diff mbox series

drm/bridge: dw-hdmi: disable SCDC configuration for invalid setups

Message ID 20190315095414.28520-1-narmstrong@baylibre.com (mailing list archive)
State New, archived
Headers show
Series drm/bridge: dw-hdmi: disable SCDC configuration for invalid setups | expand

Commit Message

Neil Armstrong March 15, 2019, 9:54 a.m. UTC
This patch is an attempt to limit HDMI 2.0 SCDC setup when :
- the SoC embeds an HDMI 1.4 only controller
- the EDID supports SCDC but not scrambling
- the EDID supports SCDC scrambling but not for low TMDS bit rates,
  while only supporting low TMDS bit rates

This to avoid communicating with the SCDC DDC slave uncessary, and
setting the DW-HDMI TMDS Scrambler setup when not supported by the
underlying hardware.

Reported-by: Rob Herring <robh@kernel.org>
Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---

Rob,

this patch should also solve your issue with your 11' display, could you
test it ?
If this works, I will focus on the underlying issue where the RK3399 SoC
freezes in your setup.

Thanks,
Neil

 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 34 ++++++++++++++++++++---
 1 file changed, 30 insertions(+), 4 deletions(-)

Comments

Rob Herring (Arm) March 15, 2019, 3:45 p.m. UTC | #1
On Fri, Mar 15, 2019 at 4:54 AM Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> This patch is an attempt to limit HDMI 2.0 SCDC setup when :
> - the SoC embeds an HDMI 1.4 only controller
> - the EDID supports SCDC but not scrambling
> - the EDID supports SCDC scrambling but not for low TMDS bit rates,
>   while only supporting low TMDS bit rates
>
> This to avoid communicating with the SCDC DDC slave uncessary, and
> setting the DW-HDMI TMDS Scrambler setup when not supported by the
> underlying hardware.
>
> Reported-by: Rob Herring <robh@kernel.org>
> Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support")
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>
> Rob,
>
> this patch should also solve your issue with your 11' display, could you
> test it ?

That works for me.

Tested-by: Rob Herring <robh@kernel.org>

Too answer your question on the other thread, there's not really any
model name for the panel I have. Probably what's in the EDID is the
best thing to go on.

Here's the panel on Amazon:

https://www.amazon.com/gp/product/B07GDDG3WJ/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

> If this works, I will focus on the underlying issue where the RK3399 SoC
> freezes in your setup.
>
> Thanks,
> Neil
>
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 34 ++++++++++++++++++++---
>  1 file changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index a63e5f0dae56..db761329a1e3 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -1037,6 +1037,31 @@ void dw_hdmi_phy_i2c_write(struct dw_hdmi *hdmi, unsigned short data,
>  }
>  EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
>
> +/* Filter out invalid setups to avoid configuring SCDC and scrambling */
> +static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi)
> +{
> +       struct drm_display_info *display = &hdmi->connector.display_info;
> +
> +       /* Completely disable SCDC support for older controllers */
> +       if (hdmi->version < 0x200a)
> +               return false;
> +
> +       /* Disable if SCDC is not supported, or if an HF-VSDB block is absent */
> +       if (!display->hdmi.scdc.supported ||
> +           !display->hdmi.scdc.scrambling.supported)
> +               return false;
> +
> +       /*
> +        * Disable if display only support low TMDS rates and scrambling
> +        * for low rates is not supported either
> +        */
> +       if (!display->hdmi.scdc.scrambling.low_rates &&
> +           display->max_tmds_clock <= 340000)
> +               return false;
> +
> +       return true;
> +}
> +
>  /*
>   * HDMI2.0 Specifies the following procedure for High TMDS Bit Rates:
>   * - The Source shall suspend transmission of the TMDS clock and data
> @@ -1055,7 +1080,7 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
>         unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
>
>         /* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
> -       if (hdmi->connector.display_info.hdmi.scdc.supported) {
> +       if (dw_hdmi_support_scdc(hdmi)) {
>                 if (mtmdsclock > HDMI14_MAX_TMDSCLK)
>                         drm_scdc_set_high_tmds_clock_ratio(hdmi->ddc, 1);
>                 else
> @@ -1579,8 +1604,9 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>
>         /* Set up HDMI_FC_INVIDCONF */
>         inv_val = (hdmi->hdmi_data.hdcp_enable ||
> -                  vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> -                  hdmi_info->scdc.scrambling.low_rates ?
> +                  (dw_hdmi_support_scdc(hdmi) &&
> +                   (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> +                    hdmi_info->scdc.scrambling.low_rates)) ?
>                 HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
>                 HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);
>
> @@ -1646,7 +1672,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>         }
>
>         /* Scrambling Control */
> -       if (hdmi_info->scdc.supported) {
> +       if (dw_hdmi_support_scdc(hdmi)) {
>                 if (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>                     hdmi_info->scdc.scrambling.low_rates) {
>                         /*
> --
> 2.20.1
>
Neil Armstrong March 25, 2019, 10:22 a.m. UTC | #2
Hi Andrzej, Laurent,

Gentle ping,
Did you have time to review this fix ?

