linux-kernel - Re: [PATCH] amdgpu/uvd: use kmemdup

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Message-ID: <573DACCB.5030604@amd.com>
Date:	Thu, 19 May 2016 14:08:43 +0200
From:	Christian König <christian.koenig@....com>
To:	Muhammad Falak R Wani <falakreyaz@...il.com>
CC:	David Airlie <airlied@...ux.ie>,
	Alex Deucher <alexander.deucher@....com>,
	Chunming Zhou <David1.Zhou@....com>,
	Jammy Zhou <Jammy.Zhou@....com>, Leo Liu <leo.liu@....com>,
	Sonny Jiang <sonny.jiang@....com>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] amdgpu/uvd: use kmemdup

Am 19.05.2016 um 13:49 schrieb Muhammad Falak R Wani:
> On Thu, May 19, 2016 at 01:18:10PM +0200, Christian König wrote:
>> Am 19.05.2016 um 13:11 schrieb Muhammad Falak R Wani:
>>> Use kmemdup when some other buffer is immediately copied into allocated
>>> region. It replaces call to allocation followed by memcpy, by a single
>>> call to kmemdup.
>>>
>>> Signed-off-by: Muhammad Falak R Wani <falakreyaz@...il.com>
>> NAK, actually using memcpy() is wrong in the first place.
>>
>> The UVD BO is in VRAM so the pointer is pointing to IO memory here,
>> so this should be memcpy_fromio() instead of memcpy().
>>
>> Christian.
>>
> Should I send V2 with the required changes, and I had a query,

I can take care of fixing this.

> If memcpy was wrong, did it still work or it just got un-noticed ?

Both, on X86 memcpy from IO memory works fine. Only on other 
architectures you run into problems with that.

Regards,
Christian.