Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
 drivers/gpu/drm/fbdevdrm/fbdevdrm_modeset.c | 150 +++++++++++++++++++-
 1 file changed, 149 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/fbdevdrm/fbdevdrm_modeset.c 
b/drivers/gpu/drm/fbdevdrm/fbdevdrm_modeset.c
index 3473b85acbf1..87f56ec76edf 100644
--- a/drivers/gpu/drm/fbdevdrm/fbdevdrm_modeset.c
+++ b/drivers/gpu/drm/fbdevdrm/fbdevdrm_modeset.c
@@ -18,10 +18,18 @@
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_modeset_helper.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 #include <linux/fb.h>
+#include "fbdevdrm_modes.h"
 #include "fbdevdrm_primary.h"
 
+static struct fbdevdrm_modeset* fbdevdrm_modeset_of_crtc(
+       struct drm_crtc *crtc)
+{
+       return container_of(crtc, struct fbdevdrm_modeset, crtc);
+}
+
 /*
  * CRTC
  */
@@ -29,18 +37,124 @@
 static enum drm_mode_status crtc_helper_mode_valid(
        struct drm_crtc *crtc, const struct drm_display_mode *mode)
 {
+       static const unsigned char bits_per_pixel[] = {
+               32, 16, 8, 24, 15
+       };
+
+       struct fbdevdrm_modeset *modeset;
+       struct fb_var_screeninfo fb_var;
+       size_t i;
+       int ret;
+
+       modeset = fbdevdrm_modeset_of_crtc(crtc);
+
+       if (!modeset->fb_info->fbops->fb_check_var)
+               return MODE_OK;
+
+       for (i = 0; i < ARRAY_SIZE(bits_per_pixel); ++i) {
+
+               memcpy(&fb_var, &modeset->fb_info->var, sizeof(fb_var));
+               fbdevdrm_update_fb_var_screeninfo_from_mode(&fb_var, mode);
+               fb_var.bits_per_pixel = bits_per_pixel[i];
+
+               ret = modeset->fb_info->fbops->fb_check_var(&fb_var, 
modeset->fb_info);
+               if (ret)
+                       continue; /* generally not supported */
+               if ((mode->hdisplay != fb_var.xres) ||
+                   (mode->vdisplay != fb_var.yres))
+                       continue; /* unsupported resolution */
+               if (KHZ2PICOS(mode->clock) != fb_var.pixclock)
+                       continue; /* unsupported pixel clock */
+
+               break; /* mode successfully tested */
+       }
+       if (i == ARRAY_SIZE(bits_per_pixel))
+               return MODE_BAD; /* mode is not support */
+
        return MODE_OK;
 }
 
+static int fbdevdrm_update_fb_var_screeninfo_from_crtc(
+       struct fb_var_screeninfo *fb_var, struct drm_crtc* crtc)
+{
+       struct drm_plane *primary = crtc->primary;
+       struct fbdevdrm_modeset *modeset = fbdevdrm_modeset_of_crtc(crtc);
+
+       if (primary && primary->state && primary->state->fb)
+               return fbdevdrm_update_fb_var_screeninfo_from_framebuffer(
+                       fb_var, primary->state->fb,
+                       modeset->fb_info->fix.smem_len);
+
+       fb_var->xres_virtual = fb_var->xres;
+       fb_var->yres_virtual = fb_var->yres;
+       fb_var->bits_per_pixel = modeset->dev->mode_config.preferred_depth;
+
+       return 0;
+}
+
 static bool crtc_helper_mode_fixup(struct drm_crtc *crtc,
                                   const struct drm_display_mode *mode,
                                   struct drm_display_mode *adjusted_mode)
 {
+       struct fbdevdrm_modeset *modeset;
+       struct fb_var_screeninfo fb_var;
+       int ret;
+
+       modeset = fbdevdrm_modeset_of_crtc(crtc);
+
+       if (!modeset->fb_info->fbops->fb_check_var)
+               return true;
+
+       fbdevdrm_init_fb_var_screeninfo_from_mode(&fb_var, mode);
+
+       ret = fbdevdrm_update_fb_var_screeninfo_from_crtc(&fb_var, crtc);
+       if (ret)
+               return true;
+
+       ret = modeset->fb_info->fbops->fb_check_var(&fb_var, modeset->fb_info);
+       if (ret < 0)
+               return false;
+
+       drm_mode_update_from_fb_var_screeninfo(adjusted_mode, &fb_var);
+
        return true;
 }
 
