linux-kernel - Re: [PATCH v3 12/26] PCI: keystone: Prevent ARM32 specific code to be compiled for ARM64

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Date:   Fri, 12 Apr 2019 12:11:56 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Murali Karicheri <m-karicheri2@...com>,
        Jingoo Han <jingoohan1@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-kernel@...s.com,
        Minghuan Lian <minghuan.Lian@....com>,
        Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
        Jesper Nilsson <jesper.nilsson@...s.com>
Subject: Re: [PATCH v3 12/26] PCI: keystone: Prevent ARM32 specific code to
 be compiled for ARM64

On Fri, Apr 12, 2019 at 02:20:06PM +0530, Kishon Vijay Abraham I wrote:
> Hi Lorenzo,
> 
> On 11/04/19 8:33 PM, Lorenzo Pieralisi wrote:
> > On Mon, Mar 25, 2019 at 03:09:33PM +0530, Kishon Vijay Abraham I wrote:
> >> hook_fault_code is an ARM32 specific API for hooking into data abort.
> >> Since pci-keystone.c will be used for AM65X platforms which is an
> >> ARM64 platform,
> > 
> > Hi Kishon,
> > 
> > How is the problem plugged by the fault hook fixed on ARM64 ?
> 
> At least in AM654 platform, I don't see a bus error when PCIe device
> is not connected but returns 0xffffffff. So there is no necessary for
> hook_fault_code in AM654 platform.

That can't have much to do with ARM32<->ARM64, it is rather a platform
integration issue AFAICS. Russell has a point, this has to be documented
I can do it for you but I need additional information.

Thanks,
Lorenzo

> Thanks
> Kishon
> 
> > 
> > Thanks,
> > Lorenzo
> > 
> >> allow hook_fault_code to be compiled only for ARM32.
> >>
> >> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> >> ---
> >>  drivers/pci/controller/dwc/pci-keystone.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> >> index dfe54553d832..93296d434f40 100644
> >> --- a/drivers/pci/controller/dwc/pci-keystone.c
> >> +++ b/drivers/pci/controller/dwc/pci-keystone.c
> >> @@ -710,6 +710,7 @@ static int ks_pcie_config_legacy_irq(struct keystone_pcie *ks_pcie)
> >>  	return ret;
> >>  }
> >>  
> >> +#ifdef CONFIG_ARM
> >>  /*
> >>   * When a PCI device does not exist during config cycles, keystone host gets a
> >>   * bus error instead of returning 0xffffffff. This handler always returns 0
> >> @@ -729,6 +730,7 @@ static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
> >>  
> >>  	return 0;
> >>  }
> >> +#endif
> >>  
> >>  static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
> >>  {
> >> @@ -778,12 +780,14 @@ static int __init ks_pcie_host_init(struct pcie_port *pp)
> >>  	if (ret < 0)
> >>  		return ret;
> >>  
> >> +#ifdef CONFIG_ARM
> >>  	/*
> >>  	 * PCIe access errors that result into OCP errors are caught by ARM as
> >>  	 * "External aborts"
> >>  	 */
> >>  	hook_fault_code(17, ks_pcie_fault, SIGBUS, 0,
> >>  			"Asynchronous external abort");
> >> +#endif
> >>  
> >>  	ks_pcie_start_link(pci);
> >>  	dw_pcie_wait_for_link(pci);
> >> -- 
> >> 2.17.1
> >>