linux-kernel - Re: [RFC PATCH] drm/nouveau/fb/nv50: set DMA mask before mapping scratch page

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Date:	Thu, 23 Jun 2016 13:57:42 +0100
From:	Punit Agrawal <punit.agrawal@....com>
To:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:	nouveau@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	bskeggs@...hat.com, airlied@...ux.ie,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] drm/nouveau/fb/nv50: set DMA mask before mapping scratch page

Ard Biesheuvel <ard.biesheuvel@...aro.org> writes:

> On 23 June 2016 at 11:55, Punit Agrawal <punit.agrawal@....com> wrote:
>> Ard Biesheuvel <ard.biesheuvel@...aro.org> writes:
>>
>>> The 100c08 scratch page is mapped using dma_map_page() before the TTM
>>> layer has had a chance to set the DMA mask. This means we are still
>>> running with the default of 32 when this code executes, and this causes
>>> problems for platforms with no memory below 4 GB (such as AMD Seattle)
>>>
>>> So move the dma_map_page() to the .init hook, and set the streaming DMA
>>> mask based on the MMU subdev parameters before performing the call.
>>>
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>>
>> Hi Ard,
>>
>> Thanks for posting this patch.
>>
>> With the patch, I am able to see console output on a screen attached to
>> the NVS 300 PCIe card in an AMD Seattle system. It was failing with
>> a message similar to what you've posted below.
>>
>
> Thanks for the report. May I take it as a tested-by?

Sure.

Punit


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