Message-ID: <546CC436.4000902@linaro.org>
Date: Wed, 19 Nov 2014 17:24:22 +0100
From: Tomasz Nowicki <tomasz.nowicki@linaro.org>
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To: Arnd Bergmann <arnd@arndb.de>, linux-arm-kernel@lists.infradead.org
CC: catalin.marinas@arm.com, will.deacon@arm.com, bhelgaas@google.com,
        lorenzo.pieralisi@arm.com, wangyijing@huawei.com,
        hanjun.guo@linaro.org, Liviu.Dudau@arm.com, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, rjw@rjwysocki.net,
        linaro-acpi@lists.linaro.org, linux-pci@vger.kernel.org,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org
Subject: Re: [PATCH 6/6] pci, acpi: Share ACPI PCI config space accessors.
References: <1416413091-13452-1-git-send-email-tomasz.nowicki@linaro.org> <1416413091-13452-7-git-send-email-tomasz.nowicki@linaro.org> <2360791.Aj7tQ0nCJ3@wuerfel>
In-Reply-To: <2360791.Aj7tQ0nCJ3@wuerfel>
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Sender: linux-kernel-owner@vger.kernel.org

On 19.11.2014 17:19, Arnd Bergmann wrote:
> On Wednesday 19 November 2014 17:04:51 Tomasz Nowicki wrote:
>> +/*
>> + * raw_pci_read/write - ACPI PCI config space accessors.
>> + *
>> + * ACPI spec defines MMCFG as the way we can access PCI config space,
>> + * so let MMCFG be default (__weak).
>> + *
>> + * If platform needs more fancy stuff, should provides its own implementation.
>> + */
>> +int __weak raw_pci_read(unsigned int domain, unsigned int bus,
>> +                       unsigned int devfn, int reg, int len, u32 *val)
>> +{
>> +       return pci_mmcfg_read(domain, bus, devfn, reg, len, val);
>> +}
>> +
>> +int __weak raw_pci_write(unsigned int domain, unsigned int bus,
>> +                        unsigned int devfn, int reg, int len, u32 val)
>> +{
>> +       return pci_mmcfg_write(domain, bus, devfn, reg, len, val);
>> +}
>> +
>>
>
> I think it would be better to avoid __weak functions here, as they tend
> to be hard to follow when trying to understand the code.
>
> How about using a Kconfig symbol like this:
>
> #ifdef CONFIG_ARCH_RAW_PCI_READWRITE
> int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
>                   int reg, int len, u32 *val);
> int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
>                    int reg, int len, u32 val);
> #else
> static inline int raw_pci_read(unsigned int domain, unsigned int bus,
> 	                       unsigned int devfn, int reg, int len, u32 *val)
> {
> 	return pci_mmcfg_read(domain, bus, devfn, reg, len, val);
> }
>
> static inline int raw_pci_write(unsigned int domain, unsigned int bus,
>               		                unsigned int devfn, int reg, int len, u32 val)
> {
>         return pci_mmcfg_write(domain, bus, devfn, reg, len, val);
> }
> #endif
>
> Same thing for the weak symbols in patch 5.
>

It makes sense to me, thanks!

Tomasz

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