[PATCH] drm/i915: Check for a change in fb size, and reconfigure the pipe

[Chris Wilson <chris@chris-wilson.co.uk>]

In the slightly unusual case where the pipe is programmed to the same
modeline, but the framebuffer is a new size, we need to resetup the
panel fitter as appropriate and this requires a full modeset. This can
only occur currently as part of the BIOS takeover where there are
slightly different semantics governing how the panel fitter and
framebuffer is programmed relative to the modeline.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f3bec25..de00421 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8114,16 +8114,27 @@ intel_set_config_compute_mode_changes(struct drm_mode_set *set,
 	/* We should be able to check here if the fb has the same properties
 	 * and then just flip_or_move it */
 	if (set->crtc->fb != set->fb) {
+		const struct drm_framebuffer *old = set->crtc->fb;
+		const struct drm_framebuffer *new = set->fb;
+
 		/* If we have no fb then treat it as a full mode set */
-		if (set->crtc->fb == NULL) {
+		if (old == NULL) {
 			DRM_DEBUG_KMS("crtc has no fb, full mode set\n");
 			config->mode_changed = true;
-		} else if (set->fb == NULL) {
+		} else if (new == NULL) {
 			config->mode_changed = true;
-		} else if (set->fb->depth != set->crtc->fb->depth) {
+		/* check for a change in fb size, need to adjust fitting */
+		} else if (new->width != old->width ||
+			   new->height != old->height) {
+			DRM_DEBUG_KMS("fb is changing size (%d, %d) -> (%d, %d), full mode set\n",
+				      old->width, old->height, new->width, new->height);
 			config->mode_changed = true;
-		} else if (set->fb->bits_per_pixel !=
-			   set->crtc->fb->bits_per_pixel) {
+		/* check for a change in fb format, need to reprogram the pipe */
+		} else if (new->depth != old->depth ||
+			   new->bits_per_pixel != old->bits_per_pixel) {
+			DRM_DEBUG_KMS("fb is changing format (%d/%d) -> (%d/%d), full mode set\n",
+				      old->depth, old->bits_per_pixel,
+				      new->depth, new->bits_per_pixel);
 			config->mode_changed = true;
 		} else
 			config->fb_changed = true;
-- 
1.7.10.4