 static void crtc_helper_mode_set_nofb(struct drm_crtc *crtc)
-{ }
+{
+       struct fbdevdrm_modeset *modeset;
+       struct fb_var_screeninfo fb_var;
+       int ret;
+
+       /* As this is atomic mode setting, any function call is not
+        * allowed to fail. If it does, an additional test should be
+        * added to crtc_helper_atomic_check().
+        */
+
+       modeset = fbdevdrm_modeset_of_crtc(crtc);
+
+       memset(&fb_var, 0, sizeof(fb_var));
+       fbdevdrm_update_fb_var_screeninfo_from_mode(&fb_var, 
&crtc->state->adjusted_mode);
+
+       if (crtc->primary && crtc->primary->state && crtc->primary->state->fb) {
+               ret = fbdevdrm_update_fb_var_screeninfo_from_framebuffer(
+                       &fb_var, crtc->primary->state->fb,
+                       modeset->fb_info->fix.smem_len);
+               if (ret)
+                       return;
+       } else {
+               fb_var.xres_virtual = fb_var.xres;
+               fb_var.yres_virtual = fb_var.yres;
+       }
+
+       fb_var.activate = FB_ACTIVATE_NOW;
+
+       ret = fb_set_var(modeset->fb_info, &fb_var);
+       if (ret) {
+               DRM_ERROR("fbdevdrm: fb_set_var() failed: %d\n", ret);
+               return;
+       }
+}
 
 static int crtc_helper_mode_set_base_atomic(struct drm_crtc *crtc,
                                            struct drm_framebuffer *fb,
@@ -53,6 +167,40 @@ static int crtc_helper_mode_set_base_atomic(struct drm_crtc 
*crtc,
 static int crtc_helper_atomic_check(struct drm_crtc *crtc,
                                    struct drm_crtc_state *state)
 {
+       struct fbdevdrm_modeset *modeset;
+       struct fb_videomode fb_mode, fb_var_mode;
+
+       modeset = fbdevdrm_modeset_of_crtc(crtc);
+
+       /* DRM porting notes: when fbcon takes over the console, it regularly
+        * changes the display mode. Where's apparently no way to detect this
+        * directly from fbcon itself. DRM's mode information might therefore
+        * be out of data, after it takes over the display at a later time.
+        * Here, we test the CRTC's current mode with the fbdev state. If they
+        * do not match, we request a mode change from DRM. If you port an
+        * fbdev driver to DRM, you can remove this code section, DRM will
+        * be in full control of the display device and doesn't have to react
+        * to changes from external sources.
+        */
+
+       if (!state->mode_changed && state->adjusted_mode.clock) {
+               fbdevdrm_init_fb_videomode_from_mode(&fb_mode, 
&state->adjusted_mode);
+               fb_var_to_videomode(&fb_var_mode, &modeset->fb_info->var);
+               if (!fb_mode_is_equal(&fb_mode, &fb_var_mode))
+                       state->mode_changed = true;
+       }
+
+       /* TODO: The vblank interupt is currently not supported. We set
+        * the corresponding flag as a workaround. Some fbdev drivers
+        * support FBIO_WAITFORVSYNC, which we might use for querying
+        * vblanks.
+        *
+        * DRM porting notes: if you're porting an fbdev driver to DRM,
+        * remove this line and instead signal a vblank event from the
+        * interupt handler.
+        */
+       state->no_vblank = true;
+
        return 0;
 }
 
-- 
2.21.0

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