[PATCH] drm/amdgpu: Add kernel parameter to force no xgmi

[Kim, Jonathan]

[AMD Official Use Only - Internal Distribution Only]

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
> Luben Tuikov
> Sent: Wednesday, October 28, 2020 11:12 AM
> To: Sierra Guiza, Alejandro (Alex) <Alex.Sierra at amd.com>; amd-
> gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amdgpu: Add kernel parameter to force no xgmi
>
> [CAUTION: External Email]
>
> On 2020-10-28 10:55, Alex Sierra wrote:
> > By enabling this parameter, the system will be forced to use pcie
> > interface only for p2p transactions.
> >
> > Signed-off-by: Alex Sierra <alex.sierra at amd.com>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 +
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 9 +++++++++
> >  3 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > index ba65d4f2ab67..3645f00e9f61 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > @@ -188,6 +188,7 @@ extern int amdgpu_discovery;  extern int
> > amdgpu_mes;  extern int amdgpu_noretry;  extern int
> > amdgpu_force_asic_type;
> > +extern int amdgpu_force_no_xgmi;
> >  #ifdef CONFIG_HSA_AMD
> >  extern int sched_policy;
> >  extern bool debug_evictions;
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > index 1fe850e0a94d..0a5d97a84017 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > @@ -2257,7 +2257,7 @@ static int amdgpu_device_ip_init(struct
> amdgpu_device *adev)
> >       if (r)
> >               goto init_failed;
> >
> > -     if (adev->gmc.xgmi.num_physical_nodes > 1)
> > +     if (!amdgpu_force_no_xgmi && adev->gmc.xgmi.num_physical_nodes
> >
> > + 1)
> >               amdgpu_xgmi_add_device(adev);
> >       amdgpu_amdkfd_device_init(adev);
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > index 4b78ecfd35f7..22485067cf31 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > @@ -160,6 +160,7 @@ int amdgpu_force_asic_type = -1;  int amdgpu_tmz
> =
> > 0;  int amdgpu_reset_method = -1; /* auto */  int amdgpu_num_kcq = -1;
> > +int amdgpu_force_no_xgmi = 0;
> >
> >  struct amdgpu_mgpu_info mgpu_info = {
> >       .mutex = __MUTEX_INITIALIZER(mgpu_info.mutex),
> > @@ -522,6 +523,14 @@ module_param_named(ras_enable,
> amdgpu_ras_enable,
> > int, 0444);  MODULE_PARM_DESC(ras_mask, "Mask of RAS features to
> > enable (default 0xffffffff), only valid when ras_enable == 1");
> > module_param_named(ras_mask, amdgpu_ras_mask, uint, 0444);
> >
> > +/**
> > + * DOC: force_no_xgmi (uint)
> > + * Forces not to use xgmi interface (0 = disable, 1 = enable).
>
> How about using human English here? Perhaps something like,
>
> "Forces not to use" ==> "Disables the use of the XGMI interface ..."
>
> Or, if you use the suggestion Christian posted, you could say something like,
>
> "Enable XGMI for P2P transactions."

I second the use of enable.  The fact that we can prevent xGMI init means we enable it by default.

Thanks,

Jon

>
> Regards,
> Luben
>
> > + * Default is 0 (disabled).
> > + */
> > +MODULE_PARM_DESC(force_no_xgmi, "Force not to use xgmi
> interface");
> > +module_param_named(force_no_xgmi, amdgpu_force_no_xgmi, int,
> 0600);
> > +
> >  /**
> >   * DOC: si_support (int)
> >   * Set SI support driver. This parameter works after set config
> > CONFIG_DRM_AMDGPU_SI. For SI asic, when radeon driver is enabled,
> >
>
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