Re: [Intel-gfx] [PATCH] drm/i915: Add i915.enable_sagv modparam

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Mar 22, 2023 at 11:22:56PM +0200, Ville Syrjälä wrote:
> On Wed, Mar 22, 2023 at 04:36:09PM -0400, Rodrigo Vivi wrote:
> > On Wed, Mar 22, 2023 at 08:12:19PM +0200, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > Currently we have no sane way to forcibly disable SAGV, which
> > > makes debugging things a PITA. Manually poking at the pcode
> > > mailbox with it's various SAGV/QGV/PSF formats is no fun,
> > > and likely to be clobbered by the driver anyway.
> > > 
> > > Let's add a modparam for this.
> > > 
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/skl_watermark.c | 4 ++++
> > >  drivers/gpu/drm/i915/i915_params.c           | 3 +++
> > >  drivers/gpu/drm/i915/i915_params.h           | 1 +
> > >  3 files changed, 8 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> > > index 50a9a6adbe32..ff70225c0263 100644
> > > --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> > > +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> > > @@ -411,6 +411,9 @@ static bool intel_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state
> > >  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > >  	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> > >  
> > > +	if (!i915->params.enable_sagv)
> > > +		return false;
> > 
> > would this be one more ifdef for xe?
> 
> Why? xe needs it just as much.

yes, I know... but the param will be different...
open like this we need to have ifdef, or we need to hide in a macro,
or have it in a xe/ext/display/ duplicated file...

it was a comment more to raise the thoughts around items like this
that impacts xe... definitely not a blocker or anything like that...

> 
> > should we hide this on a HAS_SAGV?
> 
> If we have no sagv then we're not going to enable sagv anyway.
> Doesn't matter if it's blocked a few lines earlier by the
> modparam rather than falling through to checking the other
> stuff.
> 
> > 
> > anyway, let's move on:
> > 
> > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> 
> Thanks
> 
> > 
> > 
> > > +
> > >  	if (DISPLAY_VER(i915) >= 12)
> > >  		return tgl_crtc_can_enable_sagv(crtc_state);
> > >  	else
> > > @@ -3696,6 +3699,7 @@ static int intel_sagv_status_show(struct seq_file *m, void *unused)
> > >  	};
> > >  
> > >  	seq_printf(m, "SAGV available: %s\n", str_yes_no(intel_has_sagv(i915)));
> > > +	seq_printf(m, "SAGV modparam: %s\n", str_enabled_disabled(i915->params.enable_sagv));
> > >  	seq_printf(m, "SAGV status: %s\n", sagv_status[i915->display.sagv.status]);
> > >  	seq_printf(m, "SAGV block time: %d usec\n", i915->display.sagv.block_time_us);
> > >  
> > > diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> > > index ade744cccfea..66141906ea05 100644
> > > --- a/drivers/gpu/drm/i915/i915_params.c
> > > +++ b/drivers/gpu/drm/i915/i915_params.c
> > > @@ -121,6 +121,9 @@ i915_param_named_unsafe(enable_psr2_sel_fetch, bool, 0400,
> > >  	"(0=disabled, 1=enabled) "
> > >  	"Default: 0");
> > >  
> > > +i915_param_named_unsafe(enable_sagv, bool, 0600,
> > > +	"Enable system agent voltage/frequency scaling (SAGV) (default: true)");
> > > +
> > >  i915_param_named_unsafe(force_probe, charp, 0400,
> > >  	"Force probe options for specified supported devices. "
> > >  	"See CONFIG_DRM_I915_FORCE_PROBE for details.");
> > > diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> > > index 3f51f90145b6..6798b5c2363d 100644
> > > --- a/drivers/gpu/drm/i915/i915_params.h
> > > +++ b/drivers/gpu/drm/i915/i915_params.h
> > > @@ -56,6 +56,7 @@ struct drm_printer;
> > >  	param(int, enable_psr, -1, 0600) \
> > >  	param(bool, psr_safest_params, false, 0400) \
> > >  	param(bool, enable_psr2_sel_fetch, true, 0400) \
> > > +	param(bool, enable_sagv, true, 0600) \
> > >  	param(int, disable_power_well, -1, 0400) \
> > >  	param(int, enable_ips, 1, 0600) \
> > >  	param(int, invert_brightness, 0, 0600) \
> > > -- 
> > > 2.39.2
> > > 
> 
> -- 
> Ville Syrjälä
> Intel