[v2] Apply drm_bridge_connector helper for the Analogix DP driver

[PATCH v2 07/12] drm/bridge: analogix_dp: Add support to find panel or bridge

Posted by Damon Ding 3 months ago

Since the panel/bridge should logically be positioned behind the
Analogix bridge in the display pipeline, it makes sense to handle
the panel/bridge parsing on the Analogix side.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
---
 .../drm/bridge/analogix/analogix_dp_core.c    | 48 +++++++++++++++++++
 include/drm/bridge/analogix_dp.h              |  2 +
 2 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 78d68310e4f6..660f95e90490 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -19,12 +19,14 @@
 #include <linux/platform_device.h>
 
 #include <drm/bridge/analogix_dp.h>
+#include <drm/display/drm_dp_aux_bus.h>
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
@@ -1707,6 +1709,52 @@ struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp)
 }
 EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
 
+static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
+{
+	struct analogix_dp_device *dp = to_dp(aux);
+	struct analogix_dp_plat_data *plat_data = dp->plat_data;
+	int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
+	int ret;
+
+	/*
+	 * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no valid panel
+	 * or bridge nodes. The driver should go on for the driver-free bridge or the DP
+	 * mode applications.
+	 */
+	ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
+					  &plat_data->panel, &plat_data->bridge);
+	if (ret && ret != -ENODEV)
+		return ret;
+
+	return component_add(dp->dev, plat_data->ops);
+}
+
+int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp)
+{
+	int ret;
+
+	ret = devm_of_dp_aux_populate_bus(&dp->aux, analogix_dp_aux_done_probing);
+	if (ret) {
+		/*
+		 * If devm_of_dp_aux_populate_bus() returns -ENODEV, the done_probing() will
+		 * not be called because there are no EP devices. Then the callback function
+		 * analogix_dp_aux_done_probing() will be called directly in order to support
+		 * the other valid DT configurations.
+		 *
+		 * NOTE: The devm_of_dp_aux_populate_bus() is allowed to return -EPROBE_DEFER.
+		 */
+		if (ret != -ENODEV) {
+			dev_err(dp->dev, "failed to populate aux bus\n");
+			return ret;
+		}
+
+		return analogix_dp_aux_done_probing(&dp->aux);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(analogix_dp_find_panel_or_bridge);
+
 MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
 MODULE_DESCRIPTION("Analogix DP Core Driver");
 MODULE_LICENSE("GPL v2");
diff --git a/include/drm/bridge/analogix_dp.h b/include/drm/bridge/analogix_dp.h
index 202e5eafb2cc..0b6d85f1924e 100644
--- a/include/drm/bridge/analogix_dp.h
+++ b/include/drm/bridge/analogix_dp.h
@@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
 	struct drm_bridge *bridge;
 	struct drm_encoder *encoder;
 	struct drm_connector *connector;
+	const struct component_ops *ops;
 
 	int (*power_on)(struct analogix_dp_plat_data *);
 	int (*power_off)(struct analogix_dp_plat_data *);
@@ -52,5 +53,6 @@ int analogix_dp_stop_crc(struct drm_connector *connector);
 
 struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct drm_dp_aux *aux);
 struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
+int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp);
 
 #endif /* _ANALOGIX_DP_H_ */
-- 
2.34.1

Re: [PATCH v2 07/12] drm/bridge: analogix_dp: Add support to find panel or bridge

