[Intel-gfx] [PATCH] drm/i915: Don't try to handle GuC when GuC is not supported.

[Jani Nikula]

On Thu, 06 Oct 2016, Paulo Zanoni <paulo.r.zanoni at intel.com> wrote:
> Em Qua, 2016-10-05 às 23:37 +0000, Vivi, Rodrigo escreveu:
>> Hi Daniel,
>> 
>> So, can we close https://bugs.freedesktop.org/show_bug.cgi?id=97573
>> with
>> wontfix or notabug?
>> 
>> I don't have a strong side on that actually, but Jani was against it
>> it
>> seems.
>
> Just my opinion:
>
> Considering that we already identified the problem and the fix is
> simple, I really think it's better to just fix it. In fact I thought
> you were going to submit V2 and I was planning to do the review.
>
> Fixing this may help reducing future bug triaging time, because if we
> keep the problem unfixed we may get the same bug report again and again
> and again. It's easy to say "users get to keep all the pieces of the
> broken kernel", but we usually have to triage the problems regardless,
> discuss what to do, etc.

All, please stop the discussion and just do one or the other. I'll ack
either approach.

http://dilbert.com/strip/1998-11-10


BR,
Jani.



>
>> 
>> Thanks,
>> Rodrigo.
>> 
>> On Wed, 2016-10-05 at 15:50 +0200, Daniel Vetter wrote:
>> > 
>> > On Thu, Sep 22, 2016 at 04:55:07PM +0000, Vivi, Rodrigo wrote:
>> > > 
>> > > On Wed, 2016-09-21 at 18:00 -0300, Paulo Zanoni wrote:
>> > > > 
>> > > > Em Qua, 2016-09-21 às 11:22 -0700, Rodrigo Vivi escreveu:
>> > > > > 
>> > > > > Avoid any kind of GuC handling if GuC is not supported
>> > > > > on a giving platform.
>> > > > > 
>> > > > > Besides being useless handling, our driver needs
>> > > > > to be smarter than the user trying to use an invalid
>> > > > > paramenter.
>> > > > 
>> > > > So the problem is when a platform doesn't support guc and the
>> > > > user
>> > > > passes i915.enable_guc_something=1, right?
>> > > 
>> > > 1 is not a problem actually since it means "use if available".
>> > > There is
>> > > not firmware and execution continues.
>> > > 
>> > > 2 is the problem because it means "use guc or fail if not
>> > > available".
>> > > But platforms that don't have guc can't fail. driver needs to be
>> > > smarter
>> > > than that.
>> > 
>> > Not sure it needs to be smarter than that really, since all these
>> > debug
>> > options auto-taint the kernel if you touch them. As in: You get to
>> > keep
>> > all the pieces.
>> > 
>> > We can still do some auto-cleanup of modoptions ofc if there's a
>> > good need
>> > for them.
>> > -Daniel
>> > 
>> > > 
>> > > 
>> > > > 
>> > > > 
>> > > > > 
>> > > > > 
>> > > > > Cc: Jani Nikula <jani.nikula at intel.com>
>> > > > > Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
>> > > > > Cc: Christophe Prigent <christophe.prigent at intel.com>
>> > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97573
>> > > > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> > > > > ---
>> > > > >  drivers/gpu/drm/i915/intel_guc_loader.c | 7 +++++++
>> > > > >  1 file changed, 7 insertions(+)
>> > > > > 
>> > > > > diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c
>> > > > > b/drivers/gpu/drm/i915/intel_guc_loader.c
>> > > > > index 6fd39ef..da0f5ed 100644
>> > > > > --- a/drivers/gpu/drm/i915/intel_guc_loader.c
>> > > > > +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
>> > > > > @@ -720,6 +720,13 @@ void intel_guc_init(struct drm_device
>> > > > > *dev)
>> > > > >  	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
>> > > > >  	const char *fw_path;
>> > > > >  
>> > > > > +	if (!HAS_GUC(dev)) {
>> > > > > +		i915.enable_guc_loading = 0;
>> > > > > +		i915.enable_guc_submission = 0;
>> > > > > +		fw_path = NULL;
>> > > > > +		return;
>> > > > > +	}
>> > > > 
>> > > > Instead of this, how about we just patch the code below with:
>> > > > 
>> > > > if (!HAS_GUC(dev_priv)) {
>> > > > 	i915.enable_guc_loading = 0;
>> > > > 	i915.enable_guc_submission = 0;
>> > > > } else {
>> > > > 	/* A negative value means "use platform default" */
>> > > > 	if (i915.enable_guc_loading < 0)
>> > > > 		i915.enable_guc_loading =
>> > > > HAS_GUC_UCODE(dev_priv);
>> > > > 	if (i915.enable_guc_submission < 0)
>> > > > 		i915.enable_guc_submission =
>> > > > HAS_GUC_SCHED(dev_priv);
>> > > > }
>> > > 
>> > > yeap, this works as well. I just went for the simplest option
>> > > that
>> > > minimized at most any interactions for platforms where GuC simply
>> > > doesn't exist.
>> > > 
>> > > > 
>> > > > 
>> > > > Or we could even go with our current "design pattern" and
>> > > > create
>> > > > intel_sanitize_guc_options().
>> > > 
>> > > This is indeed a very good idea.
>> > > 
>> > > > 
>> > > > 
>> > > > This way we'll be able to avoid adding a second failure code
>> > > > path,
>> > > > since we already have one for platforms with guc but options
>> > > > disabled.
>> > > > 
>> > > > 
>> > > > > 
>> > > > > +
>> > > > >  	/* A negative value means "use platform default" */
>> > > > >  	if (i915.enable_guc_loading < 0)
>> > > > >  		i915.enable_guc_loading =
>> > > > > HAS_GUC_UCODE(dev);
>> > > 
>> > > _______________________________________________
>> > > Intel-gfx mailing list
>> > > Intel-gfx at lists.freedesktop.org
>> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> > 
>> 

-- 
Jani Nikula, Intel Open Source Technology Center