[PATCH v2 16/16] drm/ast: Only look up VBIOS mode on full modesets

[Thomas Zimmermann]

Only look up the VBIOS mode during atomic_check if the display mode
changes. For page flips, the previous settings still apply. Avoids the
runtime overhead of looking up the VBIOS mode on each page flip.

Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
Reviewed-by: Jocelyn Falempe <jfale...@redhat.com>
---
 drivers/gpu/drm/ast/ast_mode.c | 52 ++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index a93994b00f40a..bd781293b6d97 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -996,32 +996,34 @@ static int ast_crtc_helper_atomic_check(struct drm_crtc 
*crtc,
        }
 
        /*
-        * Find the VBIOS mode and adjust the DRM display mode accordingly.
+        * Find the VBIOS mode and adjust the DRM display mode accordingly
+        * if a full modeset is required. Otherwise keep the existing values.
         */
-
-       vmode = ast_vbios_find_mode(ast, &crtc_state->mode);
-       if (!vmode)
-               return -EINVAL;
-       ast_state->vmode = vmode;
-
-       if (vmode->flags & HBorder)
-               hborder = 8;
-       if (vmode->flags & VBorder)
-               vborder = 8;
-
-       adjusted_mode->crtc_hdisplay = vmode->hde;
-       adjusted_mode->crtc_hblank_start = vmode->hde + hborder;
-       adjusted_mode->crtc_hblank_end = vmode->ht - hborder;
-       adjusted_mode->crtc_hsync_start = vmode->hde + hborder + vmode->hfp;
-       adjusted_mode->crtc_hsync_end = vmode->hde + hborder + vmode->hfp + 
vmode->hsync;
-       adjusted_mode->crtc_htotal = vmode->ht;
-
-       adjusted_mode->crtc_vdisplay = vmode->vde;
-       adjusted_mode->crtc_vblank_start = vmode->vde + vborder;
-       adjusted_mode->crtc_vblank_end = vmode->vt - vborder;
-       adjusted_mode->crtc_vsync_start = vmode->vde + vborder + vmode->vfp;
-       adjusted_mode->crtc_vsync_end = vmode->vde + vborder + vmode->vfp + 
vmode->vsync;
-       adjusted_mode->crtc_vtotal = vmode->vt;
+       if (drm_atomic_crtc_needs_modeset(crtc_state)) {
+               vmode = ast_vbios_find_mode(ast, &crtc_state->mode);
+               if (!vmode)
+                       return -EINVAL;
+               ast_state->vmode = vmode;
+
+               if (vmode->flags & HBorder)
+                       hborder = 8;
+               if (vmode->flags & VBorder)
+                       vborder = 8;
+
+               adjusted_mode->crtc_hdisplay = vmode->hde;
+               adjusted_mode->crtc_hblank_start = vmode->hde + hborder;
+               adjusted_mode->crtc_hblank_end = vmode->ht - hborder;
+               adjusted_mode->crtc_hsync_start = vmode->hde + hborder + 
vmode->hfp;
+               adjusted_mode->crtc_hsync_end = vmode->hde + hborder + 
vmode->hfp + vmode->hsync;
+               adjusted_mode->crtc_htotal = vmode->ht;
+
+               adjusted_mode->crtc_vdisplay = vmode->vde;
+               adjusted_mode->crtc_vblank_start = vmode->vde + vborder;
+               adjusted_mode->crtc_vblank_end = vmode->vt - vborder;
+               adjusted_mode->crtc_vsync_start = vmode->vde + vborder + 
vmode->vfp;
+               adjusted_mode->crtc_vsync_end = vmode->vde + vborder + 
vmode->vfp + vmode->vsync;
+               adjusted_mode->crtc_vtotal = vmode->vt;
+       }
 
        return 0;
 }
-- 
2.48.1