[Nouveau] [PATCH v3 1/6] make RAM device optional

[Alexandre Courbot]

On Thu, Feb 19, 2015 at 11:20 AM, Ben Skeggs <skeggsb at gmail.com> wrote:
> On 18 Feb 2015 17:08, "Alexandre Courbot" <gnurou at gmail.com> wrote:
>>
>> On Wed, Feb 18, 2015 at 8:01 AM, Ben Skeggs <skeggsb at gmail.com> wrote:
>> > On Tue, Feb 17, 2015 at 5:47 PM, Alexandre Courbot <acourbot at nvidia.com>
>> > wrote:
>> >> Having a RAM device does not make sense for chips like GK20A which have
>> >> no dedicated video memory. The dummy RAM device that we used so far
>> >> works as a temporary band-aid, but in the long-term it is desirable for
>> >> the driver to be able to work without any kind of VRAM.
>> >>
>> >> This patch adds a few conditionals in places where a RAM device was
>> >> assumed to be present and allows some more objects to be allocated from
>> >> the TT domain, allowing Nouveau to handle GPUs for which
>> >> pfb->ram == NULL.
>> >>
>> >> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
>> >> ---
>> >>  drm/nouveau/nouveau_display.c         |  8 +++++++-
>> >>  drm/nouveau/nouveau_ttm.c             |  3 +++
>> >>  drm/nouveau/nv84_fence.c              | 14 +++++++++++---
>> >>  drm/nouveau/nvkm/engine/device/base.c |  9 ++++++---
>> >>  drm/nouveau/nvkm/subdev/clk/base.c    |  2 +-
>> >>  drm/nouveau/nvkm/subdev/fb/base.c     | 26 ++++++++++++++++++--------
>> >>  drm/nouveau/nvkm/subdev/ltc/gf100.c   | 10 +++++++++-
>> >>  7 files changed, 55 insertions(+), 17 deletions(-)
>> >>
>> >> diff --git a/drm/nouveau/nouveau_display.c
>> >> b/drm/nouveau/nouveau_display.c
>> >> index 860b0e2d4181..68ee0af22eea 100644
>> >> --- a/drm/nouveau/nouveau_display.c
>> >> +++ b/drm/nouveau/nouveau_display.c
>> >> @@ -869,13 +869,19 @@ nouveau_display_dumb_create(struct drm_file
>> >> *file_priv, struct drm_device *dev,
>> >>                             struct drm_mode_create_dumb *args)
>> >>  {
>> >>         struct nouveau_bo *bo;
>> >> +       uint32_t domain;
>> >>         int ret;
>> >>
>> >>         args->pitch = roundup(args->width * (args->bpp / 8), 256);
>> >>         args->size = args->pitch * args->height;
>> >>         args->size = roundup(args->size, PAGE_SIZE);
>> >>
>> >> -       ret = nouveau_gem_new(dev, args->size, 0,
>> >> NOUVEAU_GEM_DOMAIN_VRAM, 0, 0, &bo);
>> >> +       if (nvxx_fb(&nouveau_drm(dev)->device)->ram)
>> > For these checks in the drm, it's probably better to use
>> > nouveau_drm(dev)->device.info.ram_size.
>>
>> I wonder - in other places (e.g. clock, ltc) we don't have access to
>> nouveau_drm, so IIUC we need to rely on pfb->ram there.
> Correct.
>
>>Wouldn't it be
>> more confusing to use two different ways to check the presence of VRAM
>> when we could stick to a single one?
> It's best to think of nvkm/ as a separate entity, and it will be at some
> point (drm load on its own, inside a vm), and drm might not be able to
> access it's internal structures.
>
> That's not the case now, so the code is fine as-is for the moment. But it's
> worth keeping in mind.

Thanks for clarifying! I will update according to your suggestion.