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Date: Thu, 24 Nov 2016 12:10:44 +0100
From: Tomasz Nowicki <tn@...ihalf.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
rafael@...nel.org, hanjun.guo@...aro.org,
Lorenzo.Pieralisi@....com, 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 V9 11/11] ARM64/PCI: Support for ACPI based PCI host
controller
On 23.11.2016 19:22, Bjorn Helgaas wrote:
> On Wed, Nov 23, 2016 at 12:21:03PM +0100, Tomasz Nowicki wrote:
>> Hi Bjorn,
>>
>> On 23.11.2016 00:13, Bjorn Helgaas wrote:
>>> Hi Tomasz,
>>>
>>> On Fri, Jun 10, 2016 at 09:55:19PM +0200, Tomasz Nowicki wrote:
>>>> Implement pci_acpi_scan_root and other arch-specific call so that ARM64
>>>> can start using ACPI to setup and enumerate PCI buses.
>>>>
>>>> Prior to buses enumeration the pci_acpi_scan_root() implementation looks
>>>> for configuration space start address (obtained through ACPI _CBA method or
>>>> MCFG interface). If succeed, it uses ECAM library to create new mapping.
>>>> Then it attaches generic ECAM ops (pci_generic_ecam_ops) which are used
>>>> for accessing configuration space later on.
>>>> ...
>>>
>>>> +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;
>>>> +
>>>> + ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
>>>> + if (!ri)
>>>> + return NULL;
>>>> +
>>>> + ri->cfg = pci_acpi_setup_ecam_mapping(root);
>>>> + if (!ri->cfg) {
>>>> + kfree(ri);
>>>> + return NULL;
>>>> + }
>>>> +
>>>> + acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
>>>
>>> This has already been merged, but this isn't right, is it? We're
>>> writing a host controller-specific pointer into the single system-wide
>>> acpi_pci_root_ops, then passing it on to acpi_pci_root_create().
>>>
>>> Today, I think ri->cfg->ops->pci_ops is always &pci_generic_ecam_ops,
>> >from this path:
>>>
>>> ri->cfg = pci_acpi_setup_ecam_mapping
>>> cfg = pci_ecam_create(..., &pci_generic_ecam_ops)
>>> cfg = kzalloc(...)
>>> cfg->ops = ops # &pci_generic_ecam_ops
>>>
>>> But we're about to merge the ECAM quirks series, which will mean it
>>> may not be &pci_generic_ecam_ops. Even apart from the ECAM quirks, we
>>> should avoid this pattern of putting device-specific info in a single
>>> shared structure because it's too difficult to verify that it's
>>> correct.
>>>
>>
>> Well spotted. I agree, we need to fix this. How about this:
>> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
>> index fb439c7..31c0e1c 100644
>> --- a/arch/arm64/kernel/pci.c
>> +++ b/arch/arm64/kernel/pci.c
>> @@ -152,33 +152,35 @@ static void
>> pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
>>
>> ri = container_of(ci, struct acpi_pci_generic_root_info, common);
>> pci_ecam_free(ri->cfg);
>> + kfree(ci->ops);
>> 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)
>> {
>> int node = acpi_get_node(root->device->handle);
>> struct acpi_pci_generic_root_info *ri;
>> struct pci_bus *bus, *child;
>> + struct acpi_pci_root_ops *root_ops;
>>
>> ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
>> if (!ri)
>> return NULL;
>>
>> + root_ops = kzalloc_node(sizeof(*root_ops), GFP_KERNEL, node);
>> + if (!root_ops)
>> + return NULL;
>> +
>> ri->cfg = pci_acpi_setup_ecam_mapping(root);
>> if (!ri->cfg) {
>> kfree(ri);
>> + kfree(root_ops);
>> return NULL;
>> }
>>
>> - 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);
>> + root_ops->release_info = pci_acpi_generic_release_info;
>> + root_ops->pci_ops = &ri->cfg->ops->pci_ops;
>> + bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg);
>> if (!bus)
>> return NULL;
>>
>> Of course, this should be the part of ECAM quirks core patches.
>>
>> The other option we have is to remove "struct pci_ops *pci_ops;"
>> from acpi_pci_root_ops structure and pass struct pci_ops as an extra
>> argument to acpi_pci_root_create(). What do you think?
>
> I think your patch above is fine and avoids the need to change the x86 and
> ia64 code. Would you mind packaging this up with a changelog and
> signed-off-by? I can take care of putting it in the ECAM series.
>
Sure, I have just sent the patch in replay to ECAM quirks V6 patch set.
Let us know when you update your branch so we base our quirks on it.
Thanks,
Tomasz
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