drm/panel: simple: Add display timing support

The simple panel driver's ->get_modes() implementation calculates the
display mode list from the typical timings and the ->get_timings()
implementation returns the timings to the connected encoder for mode
validation and fixup.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
[treding@nvidia.com: select VIDEOMODE_HELPERS]
Signed-off-by: Thierry Reding <treding@nvidia.com>

2 files changed, 43 insertions, 0 deletions

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index d84583776d50..6d64c7bb908b 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -11,6 +11,7 @@ config DRM_PANEL_SIMPLE
         tristate "support for simple panels"
         depends on OF
         depends on BACKLIGHT_CLASS_DEVICE
+        select VIDEOMODE_HELPERS
         help
           DRM panel driver for dumb panels that need at most a regulator and
           a GPIO to be powered up. Optionally a backlight can be attached so
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index d9491bc8f9a4..be2c4c85ea83 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -33,9 +33,14 @@
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_panel.h>
 
+#include <video/display_timing.h>
+#include <video/videomode.h>
+
 struct panel_desc {
         const struct drm_display_mode *modes;
         unsigned int num_modes;
+        const struct display_timing *timings;
+        unsigned int num_timings;
 
         unsigned int bpc;
 
@@ -94,6 +99,25 @@ static int panel_simple_get_fixed_modes(struct panel_simple *panel)
         if (!panel->desc)
                 return 0;
 
+        for (i = 0; i < panel->desc->num_timings; i++) {
+                const struct display_timing *dt = &panel->desc->timings[i];
+                struct videomode vm;
+
+                videomode_from_timing(dt, &vm);
+                mode = drm_mode_create(drm);
+                if (!mode) {
+                        dev_err(drm->dev, "failed to add mode %ux%u\n",
+                                dt->hactive.typ, dt->vactive.typ);
+                        continue;
+                }
+
+                drm_display_mode_from_videomode(&vm, mode);
+                drm_mode_set_name(mode);
+
+                drm_mode_probed_add(connector, mode);
+                num++;
+        }
+
         for (i = 0; i < panel->desc->num_modes; i++) {
                 const struct drm_display_mode *m = &panel->desc->modes[i];
 
@@ -226,12 +250,30 @@ static int panel_simple_get_modes(struct drm_panel *panel)
         return num;
 }
 
+static int panel_simple_get_timings(struct drm_panel *panel,
+                                    unsigned int num_timings,
+                                    struct display_timing *timings)
+{
+        struct panel_simple *p = to_panel_simple(panel);
+        unsigned int i;
+
+        if (p->desc->num_timings < num_timings)
+                num_timings = p->desc->num_timings;
+
+        if (timings)
+                for (i = 0; i < num_timings; i++)
+                        timings[i] = p->desc->timings[i];
+
+        return p->desc->num_timings;
+}
+
 static const struct drm_panel_funcs panel_simple_funcs = {
         .disable = panel_simple_disable,
         .unprepare = panel_simple_unprepare,
         .prepare = panel_simple_prepare,
         .enable = panel_simple_enable,
         .get_modes = panel_simple_get_modes,
+        .get_timings = panel_simple_get_timings,
 };
 
 static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)