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Date:   Thu, 8 Aug 2019 13:51:50 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@sifive.com>
To:     Bjorn Helgaas <helgaas@kernel.org>
cc:     linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        Wesley Terpstra <wesley@sifive.com>
Subject: Re: [PATCH v2] pci: Kconfig: select PCI_MSI_IRQ_DOMAIN by default
 on RISC-V
In-Reply-To: <20190808195546.GA7302@google.com>
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References: <alpine.DEB.2.21.9999.1907251426450.32766@viisi.sifive.com> <20190808195546.GA7302@google.com>
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Hi Bjorn,

On Thu, 8 Aug 2019, Bjorn Helgaas wrote:

> On Thu, Jul 25, 2019 at 02:28:07PM -0700, Paul Walmsley wrote:
> > From: Wesley Terpstra <wesley@sifive.com>
> > 
> > This is part of adding support for RISC-V systems with PCIe host 
> > controllers that support message-signaled interrupts.
> > 
> > Signed-off-by: Wesley Terpstra <wesley@sifive.com>
> > [paul.walmsley@sifive.com: wrote patch description; split this
> >  patch from the arch/riscv patch]
> > Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
> > ---
> >  drivers/pci/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> > index 2ab92409210a..beb3408a0272 100644
> > --- a/drivers/pci/Kconfig
> > +++ b/drivers/pci/Kconfig
> > @@ -52,7 +52,7 @@ config PCI_MSI
> >  	   If you don't know what to do here, say Y.
> >  
> >  config PCI_MSI_IRQ_DOMAIN
> > -	def_bool ARC || ARM || ARM64 || X86
> > +	def_bool ARC || ARM || ARM64 || X86 || RISCV
> 
> The other arches listed here either supply their own include/asm/msi.h
> or generate it:
> 
>   $ ls arch/*/include/asm/msi.h
>   arch/x86/include/asm/msi.h
> 
>   $ grep msi.h arch/*/include/asm/Kbuild
>   arch/arc/include/asm/Kbuild:generic-y += msi.h
>   arch/arm64/include/asm/Kbuild:generic-y += msi.h
>   arch/arm/include/asm/Kbuild:generic-y += msi.h
>   arch/mips/include/asm/Kbuild:generic-y += msi.h
>   arch/powerpc/include/asm/Kbuild:generic-y += msi.h
>   arch/sparc/include/asm/Kbuild:generic-y += msi.h
> 
> For example, see
> 
>   f8430eae9f1b ("PCI/MSI: Enable PCI_MSI_IRQ_DOMAIN support for ARC")
>   be091d468a0a ("arm64: PCI/MSI: Use asm-generic/msi.h")
>   0ab089c2548c ("ARM: Add msi.h to Kbuild")
> 
> I didn't look into the details of msi.h generation, but I assume
> RISC-V needs to do something similar?  If so, I think that should be
> part of this patch to avoid issues.
> 
> If CONFIG_GENERIC_MSI_IRQ_DOMAIN is defined, include/linux/msi.h
> #includes <asm/msi.h> and I don't see where that would come from.

Commit 251a44888183 ("riscv: include generic support for MSI irqdomains") 
has been merged upstream for this purpose:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=251a44888183003b0380df184835a2c00bfa39d7

The original patch was split into a RISC-V component and a generic PCI 
component to reduce the risk of merge conflicts.

Does that work for you?


- Paul