Posted by Heiko Stübner 2 months, 4 weeks ago

Hi Damon,

Am Mittwoch, 9. Juli 2025, 09:01:34 Mitteleuropäische Sommerzeit schrieb Damon Ding:
> Since the panel/bridge should logically be positioned behind the
> Analogix bridge in the display pipeline, it makes sense to handle
> the panel/bridge parsing on the Analogix side.
> 
> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
> ---
>  .../drm/bridge/analogix/analogix_dp_core.c    | 48 +++++++++++++++++++
>  include/drm/bridge/analogix_dp.h              |  2 +
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 78d68310e4f6..660f95e90490 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -19,12 +19,14 @@
>  #include <linux/platform_device.h>
>  
>  #include <drm/bridge/analogix_dp.h>
> +#include <drm/display/drm_dp_aux_bus.h>
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_device.h>
>  #include <drm/drm_edid.h>
> +#include <drm/drm_of.h>
>  #include <drm/drm_panel.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_probe_helper.h>
> @@ -1707,6 +1709,52 @@ struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp)
>  }
>  EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
>  
> +static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
> +{
> +	struct analogix_dp_device *dp = to_dp(aux);
> +	struct analogix_dp_plat_data *plat_data = dp->plat_data;
> +	int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
> +	int ret;
> +
> +	/*
> +	 * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no valid panel
> +	 * or bridge nodes. The driver should go on for the driver-free bridge or the DP
> +	 * mode applications.
> +	 */
> +	ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
> +					  &plat_data->panel, &plat_data->bridge);

Could you check if this can use a panel-bridge?
See for example 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/rockchip/rockchip_rgb.c#n138
or a lot of other places for drm_panel_bridge_add()

So if drm_of_find_panel_or_bridge() finds a bridge, just use it; if it
finds a panel, drm_panel_bridge_add() just wraps a bridge around it
and all the code can just assume everything is bridge after that.



> +	if (ret && ret != -ENODEV)
> +		return ret;
> +
> +	return component_add(dp->dev, plat_data->ops);
> +}
> +
> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp)
> +{
> +	int ret;
> +
> +	ret = devm_of_dp_aux_populate_bus(&dp->aux, analogix_dp_aux_done_probing);
> +	if (ret) {
> +		/*
> +		 * If devm_of_dp_aux_populate_bus() returns -ENODEV, the done_probing() will
> +		 * not be called because there are no EP devices. Then the callback function
> +		 * analogix_dp_aux_done_probing() will be called directly in order to support
> +		 * the other valid DT configurations.
> +		 *
> +		 * NOTE: The devm_of_dp_aux_populate_bus() is allowed to return -EPROBE_DEFER.
> +		 */
> +		if (ret != -ENODEV) {
> +			dev_err(dp->dev, "failed to populate aux bus\n");
> +			return ret;
> +		}
> +
> +		return analogix_dp_aux_done_probing(&dp->aux);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(analogix_dp_find_panel_or_bridge);
> +
>  MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
>  MODULE_DESCRIPTION("Analogix DP Core Driver");
>  MODULE_LICENSE("GPL v2");
> diff --git a/include/drm/bridge/analogix_dp.h b/include/drm/bridge/analogix_dp.h
> index 202e5eafb2cc..0b6d85f1924e 100644
> --- a/include/drm/bridge/analogix_dp.h
> +++ b/include/drm/bridge/analogix_dp.h
> @@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
>  	struct drm_bridge *bridge;
>  	struct drm_encoder *encoder;
>  	struct drm_connector *connector;
> +	const struct component_ops *ops;
>  
>  	int (*power_on)(struct analogix_dp_plat_data *);
>  	int (*power_off)(struct analogix_dp_plat_data *);
> @@ -52,5 +53,6 @@ int analogix_dp_stop_crc(struct drm_connector *connector);
>  
>  struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct drm_dp_aux *aux);
>  struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp);
>  
>  #endif /* _ANALOGIX_DP_H_ */
>

Re: [PATCH v2 07/12] drm/bridge: analogix_dp: Add support to find panel or bridge

