[v3,2/3] drm/msm/disp/dpu1: add helper to know if display is builtin

  Since DRM encoder type for few encoders can be similar
(like eDP and DP) find out if the interface supports HPD
from encoder bridge to differentiate between builtin
and pluggable displays.

Changes in v1:
- add connector type in the disp_info (Dmitry)
- add helper functions to know encoder type
- update commit text reflecting the change

Changes in v2:
- avoid hardcode of connector type for DSI as it may not be true (Dmitry)
- get the HPD information from encoder bridge

Changes in v3:
- use bridge type instead of bridge ops in determining connector (Dmitry)

Signed-off-by: Kalyan Thota <quic_kalyant@quicinc.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 27 +++++++++++++++++++++++++++
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  6 ++++++
 2 files changed, 33 insertions(+)
  

On 18/11/2022 15:16, Kalyan Thota wrote:
> Since DRM encoder type for few encoders can be similar
> (like eDP and DP) find out if the interface supports HPD
> from encoder bridge to differentiate between builtin
> and pluggable displays.
> 
> Changes in v1:
> - add connector type in the disp_info (Dmitry)
> - add helper functions to know encoder type
> - update commit text reflecting the change
> 
> Changes in v2:
> - avoid hardcode of connector type for DSI as it may not be true (Dmitry)
> - get the HPD information from encoder bridge
> 
> Changes in v3:
> - use bridge type instead of bridge ops in determining connector (Dmitry)
> 
> Signed-off-by: Kalyan Thota <quic_kalyant@quicinc.com>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 27 +++++++++++++++++++++++++++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  6 ++++++
>   2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 9c6817b..574f2b0 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -15,6 +15,7 @@
>   #include <drm/drm_crtc.h>
>   #include <drm/drm_file.h>
>   #include <drm/drm_probe_helper.h>
> +#include <drm/drm_bridge.h>
>   
>   #include "msm_drv.h"
>   #include "dpu_kms.h"
> @@ -217,6 +218,32 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
>   	15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
>   };
>   
> +bool dpu_encoder_is_builtin(struct drm_encoder *encoder)
> +{
> +	struct drm_bridge *bridge;
> +	int ops = 0;
> +
> +	if (!encoder)
> +		return false;
> +
> +	/* Get last bridge in the chain to determine connector type */
> +	drm_for_each_bridge_in_chain(encoder, bridge)
> +		if (!drm_bridge_get_next_bridge(bridge))
> +			ops = bridge->type;

Why don't we check the connector type directly? You should not assume 
that connector's type is equal to the latest bridge's type.

> +
> +	switch (ops) {
> +	case DRM_MODE_CONNECTOR_Unknown:
> +	case DRM_MODE_CONNECTOR_LVDS:
> +	case DRM_MODE_CONNECTOR_eDP:
> +	case DRM_MODE_CONNECTOR_DSI:
> +	case DRM_MODE_CONNECTOR_DPI:
> +	case DRM_MODE_CONNECTOR_WRITEBACK:
> +	case DRM_MODE_CONNECTOR_VIRTUAL:

Unknown, WRITEBACK and VIRTUAL are not builtin (for the point of CTM at 
least).

> +		return true;
> +	default:
> +		return false;
> +	}
> +}
>   
>   bool dpu_encoder_is_widebus_enabled(const struct drm_encoder *drm_enc)
>   {
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> index 9e7236e..7f3d823 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> @@ -224,4 +224,10 @@ void dpu_encoder_cleanup_wb_job(struct drm_encoder *drm_enc,
>    */
>   bool dpu_encoder_is_valid_for_commit(struct drm_encoder *drm_enc);
>   
> +/**
> + * dpu_encoder_is_builtin - find if the encoder is of type builtin
> + * @drm_enc:    Pointer to previously created drm encoder structure
> + */
> +bool dpu_encoder_is_builtin(struct drm_encoder *drm_enc);
> +
>   #endif /* __DPU_ENCODER_H__ */
  

