[Nouveau] [PATCH] Accept 3d controllers and not only VGA controllers.
Josef Larsson
josef.lar at gmail.com
Mon Dec 18 17:30:59 UTC 2017
Without a NULL pointer safe-guard patch, I get a kernel oops when I plug
in external displays in my docking station, (exactly the same issue as
https://bugs.freedesktop.org/show_bug.cgi?id=101778) and without
removing or modifying the check (accepting PCI_CLASS_DISPLAY_3D in the
if-condition), I cannot use external displays through my docking
station. This is on an optimus system where I use reverse PRIME to be
able to use the connectors at all. Having some kind of safe-guard makes
sense to me, and that is available in the i915-driver of the
corresponding functions.
If there are better patches to fix my two problems, I am willing to try
them out, because I really think this should be handled somehow.
One note though: These patches do not make the docking station
experience perfect. They only make it not quite as bad. For example,
undocking when using external displays forces Xorg to restart, and when
docking without a patch for xf86-video-nouveau DDX by Ilia Mirkin
(https://people.freedesktop.org/~imirkin/patches/0001-drmmode-update-logic-for-dynamic-connectors-paths-an.patch),
the external docking station displays are not detected.
On 2017-12-14 23:59, Karol Herbst wrote:
>
> On 14 December 2017 11:55:35 p.m. GMT+01:00, Ben Skeggs <skeggsb at gmail.com> wrote:
>> On 14 December 2017 at 23:45, Tobias Klausmann
>> <tobias.johannes.klausmann at mni.thm.de> wrote:
>>> On 12/3/17 8:56 PM, Josef Larsson wrote:
>>>> Sure, I can easily split it into two commits, but I would like to
>> have
>>>> an OK on the actual code changes before splitting the patch.
>> I'm not actually sure this is a good idea still. As I recall, part of
>> the purpose of that check is to prevent nouveau taking over as the
>> primary fbcon when it's the secondary display in the system. ie.
>> Optimus system with Intel driving the display, NVIDIA GPU has no
>> displays attached. If nouveau loads first, at some point in history,
>> you'd have ended up with a blank console.
>>
>> I'm not sure if this is still the case, but it warrants checking
>> before making this change.
>>
>> I'm more interested in what this actually solves, and why not having
>> fbcon prevents external displays from being used.
>>
>> Ben.
>>
> I think the issue is we can't really put any trust in this. my kepler GPU on my laptop is a VGA device, not a 3D accelerator, even though everything is wird to intel, it is a MXM card though, so in theory it is able to drive displays.
>
> We need something else to detect if the GPU is the main one or not.
>
>>>> Best regards,
>>>>
>>>> Josef Larsson
>>>>
>>>>
>>>> On 2017-11-11 01:05, Tobias Klausmann wrote:
>>>>> On 11/10/17 7:49 PM, Josef Larsson wrote:
>>>>>> Accept 3d controllers and not only VGA controllers. According to
>> Ilia
>>>>>> Mirkin,
>>>>>> the VGA controller check should be removed. This makes it possible
>>>>>> to use external connectors on a docking station (40A5) for a
>> Thinkpad
>>>>>> P51.
>>>>>> (See Bug 101778).
>>>>>>
>>>>>> lspci example:
>>>>>>
>>>>>> 01:00.0 3D controller: NVIDIA Corporation GM107GLM [Quadro M1200
>> Mobile]
>>>>>> (rev a2)
>>>>>>
>>>>>> Also include safe-guards to avoid NULL dereferencing of fbcon,
>> which is
>>>>>> how this bug was found.
>>>>>> ---
>>>>>> drivers/gpu/drm/nouveau/nouveau_fbcon.c | 3 +--
>>>>>> drivers/gpu/drm/nouveau/nv50_display.c | 13 +++++++++++++
>>>>>> 2 files changed, 14 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
>>>>>> b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
>>>>>> index 2b12d82aac15..6b4d374a9d82 100644
>>>>>> --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
>>>>>> +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
>>>>>> @@ -498,8 +498,7 @@ nouveau_fbcon_init(struct drm_device *dev)
>>>>>> int preferred_bpp;
>>>>>> int ret;
>>>>>> - if (!dev->mode_config.num_crtc ||
>>>>>> - (dev->pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
>>>>>> + if (!dev->mode_config.num_crtc)
>>>>>> return 0;
>>>>>> fbcon = kzalloc(sizeof(struct nouveau_fbdev),
>> GFP_KERNEL);
>>>>>> diff --git a/drivers/gpu/drm/nouveau/nv50_display.c
>>>>>> b/drivers/gpu/drm/nouveau/nv50_display.c
>>>>>> index fb47d46050ec..061daf036407 100644
>>>>>> --- a/drivers/gpu/drm/nouveau/nv50_display.c
>>>>>> +++ b/drivers/gpu/drm/nouveau/nv50_display.c
>>>>>> @@ -3214,6 +3214,13 @@ nv50_mstm_destroy_connector(struct
>>>>>> drm_dp_mst_topology_mgr *mgr,
>>>>>> struct nouveau_drm *drm = nouveau_drm(connector->dev);
>>>>>> struct nv50_mstc *mstc = nv50_mstc(connector);
>>>>>> + if (!drm->fbcon)
>>>>>> + {
>>>>>> + NV_WARN(drm, "drm->fbcon of %s point to NULL. Will not
>> destroy
>>>>>> connector\n",
>>>>>> + connector->name);
>>>>>> + return;
>>>>>> + }
>>>>>> +
>>>>>> drm_connector_unregister(&mstc->connector);
>>>>>> drm_modeset_lock_all(drm->dev);
>>>>>> @@ -3229,6 +3236,12 @@ nv50_mstm_register_connector(struct
>> drm_connector
>>>>>> *connector)
>>>>>> {
>>>>>> struct nouveau_drm *drm = nouveau_drm(connector->dev);
>>>>>> + if (!drm->fbcon)
>>>>>> + {
>>>>>> + NV_WARN(drm, "drm->fbcon of %s point to NULL. Will not
>> register
>>>>>> connector\n",
>>>>>> + connector->name);
>>>>>> + return;
>>>>>> + }
>>>>>> drm_modeset_lock_all(drm->dev);
>>>>>> drm_fb_helper_add_one_connector(&drm->fbcon->helper,
>> connector);
>>>>>> drm_modeset_unlock_all(drm->dev);
>>>>>>
>>>>>>
>>>>> Hi,
>>>>>
>>>>> the patch looks OK to me, yet as noted in IRC, i'd like to have
>> this
>>>>> patch split into two and have the ->fbcon check as a precondition
>> to
>>>>> the 3D Controller part. But lets see what the other and more clever
>>>>> people think about it! :)
>>>>>
>>>>> Greetings,
>>>>>
>>>>> Tobias
>>>>>
>>> Ping,
>>>
>>> adding Ben Skeggs and Dave Airlied to CC, maybe this will get this
>> little
>>> one commited!
>>>
>>>
>>> Greetings,
>>>
>>> Tobias
>>>
>>>
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