Re: [PATCH v3 3/4] of/pci: add of_pci_dma_configure() update dma configuration

[Murali Karicheri <m-karicheri2@ti.com>]

On 01/08/2015 11:06 AM, Will Deacon wrote:
> On Wed, Jan 07, 2015 at 06:49:53PM +0000, 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.
>>
>> Signed-off-by: Murali Karicheri<m-karicheri2@ti.com>
>> ---
>>   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)
>> +{
>> +	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);
>
> Whilst I think this is the right overall structure, I think this function
> should determine the set of DMA aliases for the device and pass that through
> to the IOMMU (as mentioned in my reply to the cover letter). Then we just
> need to work out what we're doing for groups.
>
> Will
Will,

Could you add this as as a follow up patch as I don't have a platformm 
that support IOMMU and as such my understanding of the IOMMU is limited?

I can help test the change to make sure it has no side effect on 
Keystone that doesn't support IOMMU.

Thanks.
-- 
Murali Karicheri
Linux Kernel, Texas Instruments