linux-kernel - Re: [PATCH 2/2] PCI: generic: Add set_msi

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Date:	Fri, 14 Nov 2014 07:19:22 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>
CC:	Will Deacon <Will.Deacon@....com>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] PCI: generic: Add set_msi_parent callback

On 2014/11/13 23:22, Lorenzo Pieralisi wrote:
> On Tue, Nov 11, 2014 at 11:52:27AM +0000, Liviu Dudau wrote:
>> On Tue, Nov 11, 2014 at 11:24:24AM +0000, Will Deacon wrote:
>>> Hi Suravee,
>>>
>>> On Mon, Nov 10, 2014 at 07:24:40PM +0000, suravee.suthikulpanit@....com wrote:
>>>> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
>>>
>>> I don't think this makes much sense a host controller callback. Why can't
>>> bus->msi be set in generic code?
>>
>> Because of the current way in which a bus gets created and them immediately used for
>> scanning devices if you use pci_scan_root_bus(). Alternative is to use pci_create_root_bus()
>> and increase your code size with the body of pci_scan_root_bus().
>>
>> Solution is to have pci_host_bridge holding the msi_chip pointer and that gets created
>> before root bus, with pci_scan_root_bus() now having all the info needed to do successful
>> setup of scanned devices.
> 
> Why can't we add a hook like pci_bus_assign_domain_nr(), say:
> 
> pci_bus_msi_init()
> 
> in pci_create_root_bus() that does what Suravee wants in a generic way ?
+1
BTW, x86 may have multiple MSI controllers/domains under a host bridge,
so prefer calling it for every bus instead of for root bus only.
Regards!
Gerry
> 
> What am I missing ?
> 
> Lorenzo
> 
>>
>> Best regards,
>> Liviu
>>
>>>
>>>>  static struct pci_ops gen_pci_ops = {
>>>>  	.read	= gen_pci_config_read,
>>>>  	.write	= gen_pci_config_write,
>>>> +	.set_msi_parent = gen_pci_set_msi_parent,
>>>>  };
>>>>  
>>>>  static const struct of_device_id gen_pci_of_match[] = {
>>>> @@ -313,6 +324,9 @@ static int gen_pci_probe(struct platform_device *pdev)
>>>>  		return err;
>>>>  	}
>>>>  
>>>> +	pci->mchip = of_pci_find_msi_chip_by_node(of_parse_phandle(np,
>>>> +						  "msi-parent", 0));
>>>
>>> This bit should be in the generic of_pci.c code and not duplicated for
>>> each host controller.
>>>
>>> Will
>>>
>>
>> -- 
>> ====================
>> | I would like to |
>> | fix the world,  |
>> | but they're not |
>> | giving me the   |
>>  \ source code!  /
>>   ---------------
>>     ¯\_(ツ)_/¯
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