Subject: Re: [PATCHv4 1/2] ppc64: perform proper max_bus_speed detection

From: Lucas Kannebley Tavares <[email-masked]>
Date: Thu, 25 Apr 2013 14:34:32 -0300

On 04/24/2013 08:48 PM, Tony Breeds wrote:
> On Wed, Apr 24, 2013 at 07:54:49PM -0300, [email-masked] wrote:
>> From: Lucas Kannebley Tavares<[email-masked]>
>>
>> On pseries machines the detection for max_bus_speed should be done
>> through an OpenFirmware property. This patch adds a function to perform
>> this detection and a hook to perform dynamic adding of the function only for
>> pseries. This is done by overwriting the weak
>> pcibios_root_bridge_prepare function which is called by pci_create_root_bus().
>>
>> Signed-off-by: Lucas Kannebley Tavares<[email-masked]>
>> ---
>>   arch/powerpc/include/asm/machdep.h       |  2 ++
>>   arch/powerpc/kernel/pci-common.c         |  8 +++++
>>   arch/powerpc/platforms/pseries/pci.c     | 51 ++++++++++++++++++++++++++++++++
>>   arch/powerpc/platforms/pseries/pseries.h |  4 +++
>>   arch/powerpc/platforms/pseries/setup.c   |  2 ++
>>   5 files changed, 67 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
>> index 3d6b410..8f558bf 100644
>> --- a/arch/powerpc/include/asm/machdep.h
>> +++ b/arch/powerpc/include/asm/machdep.h
>> @@ -107,6 +107,8 @@ struct machdep_calls {
>>   	void		(*pcibios_fixup)(void);
>>   	int		(*pci_probe_mode)(struct pci_bus *);
>>   	void		(*pci_irq_fixup)(struct pci_dev *dev);
>> +	int		(*pcibios_root_bridge_prepare)(struct pci_host_bridge
>> +				*bridge);
>>
>>   	/* To setup PHBs when using automatic OF platform driver for PCI */
>>   	int		(*pci_setup_phb)(struct pci_controller *host);
>> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
>> index fa12ae4..80986cf 100644
>> --- a/arch/powerpc/kernel/pci-common.c
>> +++ b/arch/powerpc/kernel/pci-common.c
>> @@ -844,6 +844,14 @@ int pci_proc_domain(struct pci_bus *bus)
>>   	return 1;
>>   }
>>
>> +int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>> +{
>> +	if (ppc_md.pcibios_root_bridge_prepare)
>> +		return ppc_md.pcibios_root_bridge_prepare(bridge);
>> +
>> +	return 0;
>> +}
>> +
>>   /* This header fixup will do the resource fixup for all devices as they are
>>    * probed, but not for bridge ranges
>>    */
>> diff --git a/arch/powerpc/platforms/pseries/pci.c b/arch/powerpc/platforms/pseries/pci.c
>> index 0b580f4..7f9c956 100644
>> --- a/arch/powerpc/platforms/pseries/pci.c
>> +++ b/arch/powerpc/platforms/pseries/pci.c
>> @@ -108,3 +108,54 @@ static void fixup_winbond_82c105(struct pci_dev* dev)
>>   }
>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND, PCI_DEVICE_ID_WINBOND_82C105,
>>   			 fixup_winbond_82c105);
>> +
>> +int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
>> +{
>> +	struct device_node *dn, *pdn;
>> +	struct pci_bus *bus;
>> +	const uint32_t *pcie_link_speed_stats;
>> +
>> +	bus = bridge->bus;
>> +
>> +	dn = pcibios_get_phb_of_node(bus);
>> +	if (!dn)
>> +		return 0;
>> +
>> +	for (pdn = dn; pdn != NULL; pdn = pdn->parent) {
>> +		pcie_link_speed_stats = (const uint32_t *) of_get_property(dn,
>> +			"ibm,pcie-link-speed-stats", NULL);
>> +		if (pcie_link_speed_stats)
>> +			break;
>> +	}
>
> Please use the helpers in include/linux/of.h rather than open coding
> this.
>
> Yours Tony

Hi Tony,

This is what I can find as an equivalent code:

	for (pdn = dn; pdn != NULL; pdn = of_get_next_parent(pdn)) {
		pcie_link_speed_stats = (const uint32_t *)
			of_get_property(dn,
				"ibm,pcie-link-speed-stats", NULL);
		if (pcie_link_speed_stats)
			break;
	}

is this your suggestion, or was it another approach that will have the 
same result?

Thanks,

-- 
Lucas Kannebley Tavares
Software Engineer
IBM Linux Technology Center