linux-kernel - Re: [PATCH V8 9/9] pci, acpi: ARM64 support for ACPI based generic PCI host controller

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Date:	Thu, 2 Jun 2016 11:44:59 +0200
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	helgaas@...nel.org, arnd@...db.de, will.deacon@....com,
	catalin.marinas@....com, rafael@...nel.org, hanjun.guo@...aro.org,
	okaya@...eaurora.org, jchandra@...adcom.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jcm@...hat.com, andrea.gallo@...aro.org, dhdang@....com,
	jeremy.linton@....com, liudongdong3@...wei.com, cov@...eaurora.org
Subject: Re: [PATCH V8 9/9] pci, acpi: ARM64 support for ACPI based generic
 PCI host controller

On 02.06.2016 11:35, Lorenzo Pieralisi wrote:
> On Mon, May 30, 2016 at 05:14:22PM +0200, Tomasz Nowicki wrote:
>> This patch implements pci_acpi_scan_root call so that ARM64 can start
>> using ACPI to setup and enumerate PCI buses.
>>
>> The implementation of pci_acpi_scan_root() looks up config space regions
>> through MCFG interface. Then ECAM library is doing a new mapping
>> and attach generic ECAM ops which are used for accessing config space.
>>
>> On ARM64, ACPI and DT can be enabled together, and in that case
>> we need to use generic domains. In order to do that we implement
>> ARM64 specific way of retrieving domain number from pci_config_window
>> structure.
>>
>> Since we enable PCI for ACPI we need to implement raw_pci_{read|write}
>> at the same time. ARM64 provides RAW accessors as long as there is
>> correlated valid pci_bus structure, but not before.
>>
>> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
>> Signed-off-by: Jayachandran C <jchandra@...adcom.com>
>
> [...]
>
>> +/* release_info: free resrouces allocated by init_info */
>
> Nit: s/resrouces/resources
>
>> +static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
>> +{
>> +	struct acpi_pci_generic_root_info *ri;
>> +
>> +	ri = container_of(ci, struct acpi_pci_generic_root_info, common);
>> +	pci_ecam_free(ri->cfg);
>> +	kfree(ri);
>> +}
>> +
>> +static struct acpi_pci_root_ops acpi_pci_root_ops = {
>> +	.release_info = pci_acpi_generic_release_info,
>> +};
>> +
>> +/* Interface called from ACPI code to setup PCI host controller */
>>   struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>>   {
>> -	/* TODO: Should be revisited when implementing PCI on ACPI */
>> -	return NULL;
>> +	int node = acpi_get_node(root->device->handle);
>> +	struct acpi_pci_generic_root_info *ri;
>> +	struct pci_bus *bus, *child;
>> +	int err;
>> +
>> +	ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
>> +	if (!ri)
>> +		return NULL;
>> +
>> +	err = pci_acpi_setup_ecam_mapping(root, ri);
>> +	if (err)
>> +		return NULL;
>                  ^
> Leaking memory -> kfree(ri)

I missed that. Will fix.

>
>> +	acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
>> +	bus = acpi_pci_root_create(root, &acpi_pci_root_ops, &ri->common,
>> +				   ri->cfg);
>> +	if (!bus)
>> +		return NULL;
>
> Ditto.

Here kfree(ri) is not needed. __acpi_pci_root_release_info will free ri 
inside of acpi_pci_root_create.

>
>> +
>> +	pci_bus_size_bridges(bus);
>> +	pci_bus_assign_resources(bus);
>> +
>> +	list_for_each_entry(child, &bus->children, node)
>> +		pcie_bus_configure_settings(child);
>> +
>> +	return bus;
>>   }
>>
>>   void pcibios_add_bus(struct pci_bus *bus)
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 9661c85..f66d188 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1390,7 +1390,12 @@ static inline int pci_domain_nr(struct pci_bus *bus)
>>   {
>>   	return bus->domain_nr;
>>   }
>> +/* Arch specific ACPI hook to set-up domain number */
>> +#ifdef CONFIG_ACPI
>> +int acpi_pci_bus_domain_nr(struct pci_bus *bus);
>
> Technically speaking, this should be introduced in a separate patch;
> given that I know it is a temporary plaster and no other architecture will
> have to implement it I reckon it is fine to leave it here, I will make
> it disappear as fast as I can.
>
> We can argue if it is best to move the ACPI bits into a separate file
> (acpi-pci.c), I am fine with keeping DT/ACPI in one file if that's fine
> with Catalin and Will.
>
> You can send the fix-ups above in the final pull request which I hope
> is nigh.
>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>

Thanks,
Tomasz