linux-kernel - Re: [PATCH] powerpc/pci: Improve device hotplug initialization

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Date:	Mon, 3 Jun 2013 10:28:47 +0800
From:	Chen Yuanquan-B41889 <B41889@...escale.com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	Yuanquan Chen <Yuanquan.Chen@...escale.com>,
	Hiroo Matsumoto <matsumoto.hiroo@...fujitsu.com>
Subject: Re: [PATCH] powerpc/pci: Improve device hotplug initialization

On 06/01/2013 09:58 PM, Guenter Roeck wrote:
> On Fri, May 31, 2013 at 03:44:07PM +1000, Benjamin Herrenschmidt wrote:
>> On Thu, 2013-05-30 at 22:14 -0700, Guenter Roeck wrote:
>>> On Wed, May 29, 2013 at 05:30:41PM +0800, Chen Yuanquan-B41889 wrote:
>>>> On 05/29/2013 01:35 AM, Guenter Roeck wrote:
>>>>> bios_add_device(). Drop explicit calls to pcibios_setup_device();
>>>>> this makes pcibios_setup_bus_devices() a noop function which could
>>>>> eve
>>>> Yeah, it's more reasonable to do the irq and DMA related initialization
>>>> in one code path for all devices.
>>>>
>>> Any comments / feedback on the code itself ?
>> Sorry, I haven't had a chance to review it yet, I'm fairly bogged down
>> at the moment. I want to tread carefully because the previous iteration
>> of changing that stuff did break a few platforms in the end.
>>
> Hi Ben,
>
> the comment was actuially directed towards Yuanquan.
>
> No problem, take your time. I did my best to test it, but I agree that this is a
> critical area of the code, and it would be desirable to get additional scrutiny
> and test feedback.
>
> The code has been running in our system (P2020 and P5040) for several months.
> I was preparing a patch for upstream submission when I noticed commit 37f02195b.
> After testing ithis commit, I noticed the problems with it and wrote this patch,
> which aligns the code with our initial patch. I tested it as good as I could on
> our systems as well as with a P5040 evaluation board and an Intel GE PCIe
> card.
>
> Thanks,
> Guenter
>

Hi Guenter,

Your patch makes sure the initialization of DMA and irq in one code path 
and also
avoids the initialization called two times(in pci bus scanning and 
pci_enable_device()
in device driver) for no-hot-plugged pci device. It's much more reasonable!

I don't know why you also remove the function "set_dev_node()" ? As I 
know, the
function just be called here. I think it should remain in your new function
pcibios_add_device().

Regards,
Yuanquan

>


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