Re: [Patch v5 4/6] PCI/ACPI: Consolidate common PCI host bridge code into ACPI core

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Jiang Liu <jiang.liu@linux.intel.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	"hanjun.guo@linaro.org" <hanjun.guo@linaro.org>,
	Liviu Dudau <Liviu.Dudau@arm.com>,
	Yijing Wang <wangyijing@huawei.com>, Len Brown <lenb@kernel.org>,
	Lv Zheng <lv.zheng@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"x86 @ kernel . org" <x86@kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [Patch v5 4/6] PCI/ACPI: Consolidate common PCI host bridge code into ACPI core
Date: Thu, 11 Jun 2015 17:18:08 +0100	[thread overview]
Message-ID: <20150611161808.GE23914@red-moon> (raw)
In-Reply-To: <55787191.6060400@linux.intel.com>

Hi Gerry,

On Wed, Jun 10, 2015 at 06:19:13PM +0100, Jiang Liu wrote:
> On 2015/6/11 0:48, Lorenzo Pieralisi wrote:
> > On Tue, Jun 09, 2015 at 05:58:15PM +0100, Jiang Liu wrote:
> >> On 2015/6/10 0:12, Lorenzo Pieralisi wrote:
> > 
> > [...]
> > 
> >>>> +struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
> >>>> +				     struct acpi_pci_root_ops *ops,
> >>>> +				     struct acpi_pci_root_info *info,
> >>>> +				     void *sysdata, int segment, int node)
> >>>
> >>> I do not think you need to pass segment and node, they clutter the
> >>> function signature when you can retrieve them from root, I would
> >>> make them local variables and use root->segment and acpi_get_node
> >>> in the function body to retrieve them.
> >> On x86, node and segment may be overridden under certain conditions.
> >> For example, segment will always be 0 if 'pci_ignore_seg' is set.
> > 
> > Ok, so the question would be then why do you not override the value
> > in root->segment then (actually, is it *correct* to leave the segment
> > value in root-> unchanged even if it is overriden) ?
> > 
> > Anyway, node is just used for a printk, why do not you add segment and
> > node to acpi_pci_root_info ? Just cosmetic stuff, trying to help you
> > simplify the code, it is not easy to parse.
> Hi Lorenzo,
> 	I used the complex prototype to explicitly reminder callers
> that you need to prepare all these information. If simpler interface
> is preferred, we could pack all ops, sysdata, segment, node, root
> into info, that there's will be only one parameter "info" left.
> The drawback is that it will add several lines of code to each arch
> using this interface. So prefer simpler interface or less lines of code?:)

I was just referring to segment and node parameters, I think that having
them in the parameters list is overkill and they can be encapsulated.

With the changes discussed previously feel free to add my:

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

> Thanks!
> Gerry
> 
> > 
> > Thanks,
> > Lorenzo
> > 
> 