drm_fb_helper: Preserve capability to use atomic kms

Commit 5349ef3127c77075ff70b2014f17ae0fbcaaf199 (drm/fb: fix
FBIOGET/PUT_VSCREENINFO pixel clock handling) changed the logic of
when a pixclock was valid vs invalid.

The atomic kernel mode setting used by the kernel debugger relies upon
the drm_fb_helper_check_var() to always return -EINVAL.  Until a
better solution exists, this behavior will be restored.

CC: David Airlie <airlied@linux.ie>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 6245add3768a..de82e201d682 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -685,7 +685,7 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
         struct drm_framebuffer *fb = fb_helper->fb;
         int depth;
 
-        if (var->pixclock != 0)
+        if (var->pixclock != 0 || in_dbg_master())
                 return -EINVAL;
 
         /* Need to resize the fb object !!! */