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 16:59:36 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....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

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?

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
>>>>