From mboxrd@z Thu Jan  1 00:00:00 1970
From: hanjun.guo@linaro.org (Hanjun Guo)
Date: Tue, 20 Jan 2015 10:39:16 +0800
Subject: [PATCH v7 06/17] ARM64 / ACPI: Make PCI optional for ACPI on ARM64
In-Reply-To: <20150119104240.GE11835@e104818-lin.cambridge.arm.com>
References: <1421247905-3749-1-git-send-email-hanjun.guo@linaro.org>
 <1421247905-3749-7-git-send-email-hanjun.guo@linaro.org>
 <20150116094913.GA13634@e104818-lin.cambridge.arm.com>
 <54BB51F1.8000900@linaro.org>
 <20150119104240.GE11835@e104818-lin.cambridge.arm.com>
Message-ID: <54BDBFD4.7050207@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 2015?01?19? 18:42, Catalin Marinas wrote:
> On Sun, Jan 18, 2015 at 06:25:53AM +0000, Hanjun Guo wrote:
>> On 2015?01?16? 17:49, Catalin Marinas wrote:
>>> On Wed, Jan 14, 2015 at 03:04:54PM +0000, Hanjun Guo wrote:
>>>> --- a/arch/arm64/kernel/pci.c
>>>> +++ b/arch/arm64/kernel/pci.c
>>>> @@ -10,6 +10,7 @@
>>>>     *
>>>>     */
>>>>
>>>> +#include <linux/acpi.h>
>>>>    #include <linux/init.h>
>>>>    #include <linux/io.h>
>>>>    #include <linux/kernel.h>
>>>> @@ -68,3 +69,30 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
>>>>    	bus->domain_nr = domain;
>>>>    }
>>>>    #endif
>>>> +
>>>> +/*
>>>> + * raw_pci_read/write - Platform-specific PCI config space access.
>>>> + *
>>>> + * Default empty implementation.  Replace with an architecture-specific setup
>>>> + * routine, if necessary.
>>>> + */
>>>> +int raw_pci_read(unsigned int domain, unsigned int bus,
>>>> +		  unsigned int devfn, int reg, int len, u32 *val)
>>>> +{
>>>> +	return -EINVAL;
>>>> +}
>>>> +
>>>> +int raw_pci_write(unsigned int domain, unsigned int bus,
>>>> +		unsigned int devfn, int reg, int len, u32 val)
>>>> +{
>>>> +	return -EINVAL;
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_ACPI
>>>> +/* Root bridge scanning */
>>>> +struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>>>> +{
>>>> +	/* TODO: Should be revisited when implementing PCI on ACPI */
>>>> +	return NULL;
>>>> +}
>>>> +#endif
> [...]
>>> When PCI is enabled and the above functions are compiled in, do they
>>> need to return any useful data or just -EINVAL. Are they ever called?
>>
>> They will be called if PCI root bridge is defined in DSDT, should I
>> print some warning message before it is implemented?
>
> My point: do they need to return real data when a PCI root bridge is
> defined in DSDT or you always expect them to always return some -E*? Can
> you explain why?

Not always return -E* or NULL;

For raw_pci_read/write(), they are needed to access the PCI config space
before the PCI root bus is created. so they will return 0 if access to
PCI config space is ok; pci_acpi_scan_root() will return root bus
pointer if it is successfully created.

Thanks
Hanjun