drm/fb-helper: Don't clobber the display palette when fbdev isn't bound

Perform the drm_fb_helper_is_bound() check to avoid clobbering the
display palette of some other KMS client.

While at it, fix up the locking by grabbing all modeset locks for the
duration of the fb_setcmap operation.

v2: Make a note of the locking changes in the commit message

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 7821975..dff2058 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -640,12 +640,19 @@ static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 {
        struct drm_fb_helper *fb_helper = info->par;
+       struct drm_device *dev = fb_helper->dev;
        struct drm_crtc_helper_funcs *crtc_funcs;
        u16 *red, *green, *blue, *transp;
        struct drm_crtc *crtc;
        int i, j, rc = 0;
        int start;
 
+       drm_modeset_lock_all(dev);
+       if (!drm_fb_helper_is_bound(fb_helper)) {
+               drm_modeset_unlock_all(dev);
+               return -EBUSY;
+       }
+
        for (i = 0; i < fb_helper->crtc_count; i++) {
                crtc = fb_helper->crtc_info[i].mode_set.crtc;
                crtc_funcs = crtc->helper_private;
@@ -668,10 +675,12 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 
                        rc = setcolreg(crtc, hred, hgreen, hblue, start++, info);
                        if (rc)
-                               return rc;
+                               goto out;
                }
                crtc_funcs->load_lut(crtc);
        }
+ out:
+       drm_modeset_unlock_all(dev);
        return rc;
 }
 EXPORT_SYMBOL(drm_fb_helper_setcmap);