diff mbox

[v3,4/7] drm/atmel-hlcdc: support bus-width (12/16/18/24) in endpoint nodes

Message ID 20180419162751.25223-5-peda@axentia.se (mailing list archive)
State New, archived
Headers show

Commit Message

Peter Rosin April 19, 2018, 4:27 p.m. UTC
This beats the heuristic that the connector is involved in what format
should be output for cases where this fails.

E.g. if there is a bridge that changes format between the encoder and the
connector, or if some of the RGB pins between the lcd controller and the
encoder are not routed on the PCB.

This is critical for the devices that have the "conflicting output
formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant
RGB bits move around depending on the selected output mode. For
devices that do not have the "conflicting output formats" issue
(SAMA5D2, SAMA5D4), this is completely irrelevant.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c   | 71 +++++++++++++++++-------
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h     |  2 +
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c | 40 ++++++++++++-
 3 files changed, 92 insertions(+), 21 deletions(-)

Comments

Boris Brezillon April 21, 2018, 4:19 p.m. UTC | #1
On Thu, 19 Apr 2018 18:27:48 +0200
Peter Rosin <peda@axentia.se> wrote:

> This beats the heuristic that the connector is involved in what format
> should be output for cases where this fails.
> 
> E.g. if there is a bridge that changes format between the encoder and the
> connector, or if some of the RGB pins between the lcd controller and the
> encoder are not routed on the PCB.
> 
> This is critical for the devices that have the "conflicting output
> formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant
> RGB bits move around depending on the selected output mode. For
> devices that do not have the "conflicting output formats" issue
> (SAMA5D2, SAMA5D4), this is completely irrelevant.
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c   | 71 +++++++++++++++++-------
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h     |  2 +
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c | 40 ++++++++++++-
>  3 files changed, 92 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> index d73281095fac..b4e7f5b6f497 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> @@ -226,6 +226,56 @@ static void atmel_hlcdc_crtc_atomic_enable(struct drm_crtc *c,
>  #define ATMEL_HLCDC_RGB888_OUTPUT	BIT(3)
>  #define ATMEL_HLCDC_OUTPUT_MODE_MASK	GENMASK(3, 0)
>  
> +static int atmel_hlcdc_connector_output_mode(struct drm_connector_state *state)
> +{
> +	struct drm_connector *connector = state->connector;
> +	struct atmel_hlcdc_dc *dc = connector->dev->dev_private;
> +	struct drm_encoder *encoder;
> +	struct drm_display_info *info = &connector->display_info;
> +	unsigned int supported_fmts = 0;
> +	int j;
> +
> +	encoder = state->best_encoder;
> +	if (!encoder)
> +		encoder = connector->encoder;
> +
> +	switch (dc->bus_fmt[encoder->index]) {
> +	case 0:
> +		break;
> +	case MEDIA_BUS_FMT_RGB444_1X12:
> +		return ATMEL_HLCDC_RGB444_OUTPUT;
> +	case MEDIA_BUS_FMT_RGB565_1X16:
> +		return ATMEL_HLCDC_RGB565_OUTPUT;
> +	case MEDIA_BUS_FMT_RGB666_1X18:
> +		return ATMEL_HLCDC_RGB666_OUTPUT;
> +	case MEDIA_BUS_FMT_RGB888_1X24:
> +		return ATMEL_HLCDC_RGB888_OUTPUT;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	for (j = 0; j < info->num_bus_formats; j++) {
> +		switch (info->bus_formats[j]) {
> +		case MEDIA_BUS_FMT_RGB444_1X12:
> +			supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
> +			break;
> +		case MEDIA_BUS_FMT_RGB565_1X16:
> +			supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
> +			break;
> +		case MEDIA_BUS_FMT_RGB666_1X18:
> +			supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
> +			break;
> +		case MEDIA_BUS_FMT_RGB888_1X24:
> +			supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
> +			break;
> +		default:
> +			break;
> +		}
> +	}
> +
> +	return supported_fmts;
> +}
> +
>  static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
>  {
>  	unsigned int output_fmts = ATMEL_HLCDC_OUTPUT_MODE_MASK;
> @@ -238,31 +288,12 @@ static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
>  	crtc = drm_crtc_to_atmel_hlcdc_crtc(state->crtc);
>  
>  	for_each_new_connector_in_state(state->state, connector, cstate, i) {
> -		struct drm_display_info *info = &connector->display_info;
>  		unsigned int supported_fmts = 0;
> -		int j;
>  
>  		if (!cstate->crtc)
>  			continue;
>  
> -		for (j = 0; j < info->num_bus_formats; j++) {
> -			switch (info->bus_formats[j]) {
> -			case MEDIA_BUS_FMT_RGB444_1X12:
> -				supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
> -				break;
> -			case MEDIA_BUS_FMT_RGB565_1X16:
> -				supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
> -				break;
> -			case MEDIA_BUS_FMT_RGB666_1X18:
> -				supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
> -				break;
> -			case MEDIA_BUS_FMT_RGB888_1X24:
> -				supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
> -				break;
> -			default:
> -				break;
> -			}
> -		}
> +		supported_fmts = atmel_hlcdc_connector_output_mode(cstate);
>  
>  		if (crtc->dc->desc->conflicting_output_formats)
>  			output_fmts &= supported_fmts;
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> index ab32d5b268d2..be2d180dd169 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> @@ -365,6 +365,7 @@ struct atmel_hlcdc_plane_properties {
>   * @hlcdc: pointer to the atmel_hlcdc structure provided by the MFD device
>   * @fbdev: framebuffer device attached to the Display Controller
>   * @crtc: CRTC provided by the display controller
> + * @bus_fmt: Array of bus format overrides, per connector.
>   * @planes: instantiated planes
>   * @layers: active HLCDC layers
>   * @wq: display controller workqueue
> @@ -376,6 +377,7 @@ struct atmel_hlcdc_dc {
>  	struct dma_pool *dscrpool;
>  	struct atmel_hlcdc *hlcdc;
>  	struct drm_crtc *crtc;
> +	int *bus_fmt;

