linux-kernel - Re: [PATCH V5 02/15] acpi, pci, mcfg: Provide default RAW ACPI PCI config space accessors.

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Date:	Wed, 17 Feb 2016 12:39:33 +0000
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Tomasz Nowicki <tn@...ihalf.com>
Cc:	helgaas@...nel.org, arnd@...db.de, will.deacon@....com,
	catalin.marinas@....com, rafael@...nel.org, hanjun.guo@...aro.org,
	okaya@...eaurora.org, jiang.liu@...ux.intel.com,
	jchandra@...adcom.com, Stefano.Stabellini@...citrix.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jcm@...hat.com
Subject: Re: [PATCH V5 02/15] acpi, pci, mcfg: Provide default RAW ACPI PCI
 config space accessors.

On Tue, Feb 16, 2016 at 02:53:32PM +0100, Tomasz Nowicki wrote:
> Lets keep RAW ACPI PCI config space accessors empty by default,
> since we are note sure if they are necessary accross all archs.
> Once we sort this out, we can provide generic version or let
> architectures to overwrite, like now x86.

"ACPICA code requires raw PCI bus accessors in order to give AML
access to PCI_Config regions in platforms where they are actually
used. The raw PCI bus accessors implementation is arch-dependent,
therefore this patch adds a weak generic implementation (for now
empty but can be generalized if common functionality is found among
arches) allowing arches where PCI_Config regions are currently required
to override it (eg x86) as needed and providing at the same time
default stubs for arches that do not require them".

?

> Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> Tested-by: Jeremy Linton <jeremy.linton@....com>
> Tested-by: Duc Dang <dhdang@....com>
> Tested-by: Dongdong Liu <liudongdong3@...wei.com>
> Tested-by: Hanjun Guo <hanjun.guo@...aro.org>
> Tested-by: Graeme Gregory <graeme.gregory@...aro.org>
> Tested-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/acpi/pci_mcfg.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index ea84365..0467b00 100644
> --- a/drivers/acpi/pci_mcfg.c
> +++ b/drivers/acpi/pci_mcfg.c
> @@ -21,6 +21,26 @@
>  static DEFINE_MUTEX(pci_mmcfg_lock);
>  LIST_HEAD(pci_mmcfg_list);
>  
> +/*
> + * raw_pci_read/write - raw ACPI PCI config space accessors.
> + *
> + * By defauly (__weak) these accessors are empty and should be overwritten

s/defauly/default

> + * by architectures which support operations on ACPI PCI_Config regions,
> + * see osl.c file.

Add the path or remove the file reference.

> + */
> +
> +int __weak raw_pci_read(unsigned int domain, unsigned int bus,
> +			unsigned int devfn, int reg, int len, u32 *val)
> +{
> +	return PCIBIOS_DEVICE_NOT_FOUND;
> +}
> +
> +int __weak raw_pci_write(unsigned int domain, unsigned int bus,
> +			 unsigned int devfn, int reg, int len, u32 val)
> +{
> +	return PCIBIOS_DEVICE_NOT_FOUND;
> +}
> +
>  static void list_add_sorted(struct pci_mmcfg_region *new)
>  {
>  	struct pci_mmcfg_region *cfg;

Note: this patch is not strictly required, but it is nice because
it removes the raw/dumb/empty accessors from ARM64 code (where they do not
belong), so:

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>