Posted by Damon Ding 2 months, 4 weeks ago

Hi Heiko,

On 2025/7/10 4:07, Heiko Stübner wrote:
> Hi Damon,
> 
> Am Mittwoch, 9. Juli 2025, 09:01:34 Mitteleuropäische Sommerzeit schrieb Damon Ding:
>> Since the panel/bridge should logically be positioned behind the
>> Analogix bridge in the display pipeline, it makes sense to handle
>> the panel/bridge parsing on the Analogix side.
>>
>> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
>> ---
>>   .../drm/bridge/analogix/analogix_dp_core.c    | 48 +++++++++++++++++++
>>   include/drm/bridge/analogix_dp.h              |  2 +
>>   2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 78d68310e4f6..660f95e90490 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -19,12 +19,14 @@
>>   #include <linux/platform_device.h>
>>   
>>   #include <drm/bridge/analogix_dp.h>
>> +#include <drm/display/drm_dp_aux_bus.h>
>>   #include <drm/drm_atomic.h>
>>   #include <drm/drm_atomic_helper.h>
>>   #include <drm/drm_bridge.h>
>>   #include <drm/drm_crtc.h>
>>   #include <drm/drm_device.h>
>>   #include <drm/drm_edid.h>
>> +#include <drm/drm_of.h>
>>   #include <drm/drm_panel.h>
>>   #include <drm/drm_print.h>
>>   #include <drm/drm_probe_helper.h>
>> @@ -1707,6 +1709,52 @@ struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp)
>>   }
>>   EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
>>   
>> +static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
>> +{
>> +	struct analogix_dp_device *dp = to_dp(aux);
>> +	struct analogix_dp_plat_data *plat_data = dp->plat_data;
>> +	int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
>> +	int ret;
>> +
>> +	/*
>> +	 * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no valid panel
>> +	 * or bridge nodes. The driver should go on for the driver-free bridge or the DP
>> +	 * mode applications.
>> +	 */
>> +	ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
>> +					  &plat_data->panel, &plat_data->bridge);
> 
> Could you check if this can use a panel-bridge?
> See for example
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/rockchip/rockchip_rgb.c#n138
> or a lot of other places for drm_panel_bridge_add()
> 
> So if drm_of_find_panel_or_bridge() finds a bridge, just use it; if it
> finds a panel, drm_panel_bridge_add() just wraps a bridge around it
> and all the code can just assume everything is bridge after that.
> 
> 

Yes, that is a good approach. Using the panel-bridge will make the 
related checks more concise.

> 
>> +	if (ret && ret != -ENODEV)
>> +		return ret;
>> +
>> +	return component_add(dp->dev, plat_data->ops);
>> +}
>> +
>> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp)
>> +{
>> +	int ret;
>> +
>> +	ret = devm_of_dp_aux_populate_bus(&dp->aux, analogix_dp_aux_done_probing);
>> +	if (ret) {
>> +		/*
>> +		 * If devm_of_dp_aux_populate_bus() returns -ENODEV, the done_probing() will
>> +		 * not be called because there are no EP devices. Then the callback function
>> +		 * analogix_dp_aux_done_probing() will be called directly in order to support
>> +		 * the other valid DT configurations.
>> +		 *
>> +		 * NOTE: The devm_of_dp_aux_populate_bus() is allowed to return -EPROBE_DEFER.
>> +		 */
>> +		if (ret != -ENODEV) {
>> +			dev_err(dp->dev, "failed to populate aux bus\n");
>> +			return ret;
>> +		}
>> +
>> +		return analogix_dp_aux_done_probing(&dp->aux);
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(analogix_dp_find_panel_or_bridge);
>> +
>>   MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
>>   MODULE_DESCRIPTION("Analogix DP Core Driver");
>>   MODULE_LICENSE("GPL v2");
>> diff --git a/include/drm/bridge/analogix_dp.h b/include/drm/bridge/analogix_dp.h
>> index 202e5eafb2cc..0b6d85f1924e 100644
>> --- a/include/drm/bridge/analogix_dp.h
>> +++ b/include/drm/bridge/analogix_dp.h
>> @@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
>>   	struct drm_bridge *bridge;
>>   	struct drm_encoder *encoder;
>>   	struct drm_connector *connector;
>> +	const struct component_ops *ops;
>>   
>>   	int (*power_on)(struct analogix_dp_plat_data *);
>>   	int (*power_off)(struct analogix_dp_plat_data *);
>> @@ -52,5 +53,6 @@ int analogix_dp_stop_crc(struct drm_connector *connector);
>>   
>>   struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct drm_dp_aux *aux);
>>   struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
>> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp);
>>   
>>   #endif /* _ANALOGIX_DP_H_ */
>>
> 

