drm/imx: imx-ldb: allow to determine bus format from the connected panel

This patch makes the fsl,data-width and fsl,data-mapping device tree
properties optional if a panel is connected to the ldb output port
via the of_graph bindings. The data mapping is determined from the
display_info.bus_format field provided by the panel.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

1 files changed, 63 insertions, 53 deletions

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index 544282bd4f7f..abacc8f67469 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -63,6 +63,7 @@ struct imx_ldb_channel {
         int edid_len;
         struct drm_display_mode mode;
         int mode_valid;
+        int bus_format;
 };
 
 struct bus_mux {
@@ -96,7 +97,11 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
 
         if (imx_ldb_ch->panel && imx_ldb_ch->panel->funcs &&
             imx_ldb_ch->panel->funcs->get_modes) {
+                struct drm_display_info *di = &connector->display_info;
+
                 num_modes = imx_ldb_ch->panel->funcs->get_modes(imx_ldb_ch->panel);
+                if (!imx_ldb_ch->bus_format && di->num_bus_formats)
+                        imx_ldb_ch->bus_format = di->bus_formats[0];
                 if (num_modes > 0)
                         return num_modes;
         }
@@ -173,21 +178,33 @@ static void imx_ldb_encoder_prepare(struct drm_encoder *encoder)
 {
         struct imx_ldb_channel *imx_ldb_ch = enc_to_imx_ldb_ch(encoder);
         struct imx_ldb *ldb = imx_ldb_ch->ldb;
+        int dual = ldb->ldb_ctrl & LDB_SPLIT_MODE_EN;
         u32 bus_format;
 
-        switch (imx_ldb_ch->chno) {
-        case 0:
-                bus_format = (ldb->ldb_ctrl & LDB_DATA_WIDTH_CH0_24) ?
-                        MEDIA_BUS_FMT_RGB888_1X24 : MEDIA_BUS_FMT_RGB666_1X18;
+        switch (imx_ldb_ch->bus_format) {
+        default:
+                dev_warn(ldb->dev,
+                         "could not determine data mapping, default to 18-bit \"spwg\"\n");
+                /* fallthrough */
+        case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+                bus_format = MEDIA_BUS_FMT_RGB666_1X18;
                 break;
-        case 1:
-                bus_format = (ldb->ldb_ctrl & LDB_DATA_WIDTH_CH1_24) ?
-                        MEDIA_BUS_FMT_RGB888_1X24 : MEDIA_BUS_FMT_RGB666_1X18;
+        case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+                bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+                if (imx_ldb_ch->chno == 0 || dual)
+                        ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH0_24;
+                if (imx_ldb_ch->chno == 1 || dual)
+                        ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH1_24;
                 break;
-        default:
-                dev_err(ldb->dev, "unable to config di%d panel format\n",
-                        imx_ldb_ch->chno);
+        case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
                 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+                if (imx_ldb_ch->chno == 0 || dual)
+                        ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH0_24 |
+                                         LDB_BIT_MAP_CH0_JEIDA;
+                if (imx_ldb_ch->chno == 1 || dual)
+                        ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH1_24 |
+                                         LDB_BIT_MAP_CH1_JEIDA;
+                break;
         }
 
         imx_drm_set_bus_format(encoder, bus_format);
@@ -426,25 +443,39 @@ enum {
         LVDS_BIT_MAP_JEIDA
 };
 
-static const char * const imx_ldb_bit_mappings[] = {
-        [LVDS_BIT_MAP_SPWG]  = "spwg",
-        [LVDS_BIT_MAP_JEIDA] = "jeida",
+struct imx_ldb_bit_mapping {
+        u32 bus_format;
+        u32 datawidth;
+        const char * const mapping;
 };
 
-static const int of_get_data_mapping(struct device_node *np)
+static const struct imx_ldb_bit_mapping imx_ldb_bit_mappings[] = {
+        { MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,  18, "spwg" },
+        { MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,  24, "spwg" },
+        { MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA, 24, "jeida" },
+};
+
+static u32 of_get_bus_format(struct device *dev, struct device_node *np)
 {
         const char *bm;
+        u32 datawidth = 0;
         int ret, i;
 
         ret = of_property_read_string(np, "fsl,data-mapping", &bm);
         if (ret < 0)
                 return ret;
 
-        for (i = 0; i < ARRAY_SIZE(imx_ldb_bit_mappings); i++)
-                if (!strcasecmp(bm, imx_ldb_bit_mappings[i]))
-                        return i;
+        of_property_read_u32(np, "fsl,data-width", &datawidth);
+
+        for (i = 0; i < ARRAY_SIZE(imx_ldb_bit_mappings); i++) {
+                if (!strcasecmp(bm, imx_ldb_bit_mappings[i].mapping) &&
+                    datawidth == imx_ldb_bit_mappings[i].datawidth)
+                        return imx_ldb_bit_mappings[i].bus_format;
+        }
+
+        dev_err(dev, "invalid data mapping: %d-bit \"%s\"\n", datawidth, bm);
 
-        return -EINVAL;
+        return -ENOENT;
 }
 
 static struct bus_mux imx6q_lvds_mux[2] = {
@@ -481,8 +512,6 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
         struct device_node *child;
         const u8 *edidp;
         struct imx_ldb *imx_ldb;
-        int datawidth;
-        int mapping;
         int dual;
         int ret;
         int i;
@@ -583,39 +612,20 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
                                 channel->mode_valid = 1;
                 }
 
-                ret = of_property_read_u32(child, "fsl,data-width", &datawidth);
-                if (ret)
-                        datawidth = 0;
-                else if (datawidth != 18 && datawidth != 24)
-                        return -EINVAL;
-
-                mapping = of_get_data_mapping(child);
-                switch (mapping) {
-                case LVDS_BIT_MAP_SPWG:
-                        if (datawidth == 24) {
-                                if (i == 0 || dual)
-                                        imx_ldb->ldb_ctrl |=
-                                                LDB_DATA_WIDTH_CH0_24;
-                                if (i == 1 || dual)
-                                        imx_ldb->ldb_ctrl |=
-                                                LDB_DATA_WIDTH_CH1_24;
-                        }
-                        break;
-                case LVDS_BIT_MAP_JEIDA:
-                        if (datawidth == 18) {
-                                dev_err(dev, "JEIDA standard only supported in 24 bit\n");
-                                return -EINVAL;
-                        }
-                        if (i == 0 || dual)
-                                imx_ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH0_24 |
-                                        LDB_BIT_MAP_CH0_JEIDA;
-                        if (i == 1 || dual)
-                                imx_ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH1_24 |
-                                        LDB_BIT_MAP_CH1_JEIDA;
-                        break;
-                default:
-                        dev_err(dev, "data mapping not specified or invalid\n");
-                        return -EINVAL;
+                channel->bus_format = of_get_bus_format(dev, child);
+                if (channel->bus_format == -EINVAL) {
+                        /*
+                         * If no bus format was specified in the device tree,
+                         * we can still get it from the connected panel later.
+                         */
+                        if (channel->panel && channel->panel->funcs &&
+                            channel->panel->funcs->get_modes)
+                                channel->bus_format = 0;
+                }
+                if (channel->bus_format < 0) {
+                        dev_err(dev, "could not determine data mapping: %d\n",
+                                channel->bus_format);
+                        return channel->bus_format;
                 }
 
                 ret = imx_ldb_register(drm, channel);