[Nouveau] [PATCH] nouveau: nv46: Change mc subdev oclass from nv44 to nv4c

[Ben Skeggs]

On 28 July 2015 at 01:52, Hans de Goede <hdegoede at redhat.com> wrote:
> Hi,
>
> On 24-07-15 04:32, Ben Skeggs wrote:
>>
>> On 24 July 2015 at 01:20, Hans de Goede <hdegoede at redhat.com> wrote:
>>>
>>> MSI interrupts appear to not work for nv46 based cards. Change the mc
>>> subdev oclass for these cards from nv44 to nv4c, the nv4c mc code is
>>> identical to the nv44 mc code except that it does not use msi
>>> (it does not define a msi_rearm callback).
>>
>> I'm fine with this, but it'd be nice to check that the binary driver
>> doesn't/can't use MSI on these too (there might be an alternate method
>> we need to use).
>>
>> Would you be able to grab the latest proprietary driver that works on
>> nv4x, and do a mmiotrace of it?
>
>
> I've grabbed 304.125
>
>> You *might* need to use "modprobe
>> nvidia NVreg_EnableMSI=1", because at some point NVIDIA didn't use it
>> by default anywhere.
>
>
> You're right I needed to specify NVreg_EnableMSI=1, with that set
> /proc/interrupts shows that MSI is used.
>
> Here is an of running glxgears with the binary driver using msi interrupts
> mmiotrace:
>
> https://fedorapeople.org/~jwrdegoede/nvidia-bin-nv46-msi-on-glxgears.mmiotrace.gz
>
> AFAIK there are some nouveau tools to parse this a bit, right ? I'm going
> to call it a day for today, if you can give me some pointers what to do with
> the
> mmiotrace to find a potential fix for the msi issues, that would be
> appreciated.
>
>
> BTW I had to build my own kernel with mmiotrace enabled in Kconfig, as this
> is disabled in the Fedora kernels by default. Do you know if there is a good
> reason to have this disabled by default, or should I ask the Fedora
> kernel maintainers to enable it by default ?
The -debug kernel has it enabled already.  However, it's also
problematic in that it enables various lockdep debugging stuff that
causes the binary driver kernel module to end up depending on GPL-only
symbols, which you have to hack around by changing the
MODULE_LICENSE() for the binary driver to "GPL"... Which is clearly a
pain :)  So, I guess if you want a slightly more straight-forward
approach, it'd be good to enable in the non-debug kernels too.

>
>
> Slightly offtopic:
>
> I decided to be bold and try gnome-shell on the nv46 with msi disabled,
> which sofar was a guaranteed way to freeze the system, and it now works
> somewhat (latest kernel, ddx and mesa). I see something which shows
> horizontal lines which are small parts from my desktop background, and
> things change significantly when I switch to the overview mode.
>
> But other then that the display is completely wrong, it looks a bit
> like a framebuffer pitch problem, but then different. I think it
> is likely some tiling problem or some such.
>
> Note that metacity + glxgears works, this only shows with
> gnome-shell, any hints where to start looking wrt debugging this?
These are the main issues that I'd like to see resolved :)

>
> Or should I first try to run piglet and see if some tests there
> point out the culprit?
I think this is a good place to start.

Thanks,
Ben.

>
>
> Regards,
>
> Hans
>
>
>
>>
>> Thanks,
>> Ben.
>>
>>> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=90435
>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>> ---
>>>   drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c
>>> b/drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c
>>> index c630136..b4ad791 100644
>>> --- a/drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c
>>> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c
>>> @@ -265,7 +265,7 @@ nv40_identify(struct nvkm_device *device)
>>>                  device->oclass[NVDEV_SUBDEV_CLK    ] = &nv40_clk_oclass;
>>>                  device->oclass[NVDEV_SUBDEV_THERM  ] =
>>> &nv40_therm_oclass;
>>>                  device->oclass[NVDEV_SUBDEV_DEVINIT] =
>>> nv1a_devinit_oclass;
>>> -               device->oclass[NVDEV_SUBDEV_MC     ] =  nv44_mc_oclass;
>>> +               device->oclass[NVDEV_SUBDEV_MC     ] =  nv4c_mc_oclass;
>>>                  device->oclass[NVDEV_SUBDEV_BUS    ] =  nv31_bus_oclass;
>>>                  device->oclass[NVDEV_SUBDEV_TIMER  ] =
>>> &nv04_timer_oclass;
>>>                  device->oclass[NVDEV_SUBDEV_FB     ] =  nv46_fb_oclass;
>>> --
>>> 2.4.3
>>>
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