Re: [PATCH v7 2/2] drm/mediatek: Add isolation to edp

["LIANKUN YANG (杨连坤)" <Liankun.Yang@mediatek.com>]

On Wed, 2025-12-17 at 10:08 +0000, CK Hu (胡俊光) wrote:
> On Tue, 2025-11-04 at 16:55 +0800, Liankun Yang wrote:
> > Because edp doesn't expect any (un)plug events during runtime and
> > its process differs from DP. Therefore, it is necessary to isolate
> > the parsing capability, panel power, training state and enable
> > state.
> > 
> > And DP related behaviors are adjusted to execute in the second half
> > of the interrupt.
> > For DP details, see drm/mediatek: Adjust bandwidth limit for DP
> > 
> > Signed-off-by: Liankun Yang <liankun.yang@mediatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dp.c | 37 +++++++++++++++----------
> > ------
> >  1 file changed, 18 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> > b/drivers/gpu/drm/mediatek/mtk_dp.c
> > index 0ba2c208811c..efd4c45985ca 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> > @@ -2187,7 +2187,8 @@ static const struct drm_edid
> > *mtk_dp_edid_read(struct drm_bridge *bridge,
> >  	 * Parse capability here to let atomic_get_input_bus_fmts and
> >  	 * mode_valid use the capability to calculate sink bitrates.
> >  	 */
> > -	if (mtk_dp_parse_capabilities(mtk_dp)) {
> > +	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP &&
> > +	    mtk_dp_parse_capabilities(mtk_dp)) {
> 
> This is not related to dp training.
> If dp does not need to parse edid, describe WHY and do not mix edid
> modification with dp training modification.
> 

`mtk_dp_parse_capabilities` is related to DP training, it is
used in `mtk_dp_hpd_event_thread` before DP training, and then only
used by eDP when read edid.

Read edid continued according to its original logic and was unaffected.
	...
	drm_edid = drm_edid_read_ddc(connector, &mtk_dp->aux.ddc);

	/*
	 * Parse capability here to let atomic_get_input_bus_fmts and
	 * mode_valid use the capability to calculate sink bitrates.
	 */
	if (mtk_dp_parse_capabilities(mtk_dp)) {
		drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
		drm_edid_free(drm_edid);
		drm_edid = NULL;
	}

	if (drm_edid) {
	...

> >  		drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
> >  		drm_edid_free(drm_edid);
> >  		drm_edid = NULL;
> > @@ -2385,13 +2386,15 @@ static void
> > mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
> >  		return;
> >  	}
> >  
> > -	mtk_dp_aux_panel_poweron(mtk_dp, true);
> > +	if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP) {
> > +		mtk_dp_aux_panel_poweron(mtk_dp, true);
> >  
> > -	/* Training */
> > -	ret = mtk_dp_training(mtk_dp);
> > -	if (ret) {
> > -		drm_err(mtk_dp->drm_dev, "Training failed, %d\n", ret);
> > -		goto power_off_aux;
> > +		/* Training */
> > +		ret = mtk_dp_training(mtk_dp);
> > +		if (ret) {
> > +			drm_err(mtk_dp->drm_dev, "Training failed,
> > %d\n", ret);
> > +			goto power_off_aux;
> > +		}
> 
> Merge this to previous patch.
> 
> >  	}
> >  
> >  	ret = mtk_dp_video_config(mtk_dp);
> > @@ -2411,7 +2414,9 @@ static void
> > mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
> >  		       sizeof(mtk_dp->info.audio_cur_cfg));
> >  	}
> >  
> > -	mtk_dp->enabled = true;
> > +	if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP)
> > +		mtk_dp->enabled = true;
> 
> Merge this to previous patch.
> 
> > +
> >  	mtk_dp_update_plugged_status(mtk_dp);
> >  
> >  	return;
> > @@ -2426,21 +2431,15 @@ static void
> > mtk_dp_bridge_atomic_disable(struct drm_bridge *bridge,
> >  {
> >  	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
> >  
> > -	mtk_dp->enabled = false;
> > +	if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP) {
> > +		mtk_dp->enabled = false;
> 
> Merge this to previous patch.
> 
> > +		mtk_dp_aux_panel_poweron(mtk_dp, false);
> 
> You change the code flow of DRM_MODE_CONNECTOR_eDP.
> I think you should not change this.
> 
> > +	}
> > +
> >  	mtk_dp_update_plugged_status(mtk_dp);
> >  	mtk_dp_video_enable(mtk_dp, false);
> >  	mtk_dp_audio_mute(mtk_dp, true);
> >  
> > -	if (mtk_dp->train_info.cable_plugged_in) {
> > -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> > DP_SET_POWER_D3);
> > -		usleep_range(2000, 3000);
> 
> For DRM_MODE_CONNECTOR_DP, you remove this usleep. This may cause
> side effect.
> Doesn't it?
> 

The modification to `mtk_dp_bridge_atomic_disable` here is base on
the same logic as `mtk_dp_aux_panel_poweron(mtk_dp, false);`.

Modify part of in `mtk_dp_bridge_atomic_disable`
  if (mtk_dp->train_info.cable_plugged_in) {
    drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
    usleep_range(2000, 3000);
  }

  /* power off aux */
  mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
		DP_PWR_STATE_BANDGAP_TPLL,
		DP_PWR_STATE_MASK);

Modify part of in `mtk_dp_aux_panel_poweron(mtk_dp, false);`
  if (pwron) {
    ....
  } else {
    /* power off panel */
    drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
    usleep_range(2000, 3000);

    /* power off aux */
    mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
			DP_PWR_STATE_BANDGAP_TPLL,
			DP_PWR_STATE_MASK);
  }

The `mtk_dp_aux_panel_poweron` function fails to align.
Within the `mtk_dp_hpd_event_thread`, if DP is disconnected,
the `mtk_dp_aux_panel_poweron` function will write from `aux`
to `DPRX`, causing a failure and thus preventing symmetry.

> > -	}
> > -
> > -	/* power off aux */
> > -	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> > -			   DP_PWR_STATE_BANDGAP_TPLL,
> > -			   DP_PWR_STATE_MASK);
> 
> if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP) {
> 	/* power off aux */
> 	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> 			   DP_PWR_STATE_BANDGAP_TPLL,
> 			   DP_PWR_STATE_MASK);
> }
> 
> Regards,
> CK
> 
> > -
> >  	/* SDP path reset sw*/
> >  	mtk_dp_sdp_path_reset(mtk_dp);
> >  
> 
>