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

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 07/04/2022 21:49, John Harrison wrote:
> 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.

You are right, I was on a kernel where DG1 wasn't yet defaulting to GuC 
hence the confusion when I tried to pass enable_guc=3 that broke TGL as 
well, but because I had no up to date firmware for it.

We really need per device modparams, as long as we have modparams..

Regards,

Tvrtko