On 13/04/16 16:36, Tomasz Nowicki wrote:
> On 13.04.2016 17:23, Marc Zyngier wrote:
>> On 04/04/16 09:52, Tomasz Nowicki wrote:
>>> IORT shows representation of IO topology for ARM based systems.
>>> It describes how various components are connected together on
>>> parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.
>>>
>>> Initial support allows to:
>>> - register ITS MSI chip along with ITS translation ID and domain token
>>> - deregister ITS MSI chip based on ITS translation ID
>>> - find registered domain token based on ITS translation ID
>>> - map MSI RID based on PCI device and requester ID
>>> - find domain token based on PCI device and requester ID
>>>
>>> To: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
>>> Signed-off-by: Tomasz Nowicki <tn@xxxxxxxxxxxx>
>>> ---
>>> drivers/acpi/Kconfig | 3 +
>>> drivers/acpi/Makefile | 1 +
>>> drivers/acpi/iort.c | 335 ++++++++++++++++++++++++++++++++++++++++++++++++
>>> drivers/irqchip/Kconfig | 1 +
>>> include/linux/iort.h | 31 +++++
>>> 5 files changed, 371 insertions(+)
>>> create mode 100644 drivers/acpi/iort.c
>>> create mode 100644 include/linux/iort.h
>>>
>>
>> [...]
>>
>>> +static acpi_status
>>> +iort_find_dev_callback(struct acpi_iort_node *node, void *context)
>>> +{
>>> + struct acpi_iort_root_complex *pci_rc;
>>> + struct device *dev = context;
>>> + struct pci_bus *bus;
>>> +
>>> + switch (node->type) {
>>> + case ACPI_IORT_NODE_PCI_ROOT_COMPLEX:
>>> + bus = to_pci_bus(dev);
>>> + pci_rc = (struct acpi_iort_root_complex *)node->node_data;
>>> +
>>> + /*
>>> + * It is assumed that PCI segment numbers maps one-to-one
>>> + * with root complexes. Each segment number can represent only
>>> + * one root complex.
>>> + */
>>> + if (pci_rc->pci_segment_number == pci_domain_nr(bus))
>>> + return AE_OK;
>>
>> What guarantees that this is ever valid? As far as I know, pci_domain_nr
>> is completely arbitrary, and depends both on the probe order and the
>> phase of the moon. If you want this to be reliable, you need to allocate
>> the domain number from pci_segment_number.
>>
>> I must be missing something. Care to shed some light on this?
>>
> Sure. Please see:
> http://infocenter.arm.com/help/topic/com.arm.doc.den0049a/DEN0049A_IO_Remapping_Table.pdf
> 3.1.1.5 PCI root complex node
> PCI Segment number -> The PCI segment number, as in MCFG and as
> returned by _SEG in the namespace.
>
> So IORT spec states that pci_segment_number corresponds to the segment
> number from MCFG table and _SEG method. Here is my patch which makes
> sure pci_domain_nr(bus) is set properly:
> https://lkml.org/lkml/2016/2/16/418
Lovely. So this series is actually dependent on the PCI one. I guess we
need to solve that one first, because IORT seems pretty pointless if we
don't have PCI support. What's the plan?
M.
--
Jazz is not dead. It just smells funny...
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