drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC

Implement legacy framebuffer ioctl FBIO_WAITFORVSYNC in the generic
framebuffer emulation driver. Legacy framebuffer users like non kms/drm
based OpenGL(ES)/EGL implementations may require the ioctl to
synchronize drawing or buffer flip for double buffering. It is tested on
the i.MX6.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2c92ccf..45fde2f 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1245,6 +1245,74 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 EXPORT_SYMBOL(drm_fb_helper_setcmap);
 
 /**
+ * drm_fb_helper_ioctl - legacy ioctl implementation
+ * @info: fbdev registered by the helper
+ * @cmd: ioctl command
+ * @arg: ioctl argument
+ *
+ * A helper to implement the standard fbdev ioctl. Only
+ * FBIO_WAITFORVSYNC is implemented for now.
+ */
+int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
+                       unsigned long arg)
+{
+       struct drm_fb_helper *fb_helper = info->par;
+       struct drm_device *dev = fb_helper->dev;
+       struct drm_mode_set *mode_set;
+       struct drm_crtc *crtc;
+       int ret = 0;
+
+       mutex_lock(&dev->mode_config.mutex);
+       if (!drm_fb_helper_is_bound(fb_helper)) {
+               ret = -EBUSY;
+               goto unlock;
+       }
+
+       switch (cmd) {
+       case FBIO_WAITFORVSYNC:
+               /*
+                * Only consider the first CRTC.
+                *
+                * This ioctl is supposed to take the CRTC number as
+                * an argument, but in fbdev times, what that number
+                * was supposed to be was quite unclear, different
+                * drivers were passing that argument differently
+                * (some by reference, some by value), and most of the
+                * userspace applications were just hardcoding 0 as an
+                * argument.
+                *
+                * The first CRTC should be the integrated panel on
+                * most drivers, so this is the best choice we can
+                * make. If we're not smart enough here, one should
+                * just consider switch the userspace to KMS.
+                */
+               mode_set = &fb_helper->crtc_info[0].mode_set;
+               crtc = mode_set->crtc;
+
+               /*
+                * Only wait for a vblank event if the CRTC is
+                * enabled, otherwise just don't do anythintg,
+                * not even report an error.
+                */
+               ret = drm_crtc_vblank_get(crtc);
+               if (!ret) {
+                       drm_crtc_wait_one_vblank(crtc);
+                       drm_crtc_vblank_put(crtc);
+               }
+
+               ret = 0;
+               goto unlock;
+       default:
+               ret = -ENOTTY;
+       }
+
+unlock:
+       mutex_unlock(&dev->mode_config.mutex);
+       return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_ioctl);
+
+/**
  * drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
  * @var: screeninfo to check
  * @info: fbdev registered by the helper

diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 339226d..119e5e4 100644 (file)
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -230,7 +230,8 @@ struct drm_fb_helper {
        .fb_blank       = drm_fb_helper_blank, \
        .fb_pan_display = drm_fb_helper_pan_display, \
        .fb_debug_enter = drm_fb_helper_debug_enter, \
-       .fb_debug_leave = drm_fb_helper_debug_leave
+       .fb_debug_leave = drm_fb_helper_debug_leave, \
+       .fb_ioctl       = drm_fb_helper_ioctl
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
 void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
@@ -284,6 +285,9 @@ void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
 
 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
 
+int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
+                       unsigned long arg);
+
 int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
 int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel);
 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper);
@@ -371,6 +375,12 @@ static inline int drm_fb_helper_setcmap(struct fb_cmap *cmap,
        return 0;
 }
 
+static inline int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
+                                     unsigned long arg)
+{
+       return 0;
+}
+
 static inline void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
 {
 }