Thanks !
Neil

On 15/03/2019 10:54, Neil Armstrong wrote:
> This patch is an attempt to limit HDMI 2.0 SCDC setup when :
> - the SoC embeds an HDMI 1.4 only controller
> - the EDID supports SCDC but not scrambling
> - the EDID supports SCDC scrambling but not for low TMDS bit rates,
>   while only supporting low TMDS bit rates
> 
> This to avoid communicating with the SCDC DDC slave uncessary, and
> setting the DW-HDMI TMDS Scrambler setup when not supported by the
> underlying hardware.
> 
> Reported-by: Rob Herring <robh@kernel.org>
> Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support")
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
> 
> Rob,
> 
> this patch should also solve your issue with your 11' display, could you
> test it ?
> If this works, I will focus on the underlying issue where the RK3399 SoC
> freezes in your setup.
> 
> Thanks,
> Neil
> 
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 34 ++++++++++++++++++++---
>  1 file changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index a63e5f0dae56..db761329a1e3 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -1037,6 +1037,31 @@ void dw_hdmi_phy_i2c_write(struct dw_hdmi *hdmi, unsigned short data,
>  }
>  EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
>  
> +/* Filter out invalid setups to avoid configuring SCDC and scrambling */
> +static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi)
> +{
> +	struct drm_display_info *display = &hdmi->connector.display_info;
> +
> +	/* Completely disable SCDC support for older controllers */
> +	if (hdmi->version < 0x200a)
> +		return false;
> +
> +	/* Disable if SCDC is not supported, or if an HF-VSDB block is absent */
> +	if (!display->hdmi.scdc.supported ||
> +	    !display->hdmi.scdc.scrambling.supported)
> +		return false;
> +
> +	/*
> +	 * Disable if display only support low TMDS rates and scrambling
> +	 * for low rates is not supported either
> +	 */
> +	if (!display->hdmi.scdc.scrambling.low_rates &&
> +	    display->max_tmds_clock <= 340000)
> +		return false;
> +
> +	return true;
> +}
> +
>  /*
>   * HDMI2.0 Specifies the following procedure for High TMDS Bit Rates:
>   * - The Source shall suspend transmission of the TMDS clock and data
> @@ -1055,7 +1080,7 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
>  	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
>  
>  	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
> -	if (hdmi->connector.display_info.hdmi.scdc.supported) {
> +	if (dw_hdmi_support_scdc(hdmi)) {
>  		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
>  			drm_scdc_set_high_tmds_clock_ratio(hdmi->ddc, 1);
>  		else
> @@ -1579,8 +1604,9 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>  
>  	/* Set up HDMI_FC_INVIDCONF */
>  	inv_val = (hdmi->hdmi_data.hdcp_enable ||
> -		   vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> -		   hdmi_info->scdc.scrambling.low_rates ?
> +		   (dw_hdmi_support_scdc(hdmi) &&
> +		    (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> +		     hdmi_info->scdc.scrambling.low_rates)) ?
>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);
>  
> @@ -1646,7 +1672,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>  	}
>  
>  	/* Scrambling Control */
> -	if (hdmi_info->scdc.supported) {
> +	if (dw_hdmi_support_scdc(hdmi)) {
>  		if (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>  		    hdmi_info->scdc.scrambling.low_rates) {
>  			/*
>
Andrzej Hajda March 25, 2019, 11:37 a.m. UTC | #3
On 15.03.2019 10:54, Neil Armstrong wrote:
> This patch is an attempt to limit HDMI 2.0 SCDC setup when :
> - the SoC embeds an HDMI 1.4 only controller
> - the EDID supports SCDC but not scrambling
> - the EDID supports SCDC scrambling but not for low TMDS bit rates,
>   while only supporting low TMDS bit rates
>
> This to avoid communicating with the SCDC DDC slave uncessary, and
> setting the DW-HDMI TMDS Scrambler setup when not supported by the
> underlying hardware.
>
> Reported-by: Rob Herring <robh@kernel.org>
> Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support")
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>
> Rob,
>
> this patch should also solve your issue with your 11' display, could you
> test it ?
> If this works, I will focus on the underlying issue where the RK3399 SoC
> freezes in your setup.
>
> Thanks,
> Neil
>
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 34 ++++++++++++++++++++---
>  1 file changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index a63e5f0dae56..db761329a1e3 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -1037,6 +1037,31 @@ void dw_hdmi_phy_i2c_write(struct dw_hdmi *hdmi, unsigned short data,
>  }
>  EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
>  
> +/* Filter out invalid setups to avoid configuring SCDC and scrambling */
> +static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi)
> +{
> +	struct drm_display_info *display = &hdmi->connector.display_info;
> +
> +	/* Completely disable SCDC support for older controllers */
> +	if (hdmi->version < 0x200a)
> +		return false;
> +
> +	/* Disable if SCDC is not supported, or if an HF-VSDB block is absent */
> +	if (!display->hdmi.scdc.supported ||
> +	    !display->hdmi.scdc.scrambling.supported)
> +		return false;
> +
> +	/*
> +	 * Disable if display only support low TMDS rates and scrambling
> +	 * for low rates is not supported either
> +	 */
> +	if (!display->hdmi.scdc.scrambling.low_rates &&
> +	    display->max_tmds_clock <= 340000)
> +		return false;
> +
> +	return true;
> +}
> +
>  /*
>   * HDMI2.0 Specifies the following procedure for High TMDS Bit Rates:
>   * - The Source shall suspend transmission of the TMDS clock and data
> @@ -1055,7 +1080,7 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
>  	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
>  
>  	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
> -	if (hdmi->connector.display_info.hdmi.scdc.supported) {
> +	if (dw_hdmi_support_scdc(hdmi)) {
>  		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
>  			drm_scdc_set_high_tmds_clock_ratio(hdmi->ddc, 1);
>  		else
> @@ -1579,8 +1604,9 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>  
>  	/* Set up HDMI_FC_INVIDCONF */
>  	inv_val = (hdmi->hdmi_data.hdcp_enable ||
> -		   vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> -		   hdmi_info->scdc.scrambling.low_rates ?
> +		   (dw_hdmi_support_scdc(hdmi) &&
> +		    (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
> +		     hdmi_info->scdc.scrambling.low_rates)) ?
>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);


