linux-kernel - Re: [PATCH v2] dma: mmp_pdma: fix a memory alloc error

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Message-ID: <CACDNBm03v0KB_2XhUzKmi7c9BpfG1tSOUUNa549ETs=3FbZAvA@mail.gmail.com>
Date:	Thu, 1 Aug 2013 10:27:47 +0800
From:	Xiang Wang <wangxfdu@...il.com>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	Dan Williams <djbw@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	cxie4@...vell.com, Xiang Wang <wangx@...vell.com>
Subject: Re: [PATCH v2] dma: mmp_pdma: fix a memory alloc error

2013/7/29 Vinod Koul <vinod.koul@...el.com>:
> On Thu, Jul 25, 2013 at 10:22:50AM +0800, Xiang Wang wrote:
>
> Btw its generally a good idea to remove the parts not required for further
> discussion
>
>> Would you please explain a little more about why we should use
>> GFP_NOWAIT here? This memory is not dedicated for DMA controller. Do
>> we have special reasons to use GFP_NOWAIT? Thanks!
> There are few reasons
> - the dma requests can be triggered from atomic context
> - so for above you can argue to use the GFP_ATOMIC and the guideline for dma
>   drivers [1] was discussed briefly
>
> ~Vinod
> [1]: http://lkml.indiana.edu/hypermail/linux/kernel/0911.1/02316.html
>
> --
Hi, Vinod
Thanks for your explanation. But want to double confirm with you that
the memory alloc in my patch is in probe function, still need to use
GFP_NOWAIT? Thanks!

-- 
Regards,
Xiang
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