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

[Paul Cercueil <paul@xxxxxxxxxxxxxxx>]

Hi Nikolaus,

Le jeu., sept. 23 2021 at 07:52:08 +0200, H. Nikolaus Schaller 
<hns@xxxxxxxxxxxxx> a écrit :
> 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.

I think the SoC can output YCbCr as well, but I never tried to use it.

> 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).

The IT66121 driver does all of that too, and does not need 
DRM_BRIDGE_ATTACH_NO_CONNECTOR. The drm_bridge_funcs struct has 
callbacks to handle cable detection and DDC stuff.

> 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.

You could have a field in the dw-hdmi pdata structure, that would 
instruct the driver whether or not it should use the new API. Ugly, I 
know, and would probably duplicate a lot of code, but that would allow 
other drivers to be updated at a later date.

> 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.

Not that easy, unfortunately. On one side we have dw-hdmi which checks 
that DRM_BRIDGE_ATTACH_NO_CONNECTOR is not set, and on the other side 
we have other drivers like the IT66121 which will fail if this flag is 
not set.

Cheers,
-Paul

> >  +		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