linux-kernel - Re: [PATCH v1] ARM:sa1100: Remove a redundant spin lock

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Message-ID: <53B3E6B4.2040907@windriver.com>
Date:	Wed, 2 Jul 2014 19:02:12 +0800
From:	"Yang,Wei" <Wei.Yang@...driver.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	<mroberto@...i.cetuc.puc-rio.br>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1] ARM:sa1100: Remove a redundant spin lock

On 07/02/2014 06:19 PM, Russell King - ARM Linux wrote:
> On Wed, Jul 02, 2014 at 05:19:40PM +0800, Yang,Wei wrote:
>> Hi Guys,
>>
>> What about this patch?
> The only concern on the face of it is that it removes mutual exclusion
> from the pci config write path, where a read-modifiy-write operation is
> performed.
>
> However, the PCI code already gives that guarantee (drivers/pci/access.c)
> so this should be safe.
>
> As this is fairly old code, it would be useful to know what the motivation
> is behind this change.  Is it purely clean up, or is it something that
> you've tested, or is this a change that you require for something else?
>
> Thanks.
>
Hmm, I fixed a bug of pci config read/write of an ARM board, but 
unfortunately, so far ML does not support it. So
I cannot send the fix, but I grepped the pci source code of ARM 
architecure, I found that the pci code of a few boards always
define a static spin lock to excluse the pci config read/write path. I 
just intended to clean up them. If you agree the change,
I want to send v2 to also remove this mutual exclusion for something 
else board which also used the mutual exclusion.

Thanks
Wei
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