Re: [PATCH v2 7/7] drm/vc4: kms: Don't disable the muxing of an active CRTC

[Maxime Ripard <maxime@cerno.tech>]

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Hi!

On Mon, Nov 02, 2020 at 05:47:04PM +0900, Hoegeun Kwon wrote:
> Hi Maxime,
> 
> Thanks for V2 patch.
> 
> 
> On 10/28/20 9:41 PM, Maxime Ripard wrote:
> > The current HVS muxing code will consider the CRTCs in a given state to
> > setup their muxing in the HVS, and disable the other CRTCs muxes.
> >
> > However, it's valid to only update a single CRTC with a state, and in this
> > situation we would mux out a CRTC that was enabled but left untouched by
> > the new state.
> >
> > Fix this by setting a flag on the CRTC state when the muxing has been
> > changed, and only change the muxing configuration when that flag is there.
> >
> > Fixes: 87ebcd42fb7b ("drm/vc4: crtc: Assign output to channel automatically")
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > ---
> >   drivers/gpu/drm/vc4/vc4_drv.h |  1 +-
> >   drivers/gpu/drm/vc4/vc4_kms.c | 84 +++++++++++++++++++++---------------
> >   2 files changed, 50 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> > index c6208b040f77..c074c0538e57 100644
> > --- a/drivers/gpu/drm/vc4/vc4_drv.h
> > +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> > @@ -523,6 +523,7 @@ struct vc4_crtc_state {
> >   	struct drm_mm_node mm;
> >   	bool feed_txp;
> >   	bool txp_armed;
> > +	bool needs_muxing;
> >   	unsigned int assigned_channel;
> >   
> >   	struct {
> > diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> > index 2aa726b7422c..409aeb19d210 100644
> > --- a/drivers/gpu/drm/vc4/vc4_kms.c
> > +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> > @@ -224,10 +224,7 @@ static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
> >   {
> >   	struct drm_crtc_state *crtc_state;
> >   	struct drm_crtc *crtc;
> > -	unsigned char dsp2_mux = 0;
> > -	unsigned char dsp3_mux = 3;
> > -	unsigned char dsp4_mux = 3;
> > -	unsigned char dsp5_mux = 3;
> > +	unsigned char mux;
> >   	unsigned int i;
> >   	u32 reg;
> >   
> > @@ -235,50 +232,59 @@ static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
> >   		struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc_state);
> >   		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
> >   
> > -		if (!crtc_state->active)
> > +		if (!vc4_state->needs_muxing)
> >   			continue;
> >   
> >   		switch (vc4_crtc->data->hvs_output) {
> >   		case 2:
> > -			dsp2_mux = (vc4_state->assigned_channel == 2) ? 0 : 1;
> > +			mux = (vc4_state->assigned_channel == 2) ? 0 : 1;
> > +			reg = HVS_READ(SCALER_DISPECTRL);
> > +			HVS_WRITE(SCALER_DISPECTRL,
> > +				  (reg & ~SCALER_DISPECTRL_DSP2_MUX_MASK) |
> > +				  VC4_SET_FIELD(mux, SCALER_DISPECTRL_DSP2_MUX));
> >   			break;
> >   
> >   		case 3:
> > -			dsp3_mux = vc4_state->assigned_channel;
> > +			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
> > +				mux = 3;
> > +			else
> > +				mux = vc4_state->assigned_channel;
> > +
> > +			reg = HVS_READ(SCALER_DISPCTRL);
> > +			HVS_WRITE(SCALER_DISPCTRL,
> > +				  (reg & ~SCALER_DISPCTRL_DSP3_MUX_MASK) |
> > +				  VC4_SET_FIELD(mux, SCALER_DISPCTRL_DSP3_MUX));
> >   			break;
> >   
> >   		case 4:
> > -			dsp4_mux = vc4_state->assigned_channel;
> > +			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
> > +				mux = 3;
> > +			else
> > +				mux = vc4_state->assigned_channel;
> > +
> > +			reg = HVS_READ(SCALER_DISPEOLN);
> > +			HVS_WRITE(SCALER_DISPEOLN,
> > +				  (reg & ~SCALER_DISPEOLN_DSP4_MUX_MASK) |
> > +				  VC4_SET_FIELD(mux, SCALER_DISPEOLN_DSP4_MUX));
> > +
> >   			break;
> >   
> >   		case 5:
> > -			dsp5_mux = vc4_state->assigned_channel;
> > +			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
> > +				mux = 3;
> > +			else
> > +				mux = vc4_state->assigned_channel;
> > +
> > +			reg = HVS_READ(SCALER_DISPDITHER);
> > +			HVS_WRITE(SCALER_DISPDITHER,
> > +				  (reg & ~SCALER_DISPDITHER_DSP5_MUX_MASK) |
> > +				  VC4_SET_FIELD(mux, SCALER_DISPDITHER_DSP5_MUX));
> >   			break;
> >   
> >   		default:
> >   			break;
> >   		}
> >   	}
> > -
> > -	reg = HVS_READ(SCALER_DISPECTRL);
> > -	HVS_WRITE(SCALER_DISPECTRL,
> > -		  (reg & ~SCALER_DISPECTRL_DSP2_MUX_MASK) |
> > -		  VC4_SET_FIELD(dsp2_mux, SCALER_DISPECTRL_DSP2_MUX));
> > -
> > -	reg = HVS_READ(SCALER_DISPCTRL);
> > -	HVS_WRITE(SCALER_DISPCTRL,
> > -		  (reg & ~SCALER_DISPCTRL_DSP3_MUX_MASK) |
> > -		  VC4_SET_FIELD(dsp3_mux, SCALER_DISPCTRL_DSP3_MUX));
> > -
> > -	reg = HVS_READ(SCALER_DISPEOLN);
> > -	HVS_WRITE(SCALER_DISPEOLN,
> > -		  (reg & ~SCALER_DISPEOLN_DSP4_MUX_MASK) |
> > -		  VC4_SET_FIELD(dsp4_mux, SCALER_DISPEOLN_DSP4_MUX));
> > -
> > -	reg = HVS_READ(SCALER_DISPDITHER);
> > -	HVS_WRITE(SCALER_DISPDITHER,
> > -		  (reg & ~SCALER_DISPDITHER_DSP5_MUX_MASK) |
> > -		  VC4_SET_FIELD(dsp5_mux, SCALER_DISPDITHER_DSP5_MUX));
> >   }
> >   
> >   static void
> > @@ -769,21 +775,29 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
> >   		return -EINVAL;
> >   
> >   	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
> > +		struct vc4_crtc_state *old_vc4_crtc_state =
> > +			to_vc4_crtc_state(old_crtc_state);
> 
> In my opinion, the old_vc4_crtc_state definition is better to move to 
> patch6.
> Build error occurs in patch6 because old_vc4_crtc_state is used in patch6.

You're totally right, I've fixed it in my third version, thanks!
Maxime

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