pci_dma_configure(struct pci_dev *pci_dev)
>> +{
>> +	struct device *dev =&pci_dev->dev;
>> +	struct device_node *parent_np;
>> +
>> +	parent_np = of_get_pci_root_bridge_parent(pci_dev);
>> +	of_dma_configure(dev, parent_np);
>> +}
>> +EXPORT_SYMBOL_GPL(of_pci_dma_configure);
>> +
>>   #endif /* CONFIG_OF_ADDRESS */
>>
>>   #ifdef CONFIG_PCI_MSI
>> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
>> index ce0e5ab..0465a2a 100644
>> --- a/include/linux/of_pci.h
>> +++ b/include/linux/of_pci.h
>> @@ -16,6 +16,8 @@ int of_pci_get_devfn(struct device_node *np);
>>   int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
>>   int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
>>   int of_get_pci_domain_nr(struct device_node *node);
>> +struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev);
>> +void of_pci_dma_configure(struct pci_dev *pci_dev);
>>   #else
>>   static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
>>   {
>> @@ -50,6 +52,16 @@ of_get_pci_domain_nr(struct device_node *node)
>>   {
>>   	return -1;
>>   }
>> +
>> +static inline struct device_node
>> +*of_get_pci_root_bridge_parent(struct pci_dev *dev)
>> +{
>> +	return NULL;
>> +}
>> +
>> +static inline void of_pci_dma_configure(struct pci_dev *pci_dev)
>> +{
>> +}
>>   #endif
>>
>>   #if defined(CONFIG_OF_ADDRESS)
>> --
>> 1.7.9.5
>>


-- 
Murali Karicheri
Linux Kernel, Texas Instruments