drm/ingenic: Properly compute timings when using a 3x8-bit panel

The LCD controller expects timing values in dot-clock ticks, which is 3x
the timing values in pixels when using a 3x8-bit display; but it will
count the display area size in pixels either way. Go figure.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201119155559.14112-3-paul@crapouillou.net

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
index 6b668ce..27512f6 100644 (file)
--- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
@@ -644,6 +644,7 @@ static int ingenic_drm_encoder_atomic_check(struct drm_encoder *encoder,
                                            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;
 
        if (info->num_bus_formats != 1)
                return -EINVAL;
@@ -652,10 +653,22 @@ static int ingenic_drm_encoder_atomic_check(struct drm_encoder *encoder,
                return 0;
 
        switch (*info->bus_formats) {
+       case MEDIA_BUS_FMT_RGB888_3X8:
+               /*
+                * The LCD controller expects timing values in dot-clock ticks,
+                * which is 3x the timing values in pixels when using a 3x8-bit
+                * display; but it will count the display area size in pixels
+                * either way. Go figure.
+                */
+               mode->crtc_clock = mode->clock * 3;
+               mode->crtc_hsync_start = mode->hsync_start * 3 - mode->hdisplay * 2;
+               mode->crtc_hsync_end = mode->hsync_end * 3 - mode->hdisplay * 2;
+               mode->crtc_hdisplay = mode->hdisplay;
+               mode->crtc_htotal = mode->htotal * 3 - mode->hdisplay * 2;
+               return 0;
        case MEDIA_BUS_FMT_RGB565_1X16:
        case MEDIA_BUS_FMT_RGB666_1X18:
        case MEDIA_BUS_FMT_RGB888_1X24:
-       case MEDIA_BUS_FMT_RGB888_3X8:
                return 0;
        default:
                return -EINVAL;