>-----Original Message-----
>From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>Sent: Friday, November 18, 2022 6:09 PM
>To: Kalyan Thota (QUIC) <quic_kalyant@quicinc.com>; dri-
>devel@lists.freedesktop.org; linux-arm-msm@vger.kernel.org;
>freedreno@lists.freedesktop.org; devicetree@vger.kernel.org
>Cc: linux-kernel@vger.kernel.org; robdclark@chromium.org;
>dianders@chromium.org; swboyd@chromium.org; Vinod Polimera (QUIC)
><quic_vpolimer@quicinc.com>; Abhinav Kumar (QUIC)
><quic_abhinavk@quicinc.com>
>Subject: Re: [PATCH v3 2/3] drm/msm/disp/dpu1: add helper to know if display is
>builtin
>
>WARNING: This email originated from outside of Qualcomm. Please be wary of
>any links or attachments, and do not enable macros.
>
>On 18/11/2022 15:16, Kalyan Thota wrote:
>> Since DRM encoder type for few encoders can be similar (like eDP and
>> DP) find out if the interface supports HPD from encoder bridge to
>> differentiate between builtin and pluggable displays.
>>
>> Changes in v1:
>> - add connector type in the disp_info (Dmitry)
>> - add helper functions to know encoder type
>> - update commit text reflecting the change
>>
>> Changes in v2:
>> - avoid hardcode of connector type for DSI as it may not be true
>> (Dmitry)
>> - get the HPD information from encoder bridge
>>
>> Changes in v3:
>> - use bridge type instead of bridge ops in determining connector
>> (Dmitry)
>>
>> Signed-off-by: Kalyan Thota <quic_kalyant@quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 27
>+++++++++++++++++++++++++++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  6 ++++++
>>   2 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index 9c6817b..574f2b0 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -15,6 +15,7 @@
>>   #include <drm/drm_crtc.h>
>>   #include <drm/drm_file.h>
>>   #include <drm/drm_probe_helper.h>
>> +#include <drm/drm_bridge.h>
>>
>>   #include "msm_drv.h"
>>   #include "dpu_kms.h"
>> @@ -217,6 +218,32 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
>>       15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
>>   };
>>
>> +bool dpu_encoder_is_builtin(struct drm_encoder *encoder) {
>> +     struct drm_bridge *bridge;
>> +     int ops = 0;
>> +
>> +     if (!encoder)
>> +             return false;
>> +
>> +     /* Get last bridge in the chain to determine connector type */
>> +     drm_for_each_bridge_in_chain(encoder, bridge)
>> +             if (!drm_bridge_get_next_bridge(bridge))
>> +                     ops = bridge->type;
>
>Why don't we check the connector type directly? You should not assume that
>connector's type is equal to the latest bridge's type.

if we need to get the type from connector, need to do something as below.
Are you thinking on the same lines ?

"to_drm_bridge_connector" macro needs to be moved to drm_bridge_connector.h

struct drm_bridge_connector *bridge_connector;

drm_connector_list_iter_begin(dev, &conn_iter);
	drm_for_each_connector_iter(connector, &conn_iter) {

		bridge_connector = to_drm_bridge_connector(connector);
		if (bridge_connector->encoder == encoder) {
			type = connector->connector_type;
			break;
		}
	}
drm_connector_list_iter_end(&conn_iter);


>> +
>> +     switch (ops) {
>> +     case DRM_MODE_CONNECTOR_Unknown:
>> +     case DRM_MODE_CONNECTOR_LVDS:
>> +     case DRM_MODE_CONNECTOR_eDP:
>> +     case DRM_MODE_CONNECTOR_DSI:
>> +     case DRM_MODE_CONNECTOR_DPI:
>> +     case DRM_MODE_CONNECTOR_WRITEBACK:
>> +     case DRM_MODE_CONNECTOR_VIRTUAL:
>
>Unknown, WRITEBACK and VIRTUAL are not builtin (for the point of CTM at
>least).
>
>> +             return true;
>> +     default:
>> +             return false;
>> +     }
>> +}
>>
>>   bool dpu_encoder_is_widebus_enabled(const struct drm_encoder *drm_enc)
>>   {
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> index 9e7236e..7f3d823 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> @@ -224,4 +224,10 @@ void dpu_encoder_cleanup_wb_job(struct
>drm_encoder *drm_enc,
>>    */
>>   bool dpu_encoder_is_valid_for_commit(struct drm_encoder *drm_enc);
>>
>> +/**
>> + * dpu_encoder_is_builtin - find if the encoder is of type builtin
>> + * @drm_enc:    Pointer to previously created drm encoder structure
>> + */
>> +bool dpu_encoder_is_builtin(struct drm_encoder *drm_enc);
>> +
>>   #endif /* __DPU_ENCODER_H__ */
>
>--
>With best wishes
>Dmitry
  