The condition is hard to read, but I have no idea atm how make it
compact and pretty :)

Anyway:

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>


As I remember you can queue it to drm-misc, if not I can do it, just let
me know.


 --
Regards
Andrzej



>  
> @@ -1646,7 +1672,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>  	}
>  
>  	/* Scrambling Control */
> -	if (hdmi_info->scdc.supported) {
> +	if (dw_hdmi_support_scdc(hdmi)) {
>  		if (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>  		    hdmi_info->scdc.scrambling.low_rates) {
>  			/*
Neil Armstrong March 25, 2019, 12:12 p.m. UTC | #4
On 25/03/2019 12:37, Andrzej Hajda wrote:
> On 15.03.2019 10:54, Neil Armstrong wrote:
>> This patch is an attempt to limit HDMI 2.0 SCDC setup when :
>> - the SoC embeds an HDMI 1.4 only controller
>> - the EDID supports SCDC but not scrambling
>> - the EDID supports SCDC scrambling but not for low TMDS bit rates,
>>   while only supporting low TMDS bit rates
>>
>> This to avoid communicating with the SCDC DDC slave uncessary, and
>> setting the DW-HDMI TMDS Scrambler setup when not supported by the
>> underlying hardware.
>>
>> Reported-by: Rob Herring <robh@kernel.org>
>> Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support")
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>
>> Rob,
>>
>> this patch should also solve your issue with your 11' display, could you
>> test it ?
>> If this works, I will focus on the underlying issue where the RK3399 SoC
>> freezes in your setup.
>>
>> Thanks,
>> Neil
>>
>>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 34 ++++++++++++++++++++---
>>  1 file changed, 30 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> index a63e5f0dae56..db761329a1e3 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> @@ -1037,6 +1037,31 @@ void dw_hdmi_phy_i2c_write(struct dw_hdmi *hdmi, unsigned short data,
>>  }
>>  EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
>>  
>> +/* Filter out invalid setups to avoid configuring SCDC and scrambling */
>> +static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi)
>> +{
>> +	struct drm_display_info *display = &hdmi->connector.display_info;
>> +
>> +	/* Completely disable SCDC support for older controllers */
>> +	if (hdmi->version < 0x200a)
>> +		return false;
>> +
>> +	/* Disable if SCDC is not supported, or if an HF-VSDB block is absent */
>> +	if (!display->hdmi.scdc.supported ||
>> +	    !display->hdmi.scdc.scrambling.supported)
>> +		return false;
>> +
>> +	/*
>> +	 * Disable if display only support low TMDS rates and scrambling
>> +	 * for low rates is not supported either
>> +	 */
>> +	if (!display->hdmi.scdc.scrambling.low_rates &&
>> +	    display->max_tmds_clock <= 340000)
>> +		return false;
>> +
>> +	return true;
>> +}
>> +
>>  /*
>>   * HDMI2.0 Specifies the following procedure for High TMDS Bit Rates:
>>   * - The Source shall suspend transmission of the TMDS clock and data
>> @@ -1055,7 +1080,7 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
>>  	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
>>  
>>  	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
>> -	if (hdmi->connector.display_info.hdmi.scdc.supported) {
>> +	if (dw_hdmi_support_scdc(hdmi)) {
>>  		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
>>  			drm_scdc_set_high_tmds_clock_ratio(hdmi->ddc, 1);
>>  		else
>> @@ -1579,8 +1604,9 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>>  
>>  	/* Set up HDMI_FC_INVIDCONF */
>>  	inv_val = (hdmi->hdmi_data.hdcp_enable ||
>> -		   vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>> -		   hdmi_info->scdc.scrambling.low_rates ?
>> +		   (dw_hdmi_support_scdc(hdmi) &&
>> +		    (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>> +		     hdmi_info->scdc.scrambling.low_rates)) ?
>>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
>>  		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);
> 
> 
> The condition is hard to read, but I have no idea atm how make it
> compact and pretty :)

