[Nouveau] [PATCH] disp/gf119-: avoid creating non-existent heads

[Ilia Mirkin]

On Mon, Jul 3, 2017 at 6:02 PM, Ben Skeggs <skeggsb at gmail.com> wrote:
> On 07/04/2017 03:06 AM, Ilia Mirkin wrote:
>> We assume that each board has 4 heads for GF119+. However this is not
>> necessarily true - in the case of a GP108 board, the register indicated
>> that there were only 2.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101601
>> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
>> ---
>>
>> I'm not extremely happy about the fact that we have to duplicate the head count
>> in both the nv50_display logic for creating DRM-side CRTC's, as well as the
>> nvkm-side logic for creating heads. However I don't immediately see an easy way
>> around it without creating a nvif ioctl to get the number of heads.
> Yeah, I have WIP stuff from long ago that would make this nicer, but for
> now it's fine to do what you've done here.
>
>>
>>  drm/nouveau/nv50_display.c               | 8 +++++---
>>  drm/nouveau/nvkm/engine/disp/gf119.c     | 2 +-
>>  drm/nouveau/nvkm/engine/disp/headgf119.c | 4 +++-
>>  3 files changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/drm/nouveau/nv50_display.c b/drm/nouveau/nv50_display.c
>> index e3132a2c..e2170efb 100644
>> --- a/drm/nouveau/nv50_display.c
>> +++ b/drm/nouveau/nv50_display.c
>> @@ -4443,11 +4443,13 @@ nv50_display_create(struct drm_device *dev)
>>
>>       /* create crtc objects to represent the hw heads */
>>       if (disp->disp->oclass >= GF110_DISP)
>> -             crtcs = nvif_rd32(&device->object, 0x022448);
>> +             crtcs = nvif_rd32(&device->object, 0x612004) & 0xf;
>>       else
>> -             crtcs = 2;
>> +             crtcs = 0x3;
>>
>> -     for (i = 0; i < crtcs; i++) {
>> +     for (i = 0; i < fls(crtcs); i++) {
>> +             if (!(crtcs & (1 << i)))
>> +                     continue;
>>               ret = nv50_head_create(dev, i);
>>               if (ret)
>>                       goto out;
>> diff --git a/drm/nouveau/nvkm/engine/disp/gf119.c b/drm/nouveau/nvkm/engine/disp/gf119.c
>> index d8765b57..415987e9 100644
>> --- a/drm/nouveau/nvkm/engine/disp/gf119.c
>> +++ b/drm/nouveau/nvkm/engine/disp/gf119.c
>> @@ -168,7 +168,7 @@ int
>>  gf119_disp_new_(const struct nv50_disp_func *func, struct nvkm_device *device,
>>               int index, struct nvkm_disp **pdisp)
>>  {
>> -     u32 heads = nvkm_rd32(device, 0x022448);
>> +     u32 heads = fls(nvkm_rd32(device, 0x612004) & 0xf);
>>       return nv50_disp_new_(func, device, index, heads, pdisp);
> I'd drop this change.  I suspect 0x022448 is still the "maximum head
> count" register, and that 0x612004 is just a disable mask.

I suspect you're right (it's 4 as expected on the GP108 in question).
I think I was trying to avoid creating phantom heads, but the code in
headgf119.c will prevent that and ultimately have an identical effect.

Feel free to drop this hunk when applying.

>
>>  }
>>
>> diff --git a/drm/nouveau/nvkm/engine/disp/headgf119.c b/drm/nouveau/nvkm/engine/disp/headgf119.c
>> index b3355275..8d44bdf6 100644
>> --- a/drm/nouveau/nvkm/engine/disp/headgf119.c
>> +++ b/drm/nouveau/nvkm/engine/disp/headgf119.c
>> @@ -92,5 +92,7 @@ gf119_head = {
>>  int
>>  gf119_head_new(struct nvkm_disp *disp, int id)
>>  {
>> -     return nvkm_head_new_(&gf119_head, disp, id);
>> +     if (nvkm_rd32(disp->engine.subdev.device, 0x612004) & 0xf & (1 << id))
>> +             return nvkm_head_new_(&gf119_head, disp, id);
>> +     return 0;
>>  }
>>
>
>
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