Re: [PATCH 1/1] drm/i915/uc: Use platform specific defaults for GuC/HuC enabling

[John Harrison <john.c.harrison@xxxxxxxxx>]

On 4/7/2022 08:49, Tvrtko Ursulin wrote:
> On 03/06/2021 17:48, Matthew Brost wrote:
> > From: John Harrison <John.C.Harrison@xxxxxxxxx>
> >
> > The meaning of 'default' for the enable_guc module parameter has been
> > updated to accurately reflect what is supported on current platforms.
> > So start using the defaults instead of forcing everything off.
> > Although, note that right now, the default is for everything to be off
> > anyway. So this is not a change for current platforms.
> >
> > Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
> > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/i915_params.c | 2 +-
> >   drivers/gpu/drm/i915/i915_params.h | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_params.c 
> > b/drivers/gpu/drm/i915/i915_params.c
> > index 0320878d96b0..e07f4cfea63a 100644
> > --- a/drivers/gpu/drm/i915/i915_params.c
> > +++ b/drivers/gpu/drm/i915/i915_params.c
> > @@ -160,7 +160,7 @@ i915_param_named_unsafe(edp_vswing, int, 0400,
> >   i915_param_named_unsafe(enable_guc, int, 0400,
> >       "Enable GuC load for GuC submission and/or HuC load. "
> >       "Required functionality can be selected using bitmask values. "
> > -    "(-1=auto, 0=disable [default], 1=GuC submission, 2=HuC load)");
> > +    "(-1=auto [default], 0=disable, 1=GuC submission, 2=HuC load)");
> >     i915_param_named(guc_log_level, int, 0400,
> >       "GuC firmware logging level. Requires GuC to be loaded. "
> > diff --git a/drivers/gpu/drm/i915/i915_params.h 
> > b/drivers/gpu/drm/i915/i915_params.h
> > index 4a114a5ad000..f27eceb82c0f 100644
> > --- a/drivers/gpu/drm/i915/i915_params.h
> > +++ b/drivers/gpu/drm/i915/i915_params.h
> > @@ -59,7 +59,7 @@ struct drm_printer;
> >       param(int, disable_power_well, -1, 0400) \
> >       param(int, enable_ips, 1, 0600) \
> >       param(int, invert_brightness, 0, 0600) \
> > -    param(int, enable_guc, 0, 0400) \
> > +    param(int, enable_guc, -1, 0400) \
> >       param(int, guc_log_level, -1, 0400) \
> >       param(char *, guc_firmware_path, NULL, 0400) \
> >       param(char *, huc_firmware_path, NULL, 0400) \
>
> What is the BKM to use this with multi-GPU setups? Specifically I have 
> a TGL+DG1 laptop (off the shelf) and want to have GuC with DG1 only. 
> If I pass i915.enable_guc=3 it seems it wants to enable it for TGL as 
> well and wedges the GPU if it can't?
I don't think there is one.

Module parameters are driver global and therefore apply to all cards in 
the system, both discrete and integrated. The '-1' default can and does 
have different meanings for each card. So in the TGL+DG1 case, TGL 
should default to execlist and DG1 should already be defaulting to GuC. 
So the -1 setting should do what you want. But if you did need to 
override for one specific card only then I think you would need to do 
that with a code change and rebuild.

John.


> Regards,
>
> Tvrtko