linux-kernel - Re: [PATCH v5 0/3] drm/nouveau: set DMA mask before mapping scratch page

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Date:   Tue, 18 Oct 2016 09:36:10 +0900
From:   Alexandre Courbot <gnurou@...il.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     David Airlie <airlied@...ux.ie>, Ben Skeggs <bskeggs@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v5 0/3] drm/nouveau: set DMA mask before mapping scratch page

On Mon, Oct 17, 2016 at 5:12 AM, Ard Biesheuvel
<ard.biesheuvel@...aro.org> wrote:
> On 7 October 2016 at 09:12, Alexandre Courbot <gnurou@...il.com> wrote:
>> On Fri, Oct 7, 2016 at 12:49 AM, Ard Biesheuvel
>> <ard.biesheuvel@...aro.org> wrote:
>>> This v4 is now a 3 piece series (since v4), after Alexandre pointed out that
>>> both GF 100 and NV50 are affected by the same issue, and that a related issue
>>> has been solved already for Tegra in commit 9d0394c6bed5
>>> ("drm/nouveau/instmem/gk20a: set DMA mask early").
>>>
>>> The issue that this series addresses is the fact that the Nouveau driver
>>> invokes the DMA API before setting the DMA mask. In both cases addressed
>>> here, these are simply static bidirectional mappings of scratch pages whose
>>> purpose is not well understood, and in most cases, it does not matter that
>>> these pages are always allocated below 4 GB even if the hardware can access
>>> memory much higher up.
>>>
>>> However, on platforms without any RAM below 4 GB, the preliminary DMA mask
>>> of 32 is preventing the nouveau driver from loading on GF100 and NV50
>>> hardware with an error like the following one:
>>>
>>>    nouveau 0000:02:00.0: enabling device (0000 -> 0003)
>>>    nouveau 0000:02:00.0: NVIDIA GT218 (0a8280b1)
>>>    nouveau 0000:02:00.0: bios: version 70.18.a6.00.00
>>>    nouveau 0000:02:00.0: fb ctor failed, -14
>>>    nouveau: probe of 0000:02:00.0 failed with error -14
>>>
>>> So fix this by setting a preliminary DMA mask based on the MMU device 'dma_bits'
>>> property (patch #1), and postpone mapping the scratch pages to the respective
>>> FB .init() hooks. (#2 and #3)
>>>
>>> v5: move setting of preliminary DMA mask to nvkm_device_pci_new() (#1)
>>>     move allocation and DMA mapping of scratch pages to .oneinit hooks (#2, #3)
>>> v4: split and move dma_set_mask to probe hook (Alexander)
>>> v3: rework code to get rid of DMA_ERROR_CODE references, which is not
>>>     defined on all architectures
>>> v2: replace incorrect comparison of dma_addr_t type var against NULL
>>>
>>> Ard Biesheuvel (3):
>>>   drm/nouveau: set streaming DMA mask early
>>>   drm/nouveau/fb/gf100: defer DMA mapping of scratch page to oneinit()
>>>     hook
>>>   drm/nouveau/fb/nv50: defer DMA mapping of scratch page to oneinit()
>>>     hook
>>
>> The series,
>>
>> Reviewed-by: Alexandre Courbot <acourbot@...dia.com>
>>
>
> Thank you Alexandre.
>
> So is there a nouveau subtree this should go into? Or is it up to Dave
> to pull it into drm?

Ben already merged your patches into
https://github.com/skeggsb/nouveau/commits/master (and forgot to add
my Reviewed-by ;)). This repository will be merged into the next
kernel release.