drm: add helper to get crtc timings (v5)

We need to get hdisplay and vdisplay in a few places so create a
helper to make our job easier.

Note that drm_crtc_check_viewport() and intel_modeset_pipe_config() were
previously making adjustments for doublescan modes and vscan > 1 modes,
which was incorrect.  Using our new helper fixes this mistake.

v2 (by Matt): Use new stereo doubling function (suggested by Ville)

v3 (by Matt):
 - Add missing kerneldoc (Daniel)
 - Use drm_mode_copy() (Jani)

v4 (by Matt):
 - Drop stereo doubling function again; add 'stereo only' flag
   to drm_mode_set_crtcinfo() instead (Ville)

v5 (by Matt):
 - Note behavioral change in drm_crtc_check_viewport() and
   intel_modeset_pipe_config(). (Ander)
 - Describe new adjustment flags in drm_mode_set_crtcinfo()'s
   kerneldoc. (Ander)

Cc: dri-devel@lists.freedesktop.org
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Reviewed-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -2549,6 +2549,27 @@ int drm_mode_set_config_internal(struct drm_mode_set *set)
 }
 EXPORT_SYMBOL(drm_mode_set_config_internal);
 
+/**
+ * drm_crtc_get_hv_timing - Fetches hdisplay/vdisplay for given mode
+ * @mode: mode to query
+ * @hdisplay: hdisplay value to fill in
+ * @vdisplay: vdisplay value to fill in
+ *
+ * The vdisplay value will be doubled if the specified mode is a stereo mode of
+ * the appropriate layout.
+ */
+void drm_crtc_get_hv_timing(const struct drm_display_mode *mode,
+			    int *hdisplay, int *vdisplay)
+{
+	struct drm_display_mode adjusted;
+
+	drm_mode_copy(&adjusted, mode);
+	drm_mode_set_crtcinfo(&adjusted, CRTC_STEREO_DOUBLE_ONLY);
+	*hdisplay = adjusted.crtc_hdisplay;
+	*vdisplay = adjusted.crtc_vdisplay;
+}
+EXPORT_SYMBOL(drm_crtc_get_hv_timing);
+
 /**
  * drm_crtc_check_viewport - Checks that a framebuffer is big enough for the
  *     CRTC viewport
@@ -2566,16 +2587,7 @@ int drm_crtc_check_viewport(const struct drm_crtc *crtc,
 {
 	int hdisplay, vdisplay;
 
-	hdisplay = mode->hdisplay;
-	vdisplay = mode->vdisplay;
-
-	if (drm_mode_is_stereo(mode)) {
-		struct drm_display_mode adjusted = *mode;
-
-		drm_mode_set_crtcinfo(&adjusted, CRTC_STEREO_DOUBLE);
-		hdisplay = adjusted.crtc_hdisplay;
-		vdisplay = adjusted.crtc_vdisplay;
-	}
+	drm_crtc_get_hv_timing(mode, &hdisplay, &vdisplay);
 
 	if (crtc->invert_dimensions)
 		swap(hdisplay, vdisplay);

drivers/gpu/drm/drm_modes.c

@@ -739,6 +739,8 @@ EXPORT_SYMBOL(drm_mode_vrefresh);
  * - The CRTC_STEREO_DOUBLE flag can be used to compute the timings for
  *   buffers containing two eyes (only adjust the timings when needed, eg. for
  *   "frame packing" or "side by side full").
+ * - The CRTC_NO_DBLSCAN and CRTC_NO_VSCAN flags request that adjustment *not*
+ *   be performed for doublescan and vscan > 1 modes respectively.
  */
 void drm_mode_set_crtcinfo(struct drm_display_mode *p, int adjust_flags)
 {
@@ -765,18 +767,22 @@ void drm_mode_set_crtcinfo(struct drm_display_mode *p, int adjust_flags)
 		}
 	}
 
-	if (p->flags & DRM_MODE_FLAG_DBLSCAN) {
-		p->crtc_vdisplay *= 2;
-		p->crtc_vsync_start *= 2;
-		p->crtc_vsync_end *= 2;
-		p->crtc_vtotal *= 2;
+	if (!(adjust_flags & CRTC_NO_DBLSCAN)) {
+		if (p->flags & DRM_MODE_FLAG_DBLSCAN) {
+			p->crtc_vdisplay *= 2;
+			p->crtc_vsync_start *= 2;
+			p->crtc_vsync_end *= 2;
+			p->crtc_vtotal *= 2;
+		}
 	}
 
-	if (p->vscan > 1) {
-		p->crtc_vdisplay *= p->vscan;
-		p->crtc_vsync_start *= p->vscan;
-		p->crtc_vsync_end *= p->vscan;
-		p->crtc_vtotal *= p->vscan;
+	if (!(adjust_flags & CRTC_NO_VSCAN)) {
+		if (p->vscan > 1) {
+			p->crtc_vdisplay *= p->vscan;
+			p->crtc_vsync_start *= p->vscan;
+			p->crtc_vsync_end *= p->vscan;
+			p->crtc_vtotal *= p->vscan;
+		}
 	}
 
 	if (adjust_flags & CRTC_STEREO_DOUBLE) {

drivers/gpu/drm/i915/intel_display.c

@@ -10322,9 +10322,9 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
 	 * computation to clearly distinguish it from the adjusted mode, which
 	 * can be changed by the connectors in the below retry loop.
 	 */
-	drm_mode_set_crtcinfo(&pipe_config->requested_mode, CRTC_STEREO_DOUBLE);
-	pipe_config->pipe_src_w = pipe_config->requested_mode.crtc_hdisplay;
-	pipe_config->pipe_src_h = pipe_config->requested_mode.crtc_vdisplay;
+	drm_crtc_get_hv_timing(&pipe_config->requested_mode,
+			       &pipe_config->pipe_src_w,
+			       &pipe_config->pipe_src_h);
 
 encoder_retry:
 	/* Ensure the port clock defaults are reset when retrying. */

include/drm/drm_crtc.h

@@ -1161,6 +1161,8 @@ extern int drm_plane_init(struct drm_device *dev,
 extern void drm_plane_cleanup(struct drm_plane *plane);
 extern unsigned int drm_plane_index(struct drm_plane *plane);
 extern void drm_plane_force_disable(struct drm_plane *plane);
+extern void drm_crtc_get_hv_timing(const struct drm_display_mode *mode,
+				   int *hdisplay, int *vdisplay);
 extern int drm_crtc_check_viewport(const struct drm_crtc *crtc,
 				   int x, int y,
 				   const struct drm_display_mode *mode,

include/drm/drm_modes.h

@@ -90,6 +90,9 @@ enum drm_mode_status {
 
 #define CRTC_INTERLACE_HALVE_V	(1 << 0) /* halve V values for interlacing */
 #define CRTC_STEREO_DOUBLE	(1 << 1) /* adjust timings for stereo modes */
+#define CRTC_NO_DBLSCAN		(1 << 2) /* don't adjust doublescan */
+#define CRTC_NO_VSCAN		(1 << 3) /* don't adjust doublescan */
+#define CRTC_STEREO_DOUBLE_ONLY	(CRTC_NO_DBLSCAN | CRTC_NO_VSCAN)
 
 #define DRM_MODE_FLAG_3D_MAX	DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF