[PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[Lyude Paul]

When doing a modeset where the sink is transitioning from D3 to D0 , it
would sometimes be possible for the initial power_up_phy() to start
timing out. This would only be observed in the last action before the
sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
originally thought this might be an issue with us accidentally shutting
off the aux block when putting the sink into D3, but since the DP spec
mandates that sinks must wake up within 1ms while we have 100ms to
respond to an ESI irq, this didn't really add up. Turns out that the
problem is more subtle then that:

It turns out that the timeout is from us not enabling DPMS on the MST
hub before actually trying to initiate sideband communications. This
would cause the first sideband communication (power_up_phy()), to start
timing out because the sink wasn't ready to respond. Afterwards, we
would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
intel_ddi_pre_enable_dp(), which would actually result in waking up the
sink so that sideband requests would work again.

Since DPMS is what lets us actually bring the hub up into a state where
sideband communications become functional again, we just need to make
sure to enable DPMS on the display before attempting to perform sideband
communications.

Changes since v1:
- Remove comment above if (!intel_dp->is_mst) - vsryjala
- Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
  keep enable/disable paths symmetrical
- Improve commit message - dhnkrn
Changes since v2:
- Only send DPMS off when we're disabling the last sink, and only send
  DPMS on when we're enabling the first sink - dhnkrn
Changes since v3:
- Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: stable@vger.kernel.org
Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.")
---
 drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
 drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index a6672a9abd85..92cb26b18a9b 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
 
 	intel_ddi_init_dp_buf_reg(encoder);
-	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+	if (!is_mst)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
 	intel_dp_start_link_train(intel_dp);
 	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
 		intel_dp_stop_link_train(intel_dp);
@@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
 	struct intel_dp *intel_dp = &dig_port->dp;
+	bool is_mst = intel_crtc_has_type(old_crtc_state,
+					  INTEL_OUTPUT_DP_MST);
 
 	/*
 	 * Power down sink before disabling the port, otherwise we end
 	 * up getting interrupts from the sink on detecting link loss.
 	 */
-	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+	if (!is_mst)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 
 	intel_disable_ddi_buf(encoder);
 
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index c3de0918ee13..9e6956c08688 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 	intel_dp->active_mst_links--;
 
 	intel_mst->connector = NULL;
-	if (intel_dp->active_mst_links == 0)
+	if (intel_dp->active_mst_links == 0) {
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 		intel_dig_port->base.post_disable(&intel_dig_port->base,
 						  old_crtc_state, NULL);
+	}
 
 	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
 }
@@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 
 	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
 
+	if (intel_dp->active_mst_links == 0)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+
 	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
+
 	if (intel_dp->active_mst_links == 0)
 		intel_dig_port->base.pre_enable(&intel_dig_port->base,
 						pipe_config, NULL);
-- 
2.14.3

Re: [PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[Ville Syrjälä]

On Fri, Apr 06, 2018 at 12:28:30PM -0700, Dhinakaran Pandiyan wrote:
> 
> 
> 
> On Fri, 2018-04-06 at 14:52 -0400, Lyude Paul wrote:
> > When doing a modeset where the sink is transitioning from D3 to D0 , it
> > would sometimes be possible for the initial power_up_phy() to start
> > timing out. This would only be observed in the last action before the
> > sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
> > originally thought this might be an issue with us accidentally shutting
> > off the aux block when putting the sink into D3, but since the DP spec
> > mandates that sinks must wake up within 1ms while we have 100ms to
> > respond to an ESI irq, this didn't really add up. Turns out that the
> > problem is more subtle then that:
> > 
> > It turns out that the timeout is from us not enabling DPMS on the MST
> > hub before actually trying to initiate sideband communications. This
> > would cause the first sideband communication (power_up_phy()), to start
> > timing out because the sink wasn't ready to respond. Afterwards, we
> > would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
> > intel_ddi_pre_enable_dp(), which would actually result in waking up the
> > sink so that sideband requests would work again.
> > 
> > Since DPMS is what lets us actually bring the hub up into a state where
> > sideband communications become functional again, we just need to make
> > sure to enable DPMS on the display before attempting to perform sideband
> > communications.
> > 
> 
> Matches my understanding of the problem
> 
> Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> 
> It's better to get an ack from Ville considering I was okay with the
> D3_AUX_ON solution too.

lgtm
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> 
> > Changes since v1:
> > - Remove comment above if (!intel_dp->is_mst) - vsryjala
> > - Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
> >   keep enable/disable paths symmetrical
> > - Improve commit message - dhnkrn
> > Changes since v2:
> > - Only send DPMS off when we're disabling the last sink, and only send
> >   DPMS on when we're enabling the first sink - dhnkrn
> > Changes since v3:
> > - Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala
> > 
> > Signed-off-by: Lyude Paul <lyude@redhat.com>
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Laura Abbott <labbott@redhat.com>
> > Cc: stable@vger.kernel.org
> > Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.")
> > ---
> >  drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
> >  drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
> >  2 files changed, 13 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index a6672a9abd85..92cb26b18a9b 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> >  		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
> >  
> >  	intel_ddi_init_dp_buf_reg(encoder);
> > -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > +	if (!is_mst)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> >  	intel_dp_start_link_train(intel_dp);
> >  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
> >  		intel_dp_stop_link_train(intel_dp);
> > @@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
> >  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> >  	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
> >  	struct intel_dp *intel_dp = &dig_port->dp;
> > +	bool is_mst = intel_crtc_has_type(old_crtc_state,
> > +					  INTEL_OUTPUT_DP_MST);
> >  
> >  	/*
> >  	 * Power down sink before disabling the port, otherwise we end
> >  	 * up getting interrupts from the sink on detecting link loss.
> >  	 */
> > -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > +	if (!is_mst)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> >  
> >  	intel_disable_ddi_buf(encoder);
> >  
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index c3de0918ee13..9e6956c08688 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
> >  	intel_dp->active_mst_links--;
> >  
> >  	intel_mst->connector = NULL;
> > -	if (intel_dp->active_mst_links == 0)
> > +	if (intel_dp->active_mst_links == 0) {
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> >  		intel_dig_port->base.post_disable(&intel_dig_port->base,
> >  						  old_crtc_state, NULL);
> > +	}
> >  
> >  	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
> >  }
> > @@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
> >  
> >  	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
> >  
> > +	if (intel_dp->active_mst_links == 0)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > +
> >  	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
> > +
> >  	if (intel_dp->active_mst_links == 0)
> >  		intel_dig_port->base.pre_enable(&intel_dig_port->base,
> >  						pipe_config, NULL);

-- 
Ville Syrjälä
Intel OTC

Re: [PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[Dhinakaran Pandiyan]

On Fri, 2018-04-06 at 14:52 -0400, Lyude Paul wrote:
> When doing a modeset where the sink is transitioning from D3 to D0 , it
> would sometimes be possible for the initial power_up_phy() to start
> timing out. This would only be observed in the last action before the
> sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
> originally thought this might be an issue with us accidentally shutting
> off the aux block when putting the sink into D3, but since the DP spec
> mandates that sinks must wake up within 1ms while we have 100ms to
> respond to an ESI irq, this didn't really add up. Turns out that the
> problem is more subtle then that:
> 
> It turns out that the timeout is from us not enabling DPMS on the MST
> hub before actually trying to initiate sideband communications. This
> would cause the first sideband communication (power_up_phy()), to start
> timing out because the sink wasn't ready to respond. Afterwards, we
> would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
> intel_ddi_pre_enable_dp(), which would actually result in waking up the
> sink so that sideband requests would work again.
> 
> Since DPMS is what lets us actually bring the hub up into a state where
> sideband communications become functional again, we just need to make
> sure to enable DPMS on the display before attempting to perform sideband
> communications.
> 

Matches my understanding of the problem

Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>

It's better to get an ack from Ville considering I was okay with the
D3_AUX_ON solution too.


> Changes since v1:
> - Remove comment above if (!intel_dp->is_mst) - vsryjala
> - Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
>   keep enable/disable paths symmetrical
> - Improve commit message - dhnkrn
> Changes since v2:
> - Only send DPMS off when we're disabling the last sink, and only send
>   DPMS on when we're enabling the first sink - dhnkrn
> Changes since v3:
> - Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: stable@vger.kernel.org
> Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.")
> ---
>  drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
>  drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
>  2 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index a6672a9abd85..92cb26b18a9b 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
>  		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
>  
>  	intel_ddi_init_dp_buf_reg(encoder);
> -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +	if (!is_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
>  	intel_dp_start_link_train(intel_dp);
>  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
>  		intel_dp_stop_link_train(intel_dp);
> @@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
>  	struct intel_dp *intel_dp = &dig_port->dp;
> +	bool is_mst = intel_crtc_has_type(old_crtc_state,
> +					  INTEL_OUTPUT_DP_MST);
>  
>  	/*
>  	 * Power down sink before disabling the port, otherwise we end
>  	 * up getting interrupts from the sink on detecting link loss.
>  	 */
> -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> +	if (!is_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>  
>  	intel_disable_ddi_buf(encoder);
>  
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> index c3de0918ee13..9e6956c08688 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
>  	intel_dp->active_mst_links--;
>  
>  	intel_mst->connector = NULL;
> -	if (intel_dp->active_mst_links == 0)
> +	if (intel_dp->active_mst_links == 0) {
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>  		intel_dig_port->base.post_disable(&intel_dig_port->base,
>  						  old_crtc_state, NULL);
> +	}
>  
>  	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
>  }
> @@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
>  
>  	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
>  
> +	if (intel_dp->active_mst_links == 0)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +
>  	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
> +
>  	if (intel_dp->active_mst_links == 0)
>  		intel_dig_port->base.pre_enable(&intel_dig_port->base,
>  						pipe_config, NULL);

Re: [PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[Laura Abbott]

On 04/06/2018 11:52 AM, Lyude Paul wrote:
> When doing a modeset where the sink is transitioning from D3 to D0 , it
> would sometimes be possible for the initial power_up_phy() to start
> timing out. This would only be observed in the last action before the
> sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
> originally thought this might be an issue with us accidentally shutting
> off the aux block when putting the sink into D3, but since the DP spec
> mandates that sinks must wake up within 1ms while we have 100ms to
> respond to an ESI irq, this didn't really add up. Turns out that the
> problem is more subtle then that:
> 
> It turns out that the timeout is from us not enabling DPMS on the MST
> hub before actually trying to initiate sideband communications. This
> would cause the first sideband communication (power_up_phy()), to start
> timing out because the sink wasn't ready to respond. Afterwards, we
> would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
> intel_ddi_pre_enable_dp(), which would actually result in waking up the
> sink so that sideband requests would work again.
> 
> Since DPMS is what lets us actually bring the hub up into a state where
> sideband communications become functional again, we just need to make
> sure to enable DPMS on the display before attempting to perform sideband
> communications.
> 
> Changes since v1:
> - Remove comment above if (!intel_dp->is_mst) - vsryjala
> - Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
>    keep enable/disable paths symmetrical
> - Improve commit message - dhnkrn
> Changes since v2:
> - Only send DPMS off when we're disabling the last sink, and only send
>    DPMS on when we're enabling the first sink - dhnkrn
> Changes since v3:
> - Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala
> 

For the booting docked with lid down case:

Tested-by: Laura Abbott <labbott@redhat.com>

> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: stable@vger.kernel.org
> Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.")
> ---
>   drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
>   drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
>   2 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index a6672a9abd85..92cb26b18a9b 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
>   		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
>   
>   	intel_ddi_init_dp_buf_reg(encoder);
> -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +	if (!is_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
>   	intel_dp_start_link_train(intel_dp);
>   	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
>   		intel_dp_stop_link_train(intel_dp);
> @@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
>   	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>   	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
>   	struct intel_dp *intel_dp = &dig_port->dp;
> +	bool is_mst = intel_crtc_has_type(old_crtc_state,
> +					  INTEL_OUTPUT_DP_MST);
>   
>   	/*
>   	 * Power down sink before disabling the port, otherwise we end
>   	 * up getting interrupts from the sink on detecting link loss.
>   	 */
> -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> +	if (!is_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>   
>   	intel_disable_ddi_buf(encoder);
>   
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> index c3de0918ee13..9e6956c08688 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
>   	intel_dp->active_mst_links--;
>   
>   	intel_mst->connector = NULL;
> -	if (intel_dp->active_mst_links == 0)
> +	if (intel_dp->active_mst_links == 0) {
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>   		intel_dig_port->base.post_disable(&intel_dig_port->base,
>   						  old_crtc_state, NULL);
> +	}
>   
>   	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
>   }
> @@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
>   
>   	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
>   
> +	if (intel_dp->active_mst_links == 0)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +
>   	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
> +
>   	if (intel_dp->active_mst_links == 0)
>   		intel_dig_port->base.pre_enable(&intel_dig_port->base,
>   						pipe_config, NULL);
> 

Re: [PATCH v4] drm/i915/dp: Send DPCD ON for MST before phy_up

[Lyude Paul]

On Fri, 2018-04-06 at 12:48 -0700, Laura Abbott wrote:
> On 04/06/2018 11:52 AM, Lyude Paul wrote:
> > When doing a modeset where the sink is transitioning from D3 to D0 , it
> > would sometimes be possible for the initial power_up_phy() to start
> > timing out. This would only be observed in the last action before the
> > sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
> > originally thought this might be an issue with us accidentally shutting
> > off the aux block when putting the sink into D3, but since the DP spec
> > mandates that sinks must wake up within 1ms while we have 100ms to
> > respond to an ESI irq, this didn't really add up. Turns out that the
> > problem is more subtle then that:
> > 
> > It turns out that the timeout is from us not enabling DPMS on the MST
> > hub before actually trying to initiate sideband communications. This
> > would cause the first sideband communication (power_up_phy()), to start
> > timing out because the sink wasn't ready to respond. Afterwards, we
> > would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
> > intel_ddi_pre_enable_dp(), which would actually result in waking up the
> > sink so that sideband requests would work again.
> > 
> > Since DPMS is what lets us actually bring the hub up into a state where
> > sideband communications become functional again, we just need to make
> > sure to enable DPMS on the display before attempting to perform sideband
> > communications.
> > 
> > Changes since v1:
> > - Remove comment above if (!intel_dp->is_mst) - vsryjala
> > - Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
> >    keep enable/disable paths symmetrical
> > - Improve commit message - dhnkrn
> > Changes since v2:
> > - Only send DPMS off when we're disabling the last sink, and only send
> >    DPMS on when we're enabling the first sink - dhnkrn
> > Changes since v3:
> > - Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala
> > 
> 
> For the booting docked with lid down case:
> 
> Tested-by: Laura Abbott <labbott@redhat.com>

Awesome, will push once the CI run finishes. Thanks for the help!
> 
> > Signed-off-by: Lyude Paul <lyude@redhat.com>
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Laura Abbott <labbott@redhat.com>
> > Cc: stable@vger.kernel.org
> > Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST
> > hub.")
> > ---
> >   drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
> >   drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
> >   2 files changed, 13 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> > b/drivers/gpu/drm/i915/intel_ddi.c
> > index a6672a9abd85..92cb26b18a9b 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct
> > intel_encoder *encoder,
> >   		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
> >   
> >   	intel_ddi_init_dp_buf_reg(encoder);
> > -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > +	if (!is_mst)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> >   	intel_dp_start_link_train(intel_dp);
> >   	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
> >   		intel_dp_stop_link_train(intel_dp);
> > @@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct
> > intel_encoder *encoder,
> >   	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> >   	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder-
> > >base);
> >   	struct intel_dp *intel_dp = &dig_port->dp;
> > +	bool is_mst = intel_crtc_has_type(old_crtc_state,
> > +					  INTEL_OUTPUT_DP_MST);
> >   
> >   	/*
> >   	 * Power down sink before disabling the port, otherwise we end
> >   	 * up getting interrupts from the sink on detecting link loss.
> >   	 */
> > -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > +	if (!is_mst)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> >   
> >   	intel_disable_ddi_buf(encoder);
> >   
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index c3de0918ee13..9e6956c08688 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct
> > intel_encoder *encoder,
> >   	intel_dp->active_mst_links--;
> >   
> >   	intel_mst->connector = NULL;
> > -	if (intel_dp->active_mst_links == 0)
> > +	if (intel_dp->active_mst_links == 0) {
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> >   		intel_dig_port->base.post_disable(&intel_dig_port->base,
> >   						  old_crtc_state, NULL);
> > +	}
> >   
> >   	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
> >   }
> > @@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct
> > intel_encoder *encoder,
> >   
> >   	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
> >   
> > +	if (intel_dp->active_mst_links == 0)
> > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > +
> >   	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector-
> > >port, true);
> > +
> >   	if (intel_dp->active_mst_links == 0)
> >   		intel_dig_port->base.pre_enable(&intel_dig_port->base,
> >   						pipe_config, NULL);
> > 
> 
> 
-- 
Cheers,
	Lyude Paul

[PATCH v5] drm/i915/dp: Send DPCD ON for MST before phy_up

[Lyude Paul]

When doing a modeset where the sink is transitioning from D3 to D0 , it
would sometimes be possible for the initial power_up_phy() to start
timing out. This would only be observed in the last action before the
sink went into D3 mode was intel_dp_sink_dpms(DRM_MODE_DPMS_OFF). We
originally thought this might be an issue with us accidentally shutting
off the aux block when putting the sink into D3, but since the DP spec
mandates that sinks must wake up within 1ms while we have 100ms to
respond to an ESI irq, this didn't really add up. Turns out that the
problem is more subtle then that:

It turns out that the timeout is from us not enabling DPMS on the MST
hub before actually trying to initiate sideband communications. This
would cause the first sideband communication (power_up_phy()), to start
timing out because the sink wasn't ready to respond. Afterwards, we
would call intel_dp_sink_dpms(DRM_MODE_DPMS_ON) in
intel_ddi_pre_enable_dp(), which would actually result in waking up the
sink so that sideband requests would work again.

Since DPMS is what lets us actually bring the hub up into a state where
sideband communications become functional again, we just need to make
sure to enable DPMS on the display before attempting to perform sideband
communications.

Changes since v1:
- Remove comment above if (!intel_dp->is_mst) - vsryjala
- Move intel_dp_sink_dpms() for MST into intel_dp_post_disable_mst() to
  keep enable/disable paths symmetrical
- Improve commit message - dhnkrn
Changes since v2:
- Only send DPMS off when we're disabling the last sink, and only send
  DPMS on when we're enabling the first sink - dhnkrn
Changes since v3:
- Check against is_mst, not intel_dp->is_mst - dhnkrn/vsyrjala

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: stable@vger.kernel.org
Fixes: ad260ab32a4d9 ("drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.")
---
No actual changes other than t-b and r-bs. Resending because I don't
have access to the "test latest revision again" button and I'm very much
sure these CI results are bogus.

 drivers/gpu/drm/i915/intel_ddi.c    | 8 ++++++--
 drivers/gpu/drm/i915/intel_dp_mst.c | 8 +++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index a6672a9abd85..92cb26b18a9b 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2324,7 +2324,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 		intel_prepare_dp_ddi_buffers(encoder, crtc_state);
 
 	intel_ddi_init_dp_buf_reg(encoder);
-	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+	if (!is_mst)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
 	intel_dp_start_link_train(intel_dp);
 	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
 		intel_dp_stop_link_train(intel_dp);
@@ -2422,12 +2423,15 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
 	struct intel_dp *intel_dp = &dig_port->dp;
+	bool is_mst = intel_crtc_has_type(old_crtc_state,
+					  INTEL_OUTPUT_DP_MST);
 
 	/*
 	 * Power down sink before disabling the port, otherwise we end
 	 * up getting interrupts from the sink on detecting link loss.
 	 */
-	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+	if (!is_mst)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 
 	intel_disable_ddi_buf(encoder);
 
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index c3de0918ee13..9e6956c08688 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -180,9 +180,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 	intel_dp->active_mst_links--;
 
 	intel_mst->connector = NULL;
-	if (intel_dp->active_mst_links == 0)
+	if (intel_dp->active_mst_links == 0) {
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 		intel_dig_port->base.post_disable(&intel_dig_port->base,
 						  old_crtc_state, NULL);
+	}
 
 	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
 }
@@ -223,7 +225,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 
 	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
 
+	if (intel_dp->active_mst_links == 0)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+
 	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
+
 	if (intel_dp->active_mst_links == 0)
 		intel_dig_port->base.pre_enable(&intel_dig_port->base,
 						pipe_config, NULL);
-- 
2.14.3