Best regards,
Damon

Re: [PATCH v2 07/12] drm/bridge: analogix_dp: Add support to find panel or bridge

Posted by Damon Ding 2 months, 2 weeks ago

On 2025/7/11 15:41, Damon Ding wrote:
> Hi Heiko,
> 
> On 2025/7/10 4:07, Heiko Stübner wrote:
>> Hi Damon,
>>
>> Am Mittwoch, 9. Juli 2025, 09:01:34 Mitteleuropäische Sommerzeit 
>> schrieb Damon Ding:
>>> Since the panel/bridge should logically be positioned behind the
>>> Analogix bridge in the display pipeline, it makes sense to handle
>>> the panel/bridge parsing on the Analogix side.
>>>
>>> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
>>> ---
>>>   .../drm/bridge/analogix/analogix_dp_core.c    | 48 +++++++++++++++++++
>>>   include/drm/bridge/analogix_dp.h              |  2 +
>>>   2 files changed, 50 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/ 
>>> drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>>> index 78d68310e4f6..660f95e90490 100644
>>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>>> @@ -19,12 +19,14 @@
>>>   #include <linux/platform_device.h>
>>>   #include <drm/bridge/analogix_dp.h>
>>> +#include <drm/display/drm_dp_aux_bus.h>
>>>   #include <drm/drm_atomic.h>
>>>   #include <drm/drm_atomic_helper.h>
>>>   #include <drm/drm_bridge.h>
>>>   #include <drm/drm_crtc.h>
>>>   #include <drm/drm_device.h>
>>>   #include <drm/drm_edid.h>
>>> +#include <drm/drm_of.h>
>>>   #include <drm/drm_panel.h>
>>>   #include <drm/drm_print.h>
>>>   #include <drm/drm_probe_helper.h>
>>> @@ -1707,6 +1709,52 @@ struct drm_dp_aux *analogix_dp_get_aux(struct 
>>> analogix_dp_device *dp)
>>>   }
>>>   EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
>>> +static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
>>> +{
>>> +    struct analogix_dp_device *dp = to_dp(aux);
>>> +    struct analogix_dp_plat_data *plat_data = dp->plat_data;
>>> +    int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
>>> +    int ret;
>>> +
>>> +    /*
>>> +     * If drm_of_find_panel_or_bridge() returns -ENODEV, there may 
>>> be no valid panel
>>> +     * or bridge nodes. The driver should go on for the driver-free 
>>> bridge or the DP
>>> +     * mode applications.
>>> +     */
>>> +    ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
>>> +                      &plat_data->panel, &plat_data->bridge);
>>
>> Could you check if this can use a panel-bridge?
>> See for example
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 
>> tree/drivers/gpu/drm/rockchip/rockchip_rgb.c#n138
>> or a lot of other places for drm_panel_bridge_add()
>>
>> So if drm_of_find_panel_or_bridge() finds a bridge, just use it; if it
>> finds a panel, drm_panel_bridge_add() just wraps a bridge around it
>> and all the code can just assume everything is bridge after that.
>>
>>
> 
> Yes, that is a good approach. Using the panel-bridge will make the 
> related checks more concise.
> 
>>
>>> +    if (ret && ret != -ENODEV)
>>> +        return ret;
>>> +
>>> +    return component_add(dp->dev, plat_data->ops);
>>> +}
>>> +
>>> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp)
>>> +{
>>> +    int ret;
>>> +
>>> +    ret = devm_of_dp_aux_populate_bus(&dp->aux, 
>>> analogix_dp_aux_done_probing);
>>> +    if (ret) {
>>> +        /*
>>> +         * If devm_of_dp_aux_populate_bus() returns -ENODEV, the 
>>> done_probing() will
>>> +         * not be called because there are no EP devices. Then the 
>>> callback function
>>> +         * analogix_dp_aux_done_probing() will be called directly in 
>>> order to support
>>> +         * the other valid DT configurations.
>>> +         *
>>> +         * NOTE: The devm_of_dp_aux_populate_bus() is allowed to 
>>> return -EPROBE_DEFER.
>>> +         */
>>> +        if (ret != -ENODEV) {
>>> +            dev_err(dp->dev, "failed to populate aux bus\n");
>>> +            return ret;
>>> +        }
>>> +
>>> +        return analogix_dp_aux_done_probing(&dp->aux);
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(analogix_dp_find_panel_or_bridge);
>>> +
>>>   MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
>>>   MODULE_DESCRIPTION("Analogix DP Core Driver");
>>>   MODULE_LICENSE("GPL v2");
>>> diff --git a/include/drm/bridge/analogix_dp.h b/include/drm/bridge/ 
>>> analogix_dp.h
>>> index 202e5eafb2cc..0b6d85f1924e 100644
>>> --- a/include/drm/bridge/analogix_dp.h
>>> +++ b/include/drm/bridge/analogix_dp.h
>>> @@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
>>>       struct drm_bridge *bridge;
>>>       struct drm_encoder *encoder;
>>>       struct drm_connector *connector;
>>> +    const struct component_ops *ops;
>>>       int (*power_on)(struct analogix_dp_plat_data *);
>>>       int (*power_off)(struct analogix_dp_plat_data *);
>>> @@ -52,5 +53,6 @@ int analogix_dp_stop_crc(struct drm_connector 
>>> *connector);
>>>   struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct 
>>> drm_dp_aux *aux);
>>>   struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
>>> +int analogix_dp_find_panel_or_bridge(struct analogix_dp_device *dp);
>>>   #endif /* _ANALOGIX_DP_H_ */
>>>
>>
> 

