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

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Message-ID: <20190412114824.GA8319@red-moon>
Date:   Fri, 12 Apr 2019 12:48:24 +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 04:59:36PM +0530, Kishon Vijay Abraham I wrote:
> Hi Lorenzo,
> 
> On 12/04/19 4:41 PM, Lorenzo Pieralisi wrote:
> > 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.
> 
> Right now only ARM32 exports hook_fault_code which was used by K2G (ARM32
> platform) and since AM654 (ARM64 platform) uses the same driver, it'll result
> in compilation error. Also AM654 doesn't require hook_fault_code (or something
> similar) because it doesn't throw bus error on accessing PCIe address space
> when PCI device is not connected).
> 
> Are you looking for some other information?

No thanks it was to confirm my understanding, it is really not
an ARM<->ARM64 issue, I will try to phrase it in a way that
is more explicit.

Lorenzo

> 
> Thanks
> Kishon
> > 
> > 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
> >>>>