Re: [PATCH] PCI/DPC: Fix INT legacy interrupt in dpc_irq

[poza]

On 2018-03-01 21:08, Bjorn Helgaas wrote:
> Hi Oza,
>
> On Wed, Jan 31, 2018 at 09:48:55PM +0530, Oza Pawandeep wrote:
> > Current dpc driver acknowledge the interrupt in deferred work, which 
> > works
> > okay since LPI are edge triggered.
> > But when RP does not have MSI support, port service driver falls back 
> > to
> > legacy GIC SPI interrupts, and with current code we do not acknowledge 
> > the
> > interrupt and we get dpc interrupt storm.
> > This patch acknowledges the interrupt in interrupt handler.
>
> Would you mind rephrasing this changelog in generic PCIe terms?  E.g.,
> "LPI" and "GIC SPI" are meaningless to me (I assume they're
> arm64-specific things), but I don't think it's any arm64-specific
> thing that motivates this change.  IIUC, the issue should occur any
> time we're not using MSI, so we should be able to describe it in
> purely PCIe terms.
>
> s/dpc/DPC/ in text.
>
> It looks like this changelog is intended to be multiple paragraphs; if
> so, please leave a blank line between them.  It's a little awkward to
> infer "this is a new paragraph" from the fact that "the previous line
> didn't look full" :)
>
> Please rebase to my "master" branch (v4.16-rc1).  There was some minor
> change that made this not apply cleanly.
>
> > Signed-off-by: Oza Pawandeep <poza@xxxxxxxxxxxxxx>
> >
> > diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
> > index 2d976a6..570b561 100644
> > --- a/drivers/pci/pcie/pcie-dpc.c
> > +++ b/drivers/pci/pcie/pcie-dpc.c
> > @@ -134,7 +134,7 @@ static void interrupt_event_handler(struct 
> > work_struct *work)
> >  	}
> >
> >  	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
> > -		PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
> > +			      PCI_EXP_DPC_STATUS_TRIGGER);
> >  }
> >
> >  static void dpc_rp_pio_print_tlp_header(struct device *dev,
> > @@ -277,6 +277,8 @@ static irqreturn_t dpc_irq(int irq, void *context)
> >
> >  		schedule_work(&dpc->work);
> >  	}
> > +	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
> > +			      PCI_EXP_DPC_STATUS_INTERRUPT);
> >  	return IRQ_HANDLED;
> >  }
> >
> > --
> > Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm 
> > Technologies, Inc.,
> > a Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a 
> > Linux Foundation Collaborative Project.

Hi Bjorn,

Can I make this path on top of DPC/AER patch series ?

Regards,
Oza.