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

From: Paul Cercueil
Date: Thu Sep 23 2021 - 04:49:20 EST

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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

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Previous message: Pavel Skripkin: "Re: [PATCH v9 16/16] staging: r8188eu: remove usb_vendor_req_mutex"
In reply to: H. Nikolaus Schaller: "Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders"
Next in thread: H. Nikolaus Schaller: "Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders"
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