Looks like this bus_fmt information should be attached to the
atmel_hlcdc_rgb_output object, since the property is placed in the
endpoint representing the DPI encoder output.

You could then parse the format in atmel_hlcdc_attach_endpoint() and
provide a helper to retrieve the hardcoded bus-format attached to an
encoder:

  int atmel_hlcdc_encoder_get_bus_fmt(struct drm_encoder *encoder);

and if it returns zero you can fallback to bus formats
defined in drm_display_info, as you do in this patch.

>  	struct atmel_hlcdc_layer *layers[ATMEL_HLCDC_MAX_LAYERS];
>  	struct workqueue_struct *wq;
>  	struct {
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> index 8db51fb131db..8787e2890c93 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> @@ -77,10 +77,48 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
>  
>  int atmel_hlcdc_create_outputs(struct drm_device *dev)
>  {
> +	struct atmel_hlcdc_dc *dc = dev->dev_private;
> +	struct device_node *ep;
> +	int count = of_graph_get_endpoint_count(dev->dev->of_node);
>  	int endpoint, ret = 0;
>  
> -	for (endpoint = 0; !ret; endpoint++)
> +	/*
> +	 * Assume that each endpoint will create a single encoder
> +	 * so that the encoder index can be used as index into
> +	 * this bus_fmt array.
> +	 */
> +	dc->bus_fmt = devm_kzalloc(dev->dev, count * sizeof(*dc->bus_fmt),
> +				   GFP_KERNEL);
> +	if (!dc->bus_fmt)
> +		return -ENOMEM;
> +
> +	for (endpoint = 0; !ret; endpoint++) {
> +		ep = of_graph_get_endpoint_by_regs(dev->dev->of_node, 0,
> +						   endpoint);
> +		if (!ep) {
> +			ret = -ENODEV;
> +			break;
> +		}
> +
> +		dc->bus_fmt[endpoint] = drm_of_media_bus_fmt(ep);
> +
> +		switch (dc->bus_fmt[endpoint]) {
> +		case 0:
> +		case MEDIA_BUS_FMT_RGB444_1X12:
> +		case MEDIA_BUS_FMT_RGB565_1X16:
> +		case MEDIA_BUS_FMT_RGB666_1X18:
> +		case MEDIA_BUS_FMT_RGB888_1X24:
> +			break;
> +		default:
> +			ret = dc->bus_fmt[endpoint];
> +			if (ret > 0)
> +				ret = -EINVAL;
> +		}
> +		if (ret < 0)
> +			break;
> +
>  		ret = atmel_hlcdc_attach_endpoint(dev, endpoint);
> +	}
>  
>  	/* At least one device was successfully attached.*/
>  	if (ret == -ENODEV && endpoint)
Peter Rosin April 21, 2018, 10:13 p.m. UTC | #2
On 2018-04-21 18:19, Boris Brezillon wrote:
> On Thu, 19 Apr 2018 18:27:48 +0200
> Peter Rosin <peda@axentia.se> wrote:
> 
>> This beats the heuristic that the connector is involved in what format
>> should be output for cases where this fails.
>>
>> E.g. if there is a bridge that changes format between the encoder and the
>> connector, or if some of the RGB pins between the lcd controller and the
>> encoder are not routed on the PCB.
>>
>> This is critical for the devices that have the "conflicting output
>> formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant
>> RGB bits move around depending on the selected output mode. For
>> devices that do not have the "conflicting output formats" issue
>> (SAMA5D2, SAMA5D4), this is completely irrelevant.
>>
>> Signed-off-by: Peter Rosin <peda@axentia.se>
>> ---
>>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c   | 71 +++++++++++++++++-------
>>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h     |  2 +
>>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c | 40 ++++++++++++-
>>  3 files changed, 92 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
>> index d73281095fac..b4e7f5b6f497 100644
>> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
>> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
>> @@ -226,6 +226,56 @@ static void atmel_hlcdc_crtc_atomic_enable(struct drm_crtc *c,
>>  #define ATMEL_HLCDC_RGB888_OUTPUT	BIT(3)
>>  #define ATMEL_HLCDC_OUTPUT_MODE_MASK	GENMASK(3, 0)
>>  
>> +static int atmel_hlcdc_connector_output_mode(struct drm_connector_state *state)
>> +{
>> +	struct drm_connector *connector = state->connector;
>> +	struct atmel_hlcdc_dc *dc = connector->dev->dev_private;
>> +	struct drm_encoder *encoder;
