Re: enabling multiple MSI vectors for a DS port

[Kallol Biswas <ndprkm@gmail.com>]

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Hello Bjorn,
                We have worked around the issue by ack'ing dpc interrupt in
irq handler than in worker thread.

Regarding sharing the output of lspci -vv, we are not authorized to send
customer system's detail, otherwise we would be happy to do so.


Anyway, is there a good document on linux PCIe hotplug?



---------------------------------------------
static irqreturn_t dpc_irq(int irq, void *context)
{

struct dpc_dev *dpc = (struct dpc_dev *)context;

struct pci_dev *pdev = dpc->dev->port;

u16 status, source;


pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);

pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID,

&source);

if (!status)

return IRQ_NONE;


dev_info(&dpc->dev->device, "DPC containment event, status:%#06x
source:%#06x\n",

status, source);


if (status & PCI_EXP_DPC_STATUS_TRIGGER) {

          u16 reason = (status >> 1) & 0x3;

         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,

                   PCI_EXP_DPC_STATUS_INTERRUPT);



         dev_warn(&dpc->dev->device, "DPC %s triggered, remove downstream
devices\n",

         (reason == 0) ? "unmasked uncorrectable error" :

         (reason == 1) ? "ERR_NONFATAL" :

         (reason == 2) ? "ERR_FATAL" : "extended error");

          schedule_work(&dpc->work);

}

return IRQ_HANDLED;



On Tue, Feb 20, 2018 at 10:20 PM, Kallol Biswas <ndprkm@gmail.com> wrote:

> Hello Bjorn,
>                 We have worked around the issue by ack'ing dpc interrupt
> in irq handler than in worker thread.
>
> Regarding sharing the output of lspci -vv, we are not authorized to send
> customer system's detail, otherwise we would be happy to do so.
>
>
> Anyway, is there a good document on linux PCIe hotplug?
>
>
>
> ---------------------------------------------
> static irqreturn_t dpc_irq(int irq, void *context)
> {
>
> struct dpc_dev *dpc = (struct dpc_dev *)context;
>
> struct pci_dev *pdev = dpc->dev->port;
>
> u16 status, source;
>
>
> pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
>
> pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID,
>
> &source);
>
> if (!status)
>
> return IRQ_NONE;
>
>
> dev_info(&dpc->dev->device, "DPC containment event, status:%#06x
> source:%#06x\n",
>
> status, source);
>
>
> if (status & PCI_EXP_DPC_STATUS_TRIGGER) {
>
>           u16 reason = (status >> 1) & 0x3;
>
>          pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
>
>                    PCI_EXP_DPC_STATUS_INTERRUPT);
>
>
>
>          dev_warn(&dpc->dev->device, "DPC %s triggered, remove downstream
> devices\n",
>
>          (reason == 0) ? "unmasked uncorrectable error" :
>
>          (reason == 1) ? "ERR_NONFATAL" :
>
>          (reason == 2) ? "ERR_FATAL" : "extended error");
>
>           schedule_work(&dpc->work);
>
> }
>
> return IRQ_HANDLED;
>
> On Tue, Feb 13, 2018 at 10:44 AM, Bjorn Helgaas <helgaas@kernel.org>
> wrote:
>
>> Hi Kallol,
>>
>> On Tue, Feb 13, 2018 at 10:21:04AM -0800, Kallol Biswas wrote:
>> > Hi Bjorn,
>> >             I am facing an interrupt generation issue when single MSI
>> > is shared by both dpc and hotplug interrupt.
>> >
>> > The DS port is multi-MSI capable. What I have noticed that if I move
>> > the switch (with DS port) and OS disk to a different system multiple
>> > MSI vectors are allocated and dpc isr and hotplug isr are on different
>> > vectors.
>> >
>> > It seems that BIOS controls allocation of MSI vectors. Is there anyway
>> > to force linux kernel to allocate multiple vectors when port is
>> > capable?
>>
>> BIOS doesn't control the allocation of MSI vectors.  That's done by
>> Linux in pcie_init_service_irqs(), and it depends on many things: what
>> services are supported by Linux (hotplug, PME, AER, DPC), which ones
>> Linux is allowed to use (based on the ACPI _OSC method, so this part
>> can be influenced by the BIOS), etc.
>>
>> If you can share the "lspci -vv" and dmesg output for these two
>> systems, we can probably work out what's going on.
>>
>> Things should *work* even if DPC and hotplug need to share an
>> interrupt.  If that doesn't work, that's a Linux bug that should be
>> fixed.
>>
>> Bjorn
>>
>
>

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