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

[Ilia Mirkin]

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?

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