[PATCH v4 2/9] PCI: host: rcar: Add MSI support

[Lucas Stach]

Am Freitag, den 21.03.2014, 14:15 +0000 schrieb
Phil.Edworthy at renesas.com:
> Hi Lucas,
> 
> Thanks for the review.
> 
> On 21/03/2014 11:18, Lucas wrote:
> > Subject: Re: [PATCH v4 2/9] PCI: host: rcar: Add MSI support
> > 
> > Am Freitag, den 21.03.2014, 10:32 +0000 schrieb Phil Edworthy:
> > > Signed-off-by: Phil Edworthy <phil.edworthy at renesas.com>
> > > ---
> > >  drivers/pci/host/pcie-rcar.c | 232 
> ++++++++++++++++++++++++++++++++++++++++++-
> > >  drivers/pci/host/pcie-rcar.h |   5 +
> > >  2 files changed, 236 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/pci/host/pcie-rcar.c 
> b/drivers/pci/host/pcie-rcar.c
> > > index 16670e5..cbbcd77 100644
> > > --- a/drivers/pci/host/pcie-rcar.c
> > > +++ b/drivers/pci/host/pcie-rcar.c
> > [...]
> > > +
> > > +static irqreturn_t rcar_pcie_msi_irq(int irq, void *data)
> > > +{
> > > +   struct rcar_pcie *pcie = data;
> > > +   struct rcar_msi *msi = &pcie->msi;
> > > +   unsigned long reg;
> > > +
> > > +   reg = pci_read_reg(pcie, PCIEMSIFR);
> > > +
> > > +   while (reg) {
> > > +      unsigned int index = find_first_bit(&reg, 32);
> > > +      unsigned int irq;
> > > +
> > > +      /* clear the interrupt */
> > > +      pci_write_reg(pcie, 1 << index, PCIEMSIFR);
> > > +
> > > +      irq = irq_find_mapping(msi->domain, index);
> > > +      if (irq) {
> > > +         if (test_bit(index, msi->used))
> > > +            generic_handle_irq(irq);
> > > +         else
> > > +            dev_info(pcie->dev, "unhandled MSI\n");
> > > +      } else {
> > > +         /*
> > > +          * that's weird who triggered this?
> > > +          * just clear it
> > > +          */
> > > +         dev_info(pcie->dev, "unexpected MSI\n");
> > > +      }
> > > +
> > > +      /* see if there's any more pending in this vector */
> > > +      reg = pci_read_reg(pcie, PCIEMSIFR);
> > > +   }
> > > +
> > > +   return IRQ_HANDLED;
> > > +}
> > > +
> > From your DT binding it seems you have only one interrupt from the PCIe
> > core, shared between the MSI irqs and the PCI legacy interrupts.
> > This means this handler may get called without an MSI irq pending, so
> > this function really should have a path where it's returning IRQ_NONE.
> Ah, yes you are right... though actually there are two interrupts, one has 
> some MSI and INTx, the other has the rest of the MSIs.
> 
This isn't reflected in the DT binding. If you already know that there
may be more than a single interrupt for MSI, please push this into the
binding by using named interrupts. Even if your driver doesn't support
it yet, additional functionality can always be added later, but the DT
should be a stable ABI describing your hardware.

So if you already know your hardware has more than one interrupt, please
put it in the binding, to avoid churn later on.

Regards,
Lucas
-- 
Pengutronix e.K.                           | Lucas Stach                 |
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