Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders

[H. Nikolaus Schaller]

Hi Paul,
thanks for another update.

We have been delayed to rework the CI20 HDMI code on top of your series
but it basically works in some situations. There is for example a problem
if the EDID reports DRM_COLOR_FORMAT_YCRCB422 but it appears to be outside
of your series.

The only issue we have is described below.

> Am 22.09.2021 um 22:55 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:
> 
> Attach a top-level bridge to each encoder, which will be used for
> negociating the bus format and flags.
> 
> All the bridges are now attached with DRM_BRIDGE_ATTACH_NO_CONNECTOR.
> 
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 92 +++++++++++++++++------
> 1 file changed, 70 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index a5e2880e07a1..a05a9fa6e115 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -21,6 +21,7 @@
> #include <drm/drm_atomic.h>
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_bridge.h>
> +#include <drm/drm_bridge_connector.h>
> #include <drm/drm_color_mgmt.h>
> #include <drm/drm_crtc.h>
> #include <drm/drm_crtc_helper.h>
> @@ -108,6 +109,19 @@ struct ingenic_drm {
> 	struct drm_private_obj private_obj;
> };
> 
> +struct ingenic_drm_bridge {
> +	struct drm_encoder encoder;
> +	struct drm_bridge bridge, *next_bridge;
> +
> +	struct drm_bus_cfg bus_cfg;
> +};
> +
> +static inline struct ingenic_drm_bridge *
> +to_ingenic_drm_bridge(struct drm_encoder *encoder)
> +{
> +	return container_of(encoder, struct ingenic_drm_bridge, encoder);
> +}
> +
> static inline struct ingenic_drm_private_state *
> to_ingenic_drm_priv_state(struct drm_private_state *state)
> {
> @@ -668,11 +682,10 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
> {
> 	struct ingenic_drm *priv = drm_device_get_priv(encoder->dev);
> 	struct drm_display_mode *mode = &crtc_state->adjusted_mode;
> -	struct drm_connector *conn = conn_state->connector;
> -	struct drm_display_info *info = &conn->display_info;
> +	struct ingenic_drm_bridge *bridge = to_ingenic_drm_bridge(encoder);
> 	unsigned int cfg, rgbcfg = 0;
> 
> -	priv->panel_is_sharp = info->bus_flags & DRM_BUS_FLAG_SHARP_SIGNALS;
> +	priv->panel_is_sharp = bridge->bus_cfg.flags & DRM_BUS_FLAG_SHARP_SIGNALS;
> 
> 	if (priv->panel_is_sharp) {
> 		cfg = JZ_LCD_CFG_MODE_SPECIAL_TFT_1 | JZ_LCD_CFG_REV_POLARITY;
> @@ -685,19 +698,19 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
> 		cfg |= JZ_LCD_CFG_HSYNC_ACTIVE_LOW;
> 	if (mode->flags & DRM_MODE_FLAG_NVSYNC)
> 		cfg |= JZ_LCD_CFG_VSYNC_ACTIVE_LOW;
> -	if (info->bus_flags & DRM_BUS_FLAG_DE_LOW)
> +	if (bridge->bus_cfg.flags & DRM_BUS_FLAG_DE_LOW)
> 		cfg |= JZ_LCD_CFG_DE_ACTIVE_LOW;
> -	if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
> +	if (bridge->bus_cfg.flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
> 		cfg |= JZ_LCD_CFG_PCLK_FALLING_EDGE;
> 
> 	if (!priv->panel_is_sharp) {
> -		if (conn->connector_type == DRM_MODE_CONNECTOR_TV) {
> +		if (conn_state->connector->connector_type == DRM_MODE_CONNECTOR_TV) {
> 			if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> 				cfg |= JZ_LCD_CFG_MODE_TV_OUT_I;
> 			else
> 				cfg |= JZ_LCD_CFG_MODE_TV_OUT_P;
> 		} else {
> -			switch (*info->bus_formats) {
> +			switch (bridge->bus_cfg.format) {
> 			case MEDIA_BUS_FMT_RGB565_1X16:
> 				cfg |= JZ_LCD_CFG_MODE_GENERIC_16BIT;
> 				break;
> @@ -723,20 +736,29 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
> 	regmap_write(priv->map, JZ_REG_LCD_RGBC, rgbcfg);
> }
> 
> -static int ingenic_drm_encoder_atomic_check(struct drm_encoder *encoder,
> -					    struct drm_crtc_state *crtc_state,
> -					    struct drm_connector_state *conn_state)
> +static int ingenic_drm_bridge_attach(struct drm_bridge *bridge,
> +				     enum drm_bridge_attach_flags flags)
> +{
> +	struct ingenic_drm_bridge *ib = to_ingenic_drm_bridge(bridge->encoder);
> +
> +	return drm_bridge_attach(bridge->encoder, ib->next_bridge,
> +				 &ib->bridge, flags);
> +}
> +
> +static int ingenic_drm_bridge_atomic_check(struct drm_bridge *bridge,
> +					   struct drm_bridge_state *bridge_state,
> +					   struct drm_crtc_state *crtc_state,
> +					   struct drm_connector_state *conn_state)
> {
> -	struct drm_display_info *info = &conn_state->connector->display_info;
> 	struct drm_display_mode *mode = &crtc_state->adjusted_mode;
> +	struct ingenic_drm_bridge *ib = to_ingenic_drm_bridge(bridge->encoder);
> 
> -	if (info->num_bus_formats != 1)
> -		return -EINVAL;
> +	ib->bus_cfg = bridge_state->output_bus_cfg;
> 
> 	if (conn_state->connector->connector_type == DRM_MODE_CONNECTOR_TV)
> 		return 0;
> 
> -	switch (*info->bus_formats) {
> +	switch (bridge_state->output_bus_cfg.format) {
> 	case MEDIA_BUS_FMT_RGB888_3X8:
> 	case MEDIA_BUS_FMT_RGB888_3X8_DELTA:
> 		/*
> @@ -900,8 +922,16 @@ static const struct drm_crtc_helper_funcs ingenic_drm_crtc_helper_funcs = {
> };
> 
> static const struct drm_encoder_helper_funcs ingenic_drm_encoder_helper_funcs = {
> -	.atomic_mode_set	= ingenic_drm_encoder_atomic_mode_set,
> -	.atomic_check		= ingenic_drm_encoder_atomic_check,
> +	.atomic_mode_set        = ingenic_drm_encoder_atomic_mode_set,
> +};
> +
> +static const struct drm_bridge_funcs ingenic_drm_bridge_funcs = {
> +	.attach			= ingenic_drm_bridge_attach,
> +	.atomic_check		= ingenic_drm_bridge_atomic_check,
> +	.atomic_reset		= drm_atomic_helper_bridge_reset,
> +	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
> +	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
> +	.atomic_get_input_bus_fmts = drm_atomic_helper_bridge_propagate_bus_fmt,
> };
> 
> static const struct drm_mode_config_funcs ingenic_drm_mode_config_funcs = {
> @@ -976,7 +1006,9 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
> 	struct drm_plane *primary;
> 	struct drm_bridge *bridge;
> 	struct drm_panel *panel;
> +	struct drm_connector *connector;
> 	struct drm_encoder *encoder;
> +	struct ingenic_drm_bridge *ib;
> 	struct drm_device *drm;
> 	void __iomem *base;
> 	long parent_rate;
> @@ -1154,20 +1186,36 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
> 			bridge = devm_drm_panel_bridge_add_typed(dev, panel,
> 								 DRM_MODE_CONNECTOR_DPI);
> 
> -		encoder = drmm_plain_encoder_alloc(drm, NULL, DRM_MODE_ENCODER_DPI, NULL);
> -		if (IS_ERR(encoder)) {
> -			ret = PTR_ERR(encoder);
> +		ib = drmm_encoder_alloc(drm, struct ingenic_drm_bridge, encoder,
> +					NULL, DRM_MODE_ENCODER_DPI, NULL);
> +		if (IS_ERR(ib)) {
> +			ret = PTR_ERR(ib);
> 			dev_err(dev, "Failed to init encoder: %d\n", ret);
> 			return ret;
> 		}
> 
> -		encoder->possible_crtcs = 1;
> +		encoder = &ib->encoder;
> +		encoder->possible_crtcs = drm_crtc_mask(&priv->crtc);
> 
> 		drm_encoder_helper_add(encoder, &ingenic_drm_encoder_helper_funcs);
> 
> -		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> -		if (ret)
> +		ib->bridge.funcs = &ingenic_drm_bridge_funcs;
> +		ib->next_bridge = bridge;
> +
> +		ret = drm_bridge_attach(encoder, &ib->bridge, NULL,
> +					DRM_BRIDGE_ATTACH_NO_CONNECTOR);

DRM_BRIDGE_ATTACH_NO_CONNECTOR makes it fundamentally incompatible
with synopsys/dw_hdmi.c

That driver checks for DRM_BRIDGE_ATTACH_NO_CONNECTOR being NOT present,
since it wants to register its own connector through dw_hdmi_connector_create().

It does it for a reason: the dw-hdmi is a multi-function driver which does
HDMI and DDC/EDID stuff in a single driver (because I/O registers and power
management seem to be shared).

Since I do not see who could split this into a separate bridge and a connector driver
and test it on multiple SoC platforms (there are at least 3 or 4), I think modifying
the fundamentals of the dw-hdmi architecture just to get CI20 HDMI working is not
our turf.

Therefore the code here should be able to detect if drm_bridge_attach() already
creates and attaches a connector and then skip the code below.

> +		if (ret) {
> +			dev_err(dev, "Unable to attach bridge\n");
> 			return ret;
> +		}
> +
> +		connector = drm_bridge_connector_init(drm, encoder);
> +		if (IS_ERR(connector)) {
> +			dev_err(dev, "Unable to init connector\n");
> +			return PTR_ERR(connector);
> +		}
> +
> +		drm_connector_attach_encoder(connector, encoder);
> 	}
> 
> 	drm_for_each_encoder(encoder, drm) {
> -- 
> 2.33.0

I haven't replaced v2 with v3 in our test tree yet, but will do asap.

BR and thanks,
Nikolaus