On 18/11/2022 16:37, Kalyan Thota wrote:
> 
> 
>> -----Original Message-----
>> From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> Sent: Friday, November 18, 2022 6:09 PM
>> To: Kalyan Thota (QUIC) <quic_kalyant@quicinc.com>; dri-
>> devel@lists.freedesktop.org; linux-arm-msm@vger.kernel.org;
>> freedreno@lists.freedesktop.org; devicetree@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org; robdclark@chromium.org;
>> dianders@chromium.org; swboyd@chromium.org; Vinod Polimera (QUIC)
>> <quic_vpolimer@quicinc.com>; Abhinav Kumar (QUIC)
>> <quic_abhinavk@quicinc.com>
>> Subject: Re: [PATCH v3 2/3] drm/msm/disp/dpu1: add helper to know if display is
>> builtin
>>
>> WARNING: This email originated from outside of Qualcomm. Please be wary of
>> any links or attachments, and do not enable macros.
>>
>> On 18/11/2022 15:16, Kalyan Thota wrote:
>>> Since DRM encoder type for few encoders can be similar (like eDP and
>>> DP) find out if the interface supports HPD from encoder bridge to
>>> differentiate between builtin and pluggable displays.
>>>
>>> Changes in v1:
>>> - add connector type in the disp_info (Dmitry)
>>> - add helper functions to know encoder type
>>> - update commit text reflecting the change
>>>
>>> Changes in v2:
>>> - avoid hardcode of connector type for DSI as it may not be true
>>> (Dmitry)
>>> - get the HPD information from encoder bridge
>>>
>>> Changes in v3:
>>> - use bridge type instead of bridge ops in determining connector
>>> (Dmitry)
>>>
>>> Signed-off-by: Kalyan Thota <quic_kalyant@quicinc.com>
>>> ---
>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 27
>> +++++++++++++++++++++++++++
>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  6 ++++++
>>>    2 files changed, 33 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> index 9c6817b..574f2b0 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> @@ -15,6 +15,7 @@
>>>    #include <drm/drm_crtc.h>
>>>    #include <drm/drm_file.h>
>>>    #include <drm/drm_probe_helper.h>
>>> +#include <drm/drm_bridge.h>
>>>
>>>    #include "msm_drv.h"
>>>    #include "dpu_kms.h"
>>> @@ -217,6 +218,32 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
>>>        15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
>>>    };
>>>
>>> +bool dpu_encoder_is_builtin(struct drm_encoder *encoder) {
>>> +     struct drm_bridge *bridge;
>>> +     int ops = 0;
>>> +
>>> +     if (!encoder)
>>> +             return false;
>>> +
>>> +     /* Get last bridge in the chain to determine connector type */
>>> +     drm_for_each_bridge_in_chain(encoder, bridge)
>>> +             if (!drm_bridge_get_next_bridge(bridge))
>>> +                     ops = bridge->type;
>>
>> Why don't we check the connector type directly? You should not assume that
>> connector's type is equal to the latest bridge's type.
> 
> if we need to get the type from connector, need to do something as below.
> Are you thinking on the same lines ?
> 
> "to_drm_bridge_connector" macro needs to be moved to drm_bridge_connector.h
> 
> struct drm_bridge_connector *bridge_connector;
> 
> drm_connector_list_iter_begin(dev, &conn_iter);
> 	drm_for_each_connector_iter(connector, &conn_iter) {
> 
> 		bridge_connector = to_drm_bridge_connector(connector);
> 		if (bridge_connector->encoder == encoder) {
> 			type = connector->connector_type;
> 			break;
> 		}
> 	}
> drm_connector_list_iter_end(&conn_iter);

No. You can not depend on the idea that every connector is 
drm_bridge_connector. Some bridges might create their own connectors. 
However you can do it in the following way:

drm_connector_list_iter_begin(dev, &iter);
drm_for_each_connector_iter(connector, &iter) {
  if (connector->possible_encoders & drm_encoder_mask(encoder)) {
     builtin = (connector->connector_type == DRM_MODE_CONNECTOR_LVDS) || 
...;
     break;
   }
}
drm_connector_list_iter_end(&iter);

return builtin;


> 
> 
>>> +
>>> +     switch (ops) {
>>> +     case DRM_MODE_CONNECTOR_Unknown:
>>> +     case DRM_MODE_CONNECTOR_LVDS:
>>> +     case DRM_MODE_CONNECTOR_eDP:
>>> +     case DRM_MODE_CONNECTOR_DSI:
>>> +     case DRM_MODE_CONNECTOR_DPI:
>>> +     case DRM_MODE_CONNECTOR_WRITEBACK:
>>> +     case DRM_MODE_CONNECTOR_VIRTUAL:
>>
>> Unknown, WRITEBACK and VIRTUAL are not builtin (for the point of CTM at
>> least).
>>
>>> +             return true;
>>> +     default:
>>> +             return false;
>>> +     }
>>> +}
>>>
>>>    bool dpu_encoder_is_widebus_enabled(const struct drm_encoder *drm_enc)
>>>    {
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>>> index 9e7236e..7f3d823 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>>> @@ -224,4 +224,10 @@ void dpu_encoder_cleanup_wb_job(struct
>> drm_encoder *drm_enc,
>>>     */
>>>    bool dpu_encoder_is_valid_for_commit(struct drm_encoder *drm_enc);
>>>
>>> +/**
>>> + * dpu_encoder_is_builtin - find if the encoder is of type builtin
>>> + * @drm_enc:    Pointer to previously created drm encoder structure
>>> + */
>>> +bool dpu_encoder_is_builtin(struct drm_encoder *drm_enc);
>>> +
>>>    #endif /* __DPU_ENCODER_H__ */
>>
>> --
>> With best wishes
>> Dmitry
>