[Nouveau] [PATCH 3/3] pci/gk104: wait for ltssm idle before changing the link

[Karol Herbst]

On Thu, Sep 12, 2019 at 9:07 PM Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>
> On Thu, Sep 12, 2019 at 3:00 PM Karol Herbst <kherbst at redhat.com> wrote:
> >
> > taken from nvgpu
> >
> > Signed-off-by: Karol Herbst <kherbst at redhat.com>
> > ---
> >  drm/nouveau/nvkm/subdev/pci/gk104.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drm/nouveau/nvkm/subdev/pci/gk104.c b/drm/nouveau/nvkm/subdev/pci/gk104.c
> > index 6aeb07fe4..2d1fa67eb 100644
> > --- a/drm/nouveau/nvkm/subdev/pci/gk104.c
> > +++ b/drm/nouveau/nvkm/subdev/pci/gk104.c
> > @@ -23,6 +23,8 @@
> >   */
> >  #include "priv.h"
> >
> > +#include <subdev/timer.h>
> > +
> >  static int
> >  gk104_pcie_version_supported(struct nvkm_pci *pci)
> >  {
> > @@ -142,6 +144,11 @@ gk104_pcie_set_link_speed(struct nvkm_pci *pci, enum nvkm_pcie_speed speed)
> >                 break;
> >         }
> >
> > +       /* wait for ltssm idle */
> > +       nvkm_msec(device, 200,
> > +               if ((nvkm_rd32(device, 0x8c040) & 0x1f) == 0)
> > +                       break;
> > +       );
>
> What if it doesn't idle? Should you still do the below things?
>

ohh, good point. I totally didn't think about that. nvgpu aborts the
operation of course and we should do the same.

> >         nvkm_mask(device, 0x8c040, 0xc0000, mask_value);
> >         nvkm_mask(device, 0x8c040, 0x1, 0x1);
> >  }
> > --
> > 2.21.0
> >
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