>> +	struct drm_display_info *info = &connector->display_info;
>> +	unsigned int supported_fmts = 0;
>> +	int j;
>> +
>> +	encoder = state->best_encoder;
>> +	if (!encoder)
>> +		encoder = connector->encoder;
>> +
>> +	switch (dc->bus_fmt[encoder->index]) {
>> +	case 0:
>> +		break;
>> +	case MEDIA_BUS_FMT_RGB444_1X12:
>> +		return ATMEL_HLCDC_RGB444_OUTPUT;
>> +	case MEDIA_BUS_FMT_RGB565_1X16:
>> +		return ATMEL_HLCDC_RGB565_OUTPUT;
>> +	case MEDIA_BUS_FMT_RGB666_1X18:
>> +		return ATMEL_HLCDC_RGB666_OUTPUT;
>> +	case MEDIA_BUS_FMT_RGB888_1X24:
>> +		return ATMEL_HLCDC_RGB888_OUTPUT;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	for (j = 0; j < info->num_bus_formats; j++) {
>> +		switch (info->bus_formats[j]) {
>> +		case MEDIA_BUS_FMT_RGB444_1X12:
>> +			supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
>> +			break;
>> +		case MEDIA_BUS_FMT_RGB565_1X16:
>> +			supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
>> +			break;
>> +		case MEDIA_BUS_FMT_RGB666_1X18:
>> +			supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
>> +			break;
>> +		case MEDIA_BUS_FMT_RGB888_1X24:
>> +			supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
>> +			break;
>> +		default:
>> +			break;
>> +		}
>> +	}
>> +
>> +	return supported_fmts;
>> +}
>> +
>>  static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
>>  {
>>  	unsigned int output_fmts = ATMEL_HLCDC_OUTPUT_MODE_MASK;
>> @@ -238,31 +288,12 @@ static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
>>  	crtc = drm_crtc_to_atmel_hlcdc_crtc(state->crtc);
>>  
>>  	for_each_new_connector_in_state(state->state, connector, cstate, i) {
>> -		struct drm_display_info *info = &connector->display_info;
>>  		unsigned int supported_fmts = 0;
>> -		int j;
>>  
>>  		if (!cstate->crtc)
>>  			continue;
>>  
>> -		for (j = 0; j < info->num_bus_formats; j++) {
>> -			switch (info->bus_formats[j]) {
>> -			case MEDIA_BUS_FMT_RGB444_1X12:
>> -				supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
>> -				break;
>> -			case MEDIA_BUS_FMT_RGB565_1X16:
>> -				supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
>> -				break;
>> -			case MEDIA_BUS_FMT_RGB666_1X18:
>> -				supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
>> -				break;
>> -			case MEDIA_BUS_FMT_RGB888_1X24:
>> -				supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
>> -				break;
>> -			default:
>> -				break;
>> -			}
>> -		}
>> +		supported_fmts = atmel_hlcdc_connector_output_mode(cstate);
>>  
>>  		if (crtc->dc->desc->conflicting_output_formats)
>>  			output_fmts &= supported_fmts;
>> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
>> index ab32d5b268d2..be2d180dd169 100644
>> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
>> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
>> @@ -365,6 +365,7 @@ struct atmel_hlcdc_plane_properties {
>>   * @hlcdc: pointer to the atmel_hlcdc structure provided by the MFD device
>>   * @fbdev: framebuffer device attached to the Display Controller
>>   * @crtc: CRTC provided by the display controller
>> + * @bus_fmt: Array of bus format overrides, per connector.
>>   * @planes: instantiated planes
>>   * @layers: active HLCDC layers
>>   * @wq: display controller workqueue
>> @@ -376,6 +377,7 @@ struct atmel_hlcdc_dc {
>>  	struct dma_pool *dscrpool;
>>  	struct atmel_hlcdc *hlcdc;
>>  	struct drm_crtc *crtc;
>> +	int *bus_fmt;
> 
> Looks like this bus_fmt information should be attached to the
> atmel_hlcdc_rgb_output object, since the property is placed in the
> endpoint representing the DPI encoder output.
> 
> You could then parse the format in atmel_hlcdc_attach_endpoint() and
> provide a helper to retrieve the hardcoded bus-format attached to an
> encoder:
> 
>   int atmel_hlcdc_encoder_get_bus_fmt(struct drm_encoder *encoder);
> 
> and if it returns zero you can fallback to bus formats
> defined in drm_display_info, as you do in this patch.

Good suggestion. However, it appears the atmel_hlcdc_rgb_output object
was removed in 4.13. But I'm bringing it back like this

struct atmel_hlcdc_rgb_output {
	struct drm_encoder encoder;
	int bus_fmt;
};

and adjusting the code to match that. It all looks nice and tidy, methinks.

v4 coming up Monday, if nothing unexpected happens.

Cheers,
Peter
diff mbox

Patch

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index d73281095fac..b4e7f5b6f497 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -226,6 +226,56 @@  static void atmel_hlcdc_crtc_atomic_enable(struct drm_crtc *c,
 #define ATMEL_HLCDC_RGB888_OUTPUT	BIT(3)
 #define ATMEL_HLCDC_OUTPUT_MODE_MASK	GENMASK(3, 0)
 
+static int atmel_hlcdc_connector_output_mode(struct drm_connector_state *state)
+{
+	struct drm_connector *connector = state->connector;
+	struct atmel_hlcdc_dc *dc = connector->dev->dev_private;
+	struct drm_encoder *encoder;
+	struct drm_display_info *info = &connector->display_info;
+	unsigned int supported_fmts = 0;
+	int j;
+
+	encoder = state->best_encoder;
+	if (!encoder)
+		encoder = connector->encoder;
+
+	switch (dc->bus_fmt[encoder->index]) {
+	case 0:
+		break;
+	case MEDIA_BUS_FMT_RGB444_1X12:
+		return ATMEL_HLCDC_RGB444_OUTPUT;
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		return ATMEL_HLCDC_RGB565_OUTPUT;
+	case MEDIA_BUS_FMT_RGB666_1X18:
+		return ATMEL_HLCDC_RGB666_OUTPUT;
+	case MEDIA_BUS_FMT_RGB888_1X24:
+		return ATMEL_HLCDC_RGB888_OUTPUT;
+	default:
+		return -EINVAL;
+	}
+
+	for (j = 0; j < info->num_bus_formats; j++) {
+		switch (info->bus_formats[j]) {
+		case MEDIA_BUS_FMT_RGB444_1X12:
+			supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
+			break;
+		case MEDIA_BUS_FMT_RGB565_1X16:
+			supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
+			break;
+		case MEDIA_BUS_FMT_RGB666_1X18:
+			supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
+			break;
+		case MEDIA_BUS_FMT_RGB888_1X24:
+			supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
+			break;
+		default:
+			break;
+		}
+	}
+
+	return supported_fmts;
+}
+
 static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
 {
 	unsigned int output_fmts = ATMEL_HLCDC_OUTPUT_MODE_MASK;
@@ -238,31 +288,12 @@  static int atmel_hlcdc_crtc_select_output_mode(struct drm_crtc_state *state)
 	crtc = drm_crtc_to_atmel_hlcdc_crtc(state->crtc);
 
 	for_each_new_connector_in_state(state->state, connector, cstate, i) {
-		struct drm_display_info *info = &connector->display_info;
 		unsigned int supported_fmts = 0;
-		int j;
 
 		if (!cstate->crtc)
 			continue;
 
-		for (j = 0; j < info->num_bus_formats; j++) {
-			switch (info->bus_formats[j]) {
-			case MEDIA_BUS_FMT_RGB444_1X12:
-				supported_fmts |= ATMEL_HLCDC_RGB444_OUTPUT;
-				break;
-			case MEDIA_BUS_FMT_RGB565_1X16:
-				supported_fmts |= ATMEL_HLCDC_RGB565_OUTPUT;
-				break;
-			case MEDIA_BUS_FMT_RGB666_1X18:
-				supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
-				break;
-			case MEDIA_BUS_FMT_RGB888_1X24:
-				supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
-				break;
-			default:
-				break;
-			}
-		}
+		supported_fmts = atmel_hlcdc_connector_output_mode(cstate);
 
 		if (crtc->dc->desc->conflicting_output_formats)
 			output_fmts &= supported_fmts;
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
index ab32d5b268d2..be2d180dd169 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
@@ -365,6 +365,7 @@  struct atmel_hlcdc_plane_properties {
  * @hlcdc: pointer to the atmel_hlcdc structure provided by the MFD device
  * @fbdev: framebuffer device attached to the Display Controller
  * @crtc: CRTC provided by the display controller
+ * @bus_fmt: Array of bus format overrides, per connector.
  * @planes: instantiated planes
  * @layers: active HLCDC layers
  * @wq: display controller workqueue
@@ -376,6 +377,7 @@  struct atmel_hlcdc_dc {
 	struct dma_pool *dscrpool;
 	struct atmel_hlcdc *hlcdc;
 	struct drm_crtc *crtc;
+	int *bus_fmt;
 	struct atmel_hlcdc_layer *layers[ATMEL_HLCDC_MAX_LAYERS];
 	struct workqueue_struct *wq;
 	struct {
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
index 8db51fb131db..8787e2890c93 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
@@ -77,10 +77,48 @@  static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
 
 int atmel_hlcdc_create_outputs(struct drm_device *dev)
 {
+	struct atmel_hlcdc_dc *dc = dev->dev_private;
+	struct device_node *ep;
+	int count = of_graph_get_endpoint_count(dev->dev->of_node);
 	int endpoint, ret = 0;
 
-	for (endpoint = 0; !ret; endpoint++)
+	/*
+	 * Assume that each endpoint will create a single encoder
+	 * so that the encoder index can be used as index into
+	 * this bus_fmt array.
+	 */
+	dc->bus_fmt = devm_kzalloc(dev->dev, count * sizeof(*dc->bus_fmt),
+				   GFP_KERNEL);
+	if (!dc->bus_fmt)
+		return -ENOMEM;
+
+	for (endpoint = 0; !ret; endpoint++) {
+		ep = of_graph_get_endpoint_by_regs(dev->dev->of_node, 0,
+						   endpoint);
+		if (!ep) {
+			ret = -ENODEV;
+			break;
+		}
+
+		dc->bus_fmt[endpoint] = drm_of_media_bus_fmt(ep);
+
+		switch (dc->bus_fmt[endpoint]) {
+		case 0:
+		case MEDIA_BUS_FMT_RGB444_1X12:
+		case MEDIA_BUS_FMT_RGB565_1X16:
+		case MEDIA_BUS_FMT_RGB666_1X18:
+		case MEDIA_BUS_FMT_RGB888_1X24:
+			break;
+		default:
+			ret = dc->bus_fmt[endpoint];
+			if (ret > 0)
+				ret = -EINVAL;
+		}
+		if (ret < 0)
+			break;
+
 		ret = atmel_hlcdc_attach_endpoint(dev, endpoint);
+	}
 
 	/* At least one device was successfully attached.*/
 	if (ret == -ENODEV && endpoint)