drm/i915: Extract intel_crtc_scanline_offset()

Pull the scanline_offset calculation into its own function. Might
have further use for this later with DSB scanline waits.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230310235828.17439-4-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 48bf3923af11c602b3d601fcb7416ede434329ca..f8bf9810527de8a1e10d542c8f6459233cc8807b 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -441,6 +441,53 @@ void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc)
        wait_for_pipe_scanline_moving(crtc, true);
 }
 
+static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
+{
+       struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+       const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+
+       /*
+        * The scanline counter increments at the leading edge of hsync.
+        *
+        * On most platforms it starts counting from vtotal-1 on the
+        * first active line. That means the scanline counter value is
+        * always one less than what we would expect. Ie. just after
+        * start of vblank, which also occurs at start of hsync (on the
+        * last active line), the scanline counter will read vblank_start-1.
+        *
+        * On gen2 the scanline counter starts counting from 1 instead
+        * of vtotal-1, so we have to subtract one (or rather add vtotal-1
+        * to keep the value positive), instead of adding one.
+        *
+        * On HSW+ the behaviour of the scanline counter depends on the output
+        * type. For DP ports it behaves like most other platforms, but on HDMI
+        * there's an extra 1 line difference. So we need to add two instead of
+        * one to the value.
+        *
+        * On VLV/CHV DSI the scanline counter would appear to increment
+        * approx. 1/3 of a scanline before start of vblank. Unfortunately
+        * that means we can't tell whether we're in vblank or not while
+        * we're on that particular line. We must still set scanline_offset
+        * to 1 so that the vblank timestamps come out correct when we query
+        * the scanline counter from within the vblank interrupt handler.
+        * However if queried just before the start of vblank we'll get an
+        * answer that's slightly in the future.
+        */
+       if (DISPLAY_VER(i915) == 2) {
+               int vtotal;
+
+               vtotal = adjusted_mode->crtc_vtotal;
+               if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
+                       vtotal /= 2;
+
+               return vtotal - 1;
+       } else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
+               return 2;
+       } else {
+               return 1;
+       }
+}
+
 void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
 {
        struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
@@ -479,47 +526,7 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
 
        crtc->mode_flags = crtc_state->mode_flags;
 
-       /*
-        * The scanline counter increments at the leading edge of hsync.
-        *
-        * On most platforms it starts counting from vtotal-1 on the
-        * first active line. That means the scanline counter value is
-        * always one less than what we would expect. Ie. just after
-        * start of vblank, which also occurs at start of hsync (on the
-        * last active line), the scanline counter will read vblank_start-1.
-        *
-        * On gen2 the scanline counter starts counting from 1 instead
-        * of vtotal-1, so we have to subtract one (or rather add vtotal-1
-        * to keep the value positive), instead of adding one.
-        *
-        * On HSW+ the behaviour of the scanline counter depends on the output
-        * type. For DP ports it behaves like most other platforms, but on HDMI
-        * there's an extra 1 line difference. So we need to add two instead of
-        * one to the value.
-        *
-        * On VLV/CHV DSI the scanline counter would appear to increment
-        * approx. 1/3 of a scanline before start of vblank. Unfortunately
-        * that means we can't tell whether we're in vblank or not while
-        * we're on that particular line. We must still set scanline_offset
-        * to 1 so that the vblank timestamps come out correct when we query
-        * the scanline counter from within the vblank interrupt handler.
-        * However if queried just before the start of vblank we'll get an
-        * answer that's slightly in the future.
-        */
-       if (DISPLAY_VER(i915) == 2) {
-               int vtotal;
-
-               vtotal = adjusted_mode.crtc_vtotal;
-               if (adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE)
-                       vtotal /= 2;
-
-               crtc->scanline_offset = vtotal - 1;
-       } else if (HAS_DDI(i915) &&
-                  intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
-               crtc->scanline_offset = 2;
-       } else {
-               crtc->scanline_offset = 1;
-       }
+       crtc->scanline_offset = intel_crtc_scanline_offset(crtc_state);
 
        spin_unlock(&i915->uncore.lock);
        spin_unlock_irqrestore(&i915->drm.vblank_time_lock, irqflags);