I made my best to make it barely readable...

We may need to reword this condition since on the DW-HMI in the Allwinner
H6, this is no more needed for scrambling !

> 
> Anyway:
> 
> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
> 
> 
> As I remember you can queue it to drm-misc, if not I can do it, just let
> me know.

I can and I'm queuing it right now, thanks for the review !

Neil

> 
> 
>  --
> Regards
> Andrzej
> 
> 
> 
>>  
>> @@ -1646,7 +1672,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>>  	}
>>  
>>  	/* Scrambling Control */
>> -	if (hdmi_info->scdc.supported) {
>> +	if (dw_hdmi_support_scdc(hdmi)) {
>>  		if (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
>>  		    hdmi_info->scdc.scrambling.low_rates) {
>>  			/*
> 
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index a63e5f0dae56..db761329a1e3 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -1037,6 +1037,31 @@  void dw_hdmi_phy_i2c_write(struct dw_hdmi *hdmi, unsigned short data,
 }
 EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
 
+/* Filter out invalid setups to avoid configuring SCDC and scrambling */
+static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi)
+{
+	struct drm_display_info *display = &hdmi->connector.display_info;
+
+	/* Completely disable SCDC support for older controllers */
+	if (hdmi->version < 0x200a)
+		return false;
+
+	/* Disable if SCDC is not supported, or if an HF-VSDB block is absent */
+	if (!display->hdmi.scdc.supported ||
+	    !display->hdmi.scdc.scrambling.supported)
+		return false;
+
+	/*
+	 * Disable if display only support low TMDS rates and scrambling
+	 * for low rates is not supported either
+	 */
+	if (!display->hdmi.scdc.scrambling.low_rates &&
+	    display->max_tmds_clock <= 340000)
+		return false;
+
+	return true;
+}
+
 /*
  * HDMI2.0 Specifies the following procedure for High TMDS Bit Rates:
  * - The Source shall suspend transmission of the TMDS clock and data
@@ -1055,7 +1080,7 @@  void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
 	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
 
 	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
-	if (hdmi->connector.display_info.hdmi.scdc.supported) {
+	if (dw_hdmi_support_scdc(hdmi)) {
 		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
 			drm_scdc_set_high_tmds_clock_ratio(hdmi->ddc, 1);
 		else
@@ -1579,8 +1604,9 @@  static void hdmi_av_composer(struct dw_hdmi *hdmi,
 
 	/* Set up HDMI_FC_INVIDCONF */
 	inv_val = (hdmi->hdmi_data.hdcp_enable ||
-		   vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
-		   hdmi_info->scdc.scrambling.low_rates ?
+		   (dw_hdmi_support_scdc(hdmi) &&
+		    (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
+		     hdmi_info->scdc.scrambling.low_rates)) ?
 		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
 		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);
 
@@ -1646,7 +1672,7 @@  static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	}
 
 	/* Scrambling Control */
-	if (hdmi_info->scdc.supported) {
+	if (dw_hdmi_support_scdc(hdmi)) {
 		if (vmode->mtmdsclock > HDMI14_MAX_TMDSCLK ||
 		    hdmi_info->scdc.scrambling.low_rates) {
 			/*