While preparing the v3 patch series, I encountered a question regarding 
the mode retrieval process. The relevant code in 
drivers/gpu/drm/display/drm_bridge_connector.c is as follows:

static int drm_bridge_connector_get_modes(struct drm_connector *connector)
{
......
	/*
	 * If display exposes EDID, then we parse that in the normal way to
	 * build table of supported modes.
	 */
	bridge = bridge_connector->bridge_edid;
	if (bridge)
		return drm_bridge_connector_get_modes_edid(connector, bridge);

	/*
	 * Otherwise if the display pipeline reports modes (e.g. with a fixed
	 * resolution panel or an analog TV output), query it.
	 */
	bridge = bridge_connector->bridge_modes;
	if (bridge)
		return bridge->funcs->get_modes(bridge, connector);
......
}

The &drm_bridge_funcs.get_modes() will never be called if the 
bridge_connector supports DRM_BRIDGE_OP_EDID. This suggests that 
DRM_BRIDGE_OP_EDID and DRM_BRIDGE_OP_MODES might be mutually exclusive.
And the following comments also confirm it(include/drm/drm_bridge.h):

......
	/**
	 * @get_modes:
	 *
	 * Fill all modes currently valid for the sink into the &drm_connector
	 * with drm_mode_probed_add().
	 *
	 * The @get_modes callback is mostly intended to support non-probeable
	 * displays such as many fixed panels. Bridges that support reading
	 * EDID shall leave @get_modes unimplemented and implement the
	 * &drm_bridge_funcs->edid_read callback instead.
	 *
......

I want to use drm_panel_get_modes()/drm_bridge_get_modes() as a fallback 
when drm_bridge_connector_get_modes_edid() returns no modes, compatible 
with the historical behavior. Should I apply the related code with 
&drm_bridge_funcs.edid_read() then abandon the 
&drm_bridge_funcs.get_modes()? or the opposite?

Or maybe the DRM_BRIDGE_OP_MODES can be a certain fallback of 
DRM_BRIDGE_OP_EDID for the bridge_connector?

Best regards,
Damon