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Message-ID: <20190628113555.GA21829@e121166-lin.cambridge.arm.com>
Date: Fri, 28 Jun 2019 12:35:55 +0100
From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To: "Z.q. Hou" <zhiqiang.hou@....com>
Cc: "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"l.subrahmanya@...iveil.co.in" <l.subrahmanya@...iveil.co.in>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
Leo Li <leoyang.li@....com>,
"catalin.marinas@....com" <catalin.marinas@....com>,
"will.deacon@....com" <will.deacon@....com>,
Mingkai Hu <mingkai.hu@....com>,
"M.h. Lian" <minghuan.lian@....com>,
Xiaowei Bao <xiaowei.bao@....com>
Subject: Re: [PATCHv5 04/20] PCI: mobiveil: Remove the flag
MSI_FLAG_MULTI_PCI_MSI
On Mon, Jun 17, 2019 at 10:34:35AM +0000, Z.q. Hou wrote:
[...]
> > There is nothing obvious. Write what you are fixing in the commit log and I will
> > apply the patch, I won't write the commit log for you. Anyone should be able
> > to understand why a patch was needed by reading the commit log, it is as
> > important as writing the code itself.
>
> With the flag MSI_FLAG_MULTI_PCI_MSI, when the Endpoint allocates
> multiple MSI, it will trigger the "WARN_ON(nr_irqs != 1);" in
> mobiveil_irq_msi_domain_alloc(), this is the issue this patch want to
> fix.
And that's wrong. Marc explained why this controller does not support
Multi MSI and that's what should go in the commit log, triggering
a WARN_ON is the least of the problems (and the WARN_ON can even
be removed after this patch is applied), if it was used as a bandaid
to prevent allocating Multi MSI it is even more broken.
Lorenzo
> Thanks,
> Zhiqiang
>
> >
> > Thanks,
> > Lorenzo
> >
> > > Thanks,
> > > Zhiqiang
> > >
> > > >
> > > > Lorenzo
> > > >
> > > > > Subbu, did you test with Endpoint supporting multi MSI?
> > > > >
> > > > > Thanks,
> > > > > Zhiqiang
> > > > >
> > > > > >
> > > > > > Thanks,
> > > > > > Lorenzo
> > > > > >
> > > > > > > Fixes: 1e913e58335f ("PCI: mobiveil: Add MSI support")
> > > > > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> > > > > > > Reviewed-by: Minghuan Lian <Minghuan.Lian@....com>
> > > > > > > ---
> > > > > > > V5:
> > > > > > > - Corrected the subject.
> > > > > > >
> > > > > > > drivers/pci/controller/pcie-mobiveil.c | 2 +-
> > > > > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > > >
> > > > > > > diff --git a/drivers/pci/controller/pcie-mobiveil.c
> > > > > > > b/drivers/pci/controller/pcie-mobiveil.c
> > > > > > > index 563210e731d3..a0dd337c6214 100644
> > > > > > > --- a/drivers/pci/controller/pcie-mobiveil.c
> > > > > > > +++ b/drivers/pci/controller/pcie-mobiveil.c
> > > > > > > @@ -703,7 +703,7 @@ static struct irq_chip
> > > > > > > mobiveil_msi_irq_chip = {
> > > > > > >
> > > > > > > static struct msi_domain_info mobiveil_msi_domain_info = {
> > > > > > > .flags = (MSI_FLAG_USE_DEF_DOM_OPS |
> > > > > > MSI_FLAG_USE_DEF_CHIP_OPS |
> > > > > > > - MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
> > > > > > > + MSI_FLAG_PCI_MSIX),
> > > > > > > .chip = &mobiveil_msi_irq_chip,
> > > > > > > };
> > > > > > >
> > > > > > > --
> > > > > > > 2.17.1
> > > > > > >
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