linux-kernel - Re: [PATCH v3 05/27] PCI: tegra: Save msi chip in pci_sys

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Date:	Thu, 23 Oct 2014 14:23:26 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Xinwei Hu <huxinwei@...wei.com>, Wuyun <wuyun.wu@...wei.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	<linux-arch@...r.kernel.org>, <arnab.basu@...escale.com>,
	<Bharat.Bhushan@...escale.com>, <x86@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
	<xen-devel@...ts.xenproject.org>, Joerg Roedel <joro@...tes.org>,
	<iommu@...ts.linux-foundation.org>, <linux-mips@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-s390@...r.kernel.org>,
	Sebastian Ott <sebott@...ux.vnet.ibm.com>,
	"Tony Luck" <tony.luck@...el.com>, <linux-ia64@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	<sparclinux@...r.kernel.org>, Chris Metcalf <cmetcalf@...era.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Lucas Stach <l.stach@...gutronix.de>,
	David Vrabel <david.vrabel@...rix.com>,
	"Sergei Shtylyov" <sergei.shtylyov@...entembedded.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Thierry Reding <thierry.reding@...il.com>,
	"Thomas Petazzoni" <thomas.petazzoni@...e-electrons.com>,
	Liviu Dudau <liviu@...au.co.uk>
Subject: Re: [PATCH v3 05/27] PCI: tegra: Save msi chip in pci_sys_data

On 2014/10/23 13:18, Bjorn Helgaas wrote:
> On Wed, Oct 15, 2014 at 11:06:53AM +0800, Yijing Wang wrote:
>> Save msi chip in pci_sys_data instead of assign
>> msi chip to every pci bus in .add_bus().
>>
>> Signed-off-by: Yijing Wang <wangyijing@...wei.com>
>> ---
>>  drivers/pci/host/pci-tegra.c |   13 +++----------
>>  1 files changed, 3 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
>> index 3d43874..5af0525 100644
>> --- a/drivers/pci/host/pci-tegra.c
>> +++ b/drivers/pci/host/pci-tegra.c
>> @@ -694,15 +694,6 @@ static int tegra_pcie_map_irq(const struct pci_dev *pdev, u8 slot, u8 pin)
>>  	return irq;
>>  }
>>  
>> -static void tegra_pcie_add_bus(struct pci_bus *bus)
>> -{
>> -	if (IS_ENABLED(CONFIG_PCI_MSI)) {
>> -		struct tegra_pcie *pcie = sys_to_pcie(bus->sysdata);
>> -
>> -		bus->msi = &pcie->msi.chip;
>> -	}
>> -}
>> -
>>  static struct pci_bus *tegra_pcie_scan_bus(int nr, struct pci_sys_data *sys)
>>  {
>>  	struct tegra_pcie *pcie = sys_to_pcie(sys);
>> @@ -1881,11 +1872,13 @@ static int tegra_pcie_enable(struct tegra_pcie *pcie)
>>  
>>  	memset(&hw, 0, sizeof(hw));
>>  
>> +#ifdef CONFIG_PCI_MSI
>> +	hw.msi_chip = &pcie->msi.chip;
>> +#endif
> 
> Why did you use "#ifdef CONFIG_PCI_MSI" instead of the
> "IS_ENABLED(CONFIG_PCI_MSI)" used previously?

Just personal habit. :)

> 
> It's true that CONFIG_PCI_MSI will never be a tristate symbol, so we don't
> really *need* the extra smarts of IS_ENABLED(), but I'm fairly sympathetic
> to James' argument [1] that we should just use IS_ENABLED() all the time
> because it's simpler overall.
> 
> If you want to change the #ifdef to IS_ENABLED(), that should be a separate
> patch from your msi_chip change, and we can debate the merits of that by
> itself.
> 
> [1] http://lkml.iu.edu//hypermail/linux/kernel/1204.3/00081.html

Hi Bjorn, thanks for your guidance. I will use IS_ENABLED() instead of #ifdef for simplification
in a separate patch.

> 
>>  	hw.nr_controllers = 1;
>>  	hw.private_data = (void **)&pcie;
>>  	hw.setup = tegra_pcie_setup;
>>  	hw.map_irq = tegra_pcie_map_irq;
>> -	hw.add_bus = tegra_pcie_add_bus;
>>  	hw.scan = tegra_pcie_scan_bus;
>>  	hw.ops = &tegra_pcie_ops;
>>  
>> -- 
>> 1.7.1
>>
>> --
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> 
> .
> 


-- 
Thanks!
Yijing

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