drm/panel: sitronix-st7789v: add media bus format

Add support for describing the media bus format in the
panel configuration and expose that to userspace. Since
both supported formats (RGB565 and RGB666) are using 6
bits per color also hardcode that information.

Reviewed-by: Michael Riesch <michael.riesch@wolfvision.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230714013756.1546769-11-sre@kernel.org

diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
index aa11a1d..d05d7a9 100644 (file)
--- a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
@@ -10,6 +10,7 @@
 #include <linux/spi/spi.h>
 
 #include <video/mipi_display.h>
+#include <linux/media-bus-format.h>
 
 #include <drm/drm_device.h>
 #include <drm/drm_modes.h>
@@ -110,6 +111,7 @@
 
 struct st7789_panel_info {
        const struct drm_display_mode *mode;
+       u32 bus_format;
 };
 
 struct st7789v {
@@ -169,6 +171,7 @@ static const struct drm_display_mode default_mode = {
 
 static const struct st7789_panel_info default_panel = {
        .mode = &default_mode,
+       .bus_format = MEDIA_BUS_FMT_RGB666_1X18,
 };
 
 static int st7789v_get_modes(struct drm_panel *panel,
@@ -190,8 +193,11 @@ static int st7789v_get_modes(struct drm_panel *panel,
        mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
        drm_mode_probed_add(connector, mode);
 
+       connector->display_info.bpc = 6;
        connector->display_info.width_mm = ctx->info->mode->width_mm;
        connector->display_info.height_mm = ctx->info->mode->height_mm;
+       drm_display_info_set_bus_formats(&connector->display_info,
+                                        &ctx->info->bus_format, 1);
 
        return 1;
 }
@@ -199,8 +205,24 @@ static int st7789v_get_modes(struct drm_panel *panel,
 static int st7789v_prepare(struct drm_panel *panel)
 {
        struct st7789v *ctx = panel_to_st7789v(panel);
+       u8 pixel_fmt;
        int ret;
 
+       switch (ctx->info->bus_format) {
+       case MEDIA_BUS_FMT_RGB666_1X18:
+               pixel_fmt = MIPI_DCS_PIXEL_FMT_18BIT;
+               break;
+       case MEDIA_BUS_FMT_RGB565_1X16:
+               pixel_fmt = MIPI_DCS_PIXEL_FMT_16BIT;
+               break;
+       default:
+               dev_err(panel->dev, "unsupported bus format: %d\n",
+                       ctx->info->bus_format);
+               return -EINVAL;
+       }
+
+       pixel_fmt = (pixel_fmt << 4) | pixel_fmt;
+
        ret = regulator_enable(ctx->power);
        if (ret)
                return ret;
@@ -221,9 +243,7 @@ static int st7789v_prepare(struct drm_panel *panel)
 
        ST7789V_TEST(ret, st7789v_write_command(ctx,
                                                MIPI_DCS_SET_PIXEL_FORMAT));
-       ST7789V_TEST(ret, st7789v_write_data(ctx,
-                                            (MIPI_DCS_PIXEL_FMT_18BIT << 4) |
-                                            (MIPI_DCS_PIXEL_FMT_18BIT)));
+       ST7789V_TEST(ret, st7789v_write_data(ctx, pixel_fmt));
 
        ST7789V_TEST(ret, st7789v_write_command(ctx, ST7789V_PORCTRL_CMD));
        ST7789V_TEST(ret, st7789v_write_data(ctx, 0xc));