linux-kernel - Re: [PATCH 10/10] PCI/MSI: Remove useless bus->msi assignment

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Date:	Wed, 12 Nov 2014 13:54:01 +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>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Thierry Reding" <thierry.reding@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Subject: Re: [PATCH 10/10] PCI/MSI: Remove useless bus->msi assignment

On 2014/11/12 12:24, Bjorn Helgaas wrote:
> On Mon, Oct 27, 2014 at 03:48:47PM +0800, Yijing Wang wrote:
>> Thierry introduced MSI chip(now renamed to MSI controller)
>> framework to associate MSI chip and PCI bus in arm.
>> Other platforms still use its own arch MSI functions to
>> support MSI capability. Thierry introduced the bus->msi
>> assignment to make child bus can inherit bus->msi from the parent.
>> But in fact, drivers which used MSI chip always associate
>> MSI chip and PCI bus by add .add_bus() in arm PCI host bridge
>> drivers. Now we have saved MSI chip in pci_sys_data.
>> We can remove this bus->msi assignment safely.
>>
>> Signed-off-by: Yijing Wang <wangyijing@...wei.com>
>> CC: Thierry Reding <thierry.reding@...il.com>
>> CC: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
>> ---
>>  drivers/pci/msi.c   |    5 -----
>>  drivers/pci/probe.c |    1 -
>>  2 files changed, 0 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index f085f7f..27b6a54 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -37,11 +37,6 @@ struct msi_controller * __weak pcibios_msi_controller(struct pci_bus *bus)
>>  
>>  struct msi_controller *pci_msi_controller(struct pci_bus *bus)
>>  {
>> -	struct msi_controller *ctrl = bus->msi;
>> -
>> -	if (ctrl)
>> -		return ctrl;
>> -
>>  	return pcibios_msi_controller(bus);
>>  }
>>  
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 5ed9930..4b18bf2 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -682,7 +682,6 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>>  
>>  	child->parent = parent;
>>  	child->ops = parent->ops;
>> -	child->msi = parent->msi;
> 
> Does this mean that struct pci_bus.msi is now unused?  If not, where is it
> still used?

Yes, now all arm platforms save msi_chip in pci_sys_data, no one uses it again,
actually, no platform/pcihost never use it, because all arm pci host drivers use
pcibios_add_bus() to associate it and pci bus before. Remove it is safety.

Thanks!
Yijing.

> 
>>  	child->sysdata = parent->sysdata;
>>  	child->bus_flags = parent->bus_flags;
>>  
>> -- 
>> 1.7.1
>>
> 
> .
> 


-- 
Thanks!
Yijing

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