Re: [Intel-gfx] [PATCH] drm/i915/mtl: Copy c10 phy pll sw state from master to slave for bigjoiner

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Apr 21, 2023 at 02:37:11PM +0300, Lisovskiy, Stanislav wrote:
> On Fri, Apr 21, 2023 at 12:26:08PM +0300, Ville Syrjälä wrote:
> > On Fri, Apr 21, 2023 at 11:35:20AM +0300, Stanislav Lisovskiy wrote:
> > > We try to verify pll registers in sw state for slave crtc with the hw state.
> > > However in case of bigjoiner we don't calculate those at all, so this verification
> > > will then always fail.
> > > So we should either skip the verification for Bigjoiner slave crtc or copy sw state
> > > from master crtc.
> > > 
> > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > > index bf391a6cd8d6..83c98791fea3 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -4556,6 +4556,7 @@ copy_bigjoiner_crtc_state_modeset(struct intel_atomic_state *state,
> > >  	drm_mode_copy(&slave_crtc_state->hw.adjusted_mode,
> > >  		      &master_crtc_state->hw.adjusted_mode);
> > >  	slave_crtc_state->hw.scaling_filter = master_crtc_state->hw.scaling_filter;
> > > +	slave_crtc_state->cx0pll_state = master_crtc_state->cx0pll_state;
> > 
> > Wrong place. Also we're already copying dpll_hw_state which is in the
> > same union, and on first blush looks bigger than this thing. So why is
> > that not working?
> 
> No we aren't copying it, we are "saving" it earlier, however it doesn't help at all:
> 
> /* preserve some things from the slave's original crtc state */
> saved_state->uapi = slave_crtc_state->uapi;
> saved_state->scaler_state = slave_crtc_state->scaler_state;
> saved_state->shared_dpll = slave_crtc_state->shared_dpll;
> saved_state->dpll_hw_state = slave_crtc_state->dpll_hw_state;

Hmm. How is anything at all working if we keep this around
from the old state?

Looks like I probably broke this in
commit 0ff0e219d9b8 ("drm/i915: Compute clocks earlier")
and somehow no one has noticed.

The correct fix would seem to be to just nuke that
dpll_hw_state preservation above.


> saved_state->crc_enabled = slave_crtc_state->crc_enabled;
> 
> intel_crtc_free_hw_state(slave_crtc_state);
> memcpy(slave_crtc_state, saved_state, sizeof(*slave_crtc_state));
> kfree(saved_state);
> 
> /* Re-init hw state */
> memset(&slave_crtc_state->hw, 0, sizeof(slave_crtc_state->hw));
> slave_crtc_state->hw.enable = master_crtc_state->hw.enable;
> slave_crtc_state->hw.active = master_crtc_state->hw.active;
> 
> because I guess it just didn't have that stuff initially.
> 
> It starts to work without those verify WARN's only if I copy it from master_crtc_state.
> 
> Stan
> 
> > 
> > >  
> > >  	copy_bigjoiner_crtc_state_nomodeset(state, slave_crtc);
> > >  
> > > -- 
> > > 2.37.3
> > 
> > -- 
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel