Components further up in the chain might ask us for supported formats.

Without this MEDIA_BUS_FMT_FIXED is assumed which then breaks display output with mxsfb since it can't determine a proper bus format.

We handle the bus formats that correspond to the DSI formats the bridge can potentially output (see chapter 13.6 of the i.MX 8MQ reference manual) - which matches what xsfb can input.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Signed-off-by: Guido Günther agx@sigxcpu.org --- drivers/gpu/drm/bridge/nwl-dsi.c | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c index a251cc1f088f..27c80d36846b 100644 --- a/drivers/gpu/drm/bridge/nwl-dsi.c +++ b/drivers/gpu/drm/bridge/nwl-dsi.c @@ -1234,6 +1234,40 @@ static void nwl_dsi_bridge_detach(struct drm_bridge *bridge) drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0); }

+static u32 *nwl_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + u32 output_fmt, + unsigned int *num_input_fmts) +{ + u32 *input_fmts, input_fmt; + + *num_input_fmts = 0; + + switch (output_fmt) { + /* If MEDIA_BUS_FMT_FIXED is tested, return default bus format */ + case MEDIA_BUS_FMT_FIXED: + input_fmt = MEDIA_BUS_FMT_RGB888_1X24; + break; + case MEDIA_BUS_FMT_RGB888_1X24: + case MEDIA_BUS_FMT_RGB666_1X18: + case MEDIA_BUS_FMT_RGB565_1X16: + input_fmt = output_fmt; + break; + default: + return NULL; + } + + input_fmts = kcalloc(1, sizeof(*input_fmts), GFP_KERNEL); + if (!input_fmts) + return NULL; + input_fmts[0] = input_fmt; + *num_input_fmts = 1; + + return input_fmts; +} + static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = { .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state, .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state, @@ -1241,6 +1275,7 @@ static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = { .atomic_check = nwl_dsi_bridge_atomic_check, .atomic_enable = nwl_dsi_bridge_atomic_enable, .atomic_disable = nwl_dsi_bridge_atomic_disable, + .atomic_get_input_bus_fmts = nwl_bridge_atomic_get_input_bus_fmts, .mode_set = nwl_dsi_bridge_mode_set, .mode_valid = nwl_dsi_bridge_mode_valid, .attach = nwl_dsi_bridge_attach,

This allows the DSI bridge to detect the correct bus format. We currently only support MEDIA_BUS_FMT_RGB888_1X24.

Signed-off-by: Guido Günther agx@sigxcpu.org --- drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c | 9 +++++++++ 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c index f0e9bce23c41..d6bcf1045255 100644 --- a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c +++ b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c @@ -8,6 +8,7 @@ #include <linux/backlight.h> #include <linux/delay.h> #include <linux/gpio/consumer.h> +#include <linux/media-bus-format.h> #include <linux/module.h> #include <linux/of_device.h> #include <linux/regulator/consumer.h> @@ -232,6 +233,10 @@ static const struct drm_display_mode default_mode_ys = { .height_mm = 130, };

+static const u32 mantix_bus_formats[] = { + MEDIA_BUS_FMT_RGB888_1X24, +}; + static int mantix_get_modes(struct drm_panel *panel, struct drm_connector *connector) { @@ -253,6 +258,10 @@ static int mantix_get_modes(struct drm_panel *panel, connector->display_info.height_mm = mode->height_mm; drm_mode_probed_add(connector, mode);

+ drm_display_info_set_bus_formats(&connector->display_info, + mantix_bus_formats, + ARRAY_SIZE(mantix_bus_formats)); + return 1; }

media-bus-formats.h has them in hexadecimal as well so matching with that file saves one conversion when debugging.

Signed-off-by: Guido Günther agx@sigxcpu.org --- drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c index af6c620adf6e..d6abd2077114 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c @@ -89,7 +89,7 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb, ctrl |= CTRL_BUS_WIDTH_24; break; default: - dev_err(drm->dev, "Unknown media bus format %d\n", bus_format); + dev_err(drm->dev, "Unknown media bus format 0x%x\n", bus_format); break; }

If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in that case.

This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Reported-by: Martin Kepplinger martink@posteo.de Signed-off-by: Guido Günther agx@sigxcpu.org --- drivers/gpu/drm/mxsfb/mxsfb_kms.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c index d6abd2077114..e3fbb8b58d5d 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c @@ -369,6 +369,12 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc, drm_atomic_get_new_bridge_state(state, mxsfb->bridge); bus_format = bridge_state->input_bus_cfg.format; + if (bus_format == MEDIA_BUS_FMT_FIXED) { + dev_warn_once(drm->dev, + "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n" + "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n"); + bus_format = MEDIA_BUS_FMT_RGB888_1X24; + } }

/* If there is no bridge, use bus format from connector */