From: Jayesh Choudhary <j-choudhary@ti.com>

Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
this bridge or not. In the legacy usecase with
!DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
we need to have mode_valid() in drm_bridge_funcs.

Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index f3076e9cdabbe..7178a01e4d4d8 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2162,6 +2162,25 @@ static const struct drm_edid *cdns_mhdp_bridge_edid_read(struct drm_bridge *brid
 	return cdns_mhdp_edid_read(mhdp, connector);
 }
 
+static enum drm_mode_status
+cdns_mhdp_bridge_mode_valid(struct drm_bridge *bridge,
+			    const struct drm_display_info *info,
+			    const struct drm_display_mode *mode)
+{
+	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
+
+	mutex_lock(&mhdp->link_mutex);
+
+	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
+				    mhdp->link.rate)) {
+		mutex_unlock(&mhdp->link_mutex);
+		return MODE_CLOCK_HIGH;
+	}
+
+	mutex_unlock(&mhdp->link_mutex);
+	return MODE_OK;
+}
+
 static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.atomic_enable = cdns_mhdp_atomic_enable,
 	.atomic_disable = cdns_mhdp_atomic_disable,
@@ -2176,6 +2195,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.edid_read = cdns_mhdp_bridge_edid_read,
 	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
 	.hpd_disable = cdns_mhdp_bridge_hpd_disable,
+	.mode_valid = cdns_mhdp_bridge_mode_valid,
 };
 
 static bool cdns_mhdp_detect_hpd(struct cdns_mhdp_device *mhdp, bool *hpd_pulse)
-- 
2.34.1

Hi,

On 20/11/2025 14:14, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
> 
> Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
> this bridge or not. In the legacy usecase with
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
> drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
> we need to have mode_valid() in drm_bridge_funcs.

This looks fine, but a fix should always explain what the issue is. What
is the behavior without this patch, if DRM_BRIDGE_ATTACH_NO_CONNECTOR is
set?

 Tomi

> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
> ---
>  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 20 +++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index f3076e9cdabbe..7178a01e4d4d8 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2162,6 +2162,25 @@ static const struct drm_edid *cdns_mhdp_bridge_edid_read(struct drm_bridge *brid
>  	return cdns_mhdp_edid_read(mhdp, connector);
>  }
>  
> +static enum drm_mode_status
> +cdns_mhdp_bridge_mode_valid(struct drm_bridge *bridge,
> +			    const struct drm_display_info *info,
> +			    const struct drm_display_mode *mode)
> +{
> +	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> +
> +	mutex_lock(&mhdp->link_mutex);
> +
> +	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
> +				    mhdp->link.rate)) {
> +		mutex_unlock(&mhdp->link_mutex);
> +		return MODE_CLOCK_HIGH;
> +	}
> +
> +	mutex_unlock(&mhdp->link_mutex);
> +	return MODE_OK;
> +}
> +
>  static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
>  	.atomic_enable = cdns_mhdp_atomic_enable,
>  	.atomic_disable = cdns_mhdp_atomic_disable,
> @@ -2176,6 +2195,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
>  	.edid_read = cdns_mhdp_bridge_edid_read,
>  	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
>  	.hpd_disable = cdns_mhdp_bridge_hpd_disable,
> +	.mode_valid = cdns_mhdp_bridge_mode_valid,
>  };
>  
>  static bool cdns_mhdp_detect_hpd(struct cdns_mhdp_device *mhdp, bool *hpd_pulse)

On 21/11/25 18:13, Tomi Valkeinen wrote:
> Hi,
> 
> On 20/11/2025 14:14, Harikrishna Shenoy wrote:
>> From: Jayesh Choudhary <j-choudhary@ti.com>
>>
>> Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
>> this bridge or not. In the legacy usecase with
>> !DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
>> drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
>> we need to have mode_valid() in drm_bridge_funcs.
> 
> This looks fine, but a fix should always explain what the issue is. What
> is the behavior without this patch, if DRM_BRIDGE_ATTACH_NO_CONNECTOR is
> set?
> 
>   Tomi
Hi Tomi,

Without this patch some modes which should get rejected based on 
bandwidth requirement will not be rejected as mode check/validation will 
not hit 'cdns_mhdp_bandwidth_ok'as with DRM_BRIDGE_ATTACH_NO_CONNECTOR 
flag set we use hooks from drm_bridge_funcs.

will include this in commit message.

Regards,
Hari

> 
>> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
>> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
>> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
>> ---
>>   .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 20 +++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> index f3076e9cdabbe..7178a01e4d4d8 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> @@ -2162,6 +2162,25 @@ static const struct drm_edid *cdns_mhdp_bridge_edid_read(struct drm_bridge *brid
>>   	return cdns_mhdp_edid_read(mhdp, connector);
>>   }
>>   
>> +static enum drm_mode_status
>> +cdns_mhdp_bridge_mode_valid(struct drm_bridge *bridge,
>> +			    const struct drm_display_info *info,
>> +			    const struct drm_display_mode *mode)
>> +{
>> +	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
>> +
>> +	mutex_lock(&mhdp->link_mutex);
>> +
>> +	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
>> +				    mhdp->link.rate)) {
>> +		mutex_unlock(&mhdp->link_mutex);
>> +		return MODE_CLOCK_HIGH;
>> +	}
>> +
>> +	mutex_unlock(&mhdp->link_mutex);
>> +	return MODE_OK;
>> +}
>> +
>>   static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
>>   	.atomic_enable = cdns_mhdp_atomic_enable,
>>   	.atomic_disable = cdns_mhdp_atomic_disable,
>> @@ -2176,6 +2195,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
>>   	.edid_read = cdns_mhdp_bridge_edid_read,
>>   	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
>>   	.hpd_disable = cdns_mhdp_bridge_hpd_disable,
>> +	.mode_valid = cdns_mhdp_bridge_mode_valid,
>>   };
>>   
>>   static bool cdns_mhdp_detect_hpd(struct cdns_mhdp_device *mhdp, bool *hpd_pulse)
>