From 8c2dcc5f800438d2b4545d21a515e013e6aac484 Mon Sep 17 00:00:00 2001
From: Roman Gilg <subdiff@gmail.com>
Date: Mon, 27 May 2019 22:49:23 +0200
Subject: [PATCH] present: Code cleanup of window to crtc timings update
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Make the code more readable by going through some logical abort
conditions. Also make the function only about updating the crtc
msc value and not about also returning the next target msc.

Signed-off-by: Roman Gilg <subdiff@gmail.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
---
 present/present_scmd.c | 38 ++++++++++++++++++--------------------
 present/present_wnmd.c | 31 +++++++++++++++++--------------
 2 files changed, 35 insertions(+), 34 deletions(-)

diff --git a/present/present_scmd.c b/present/present_scmd.c
index 8bf8fc1d5..cdbacec90 100644
--- a/present/present_scmd.c
+++ b/present/present_scmd.c
@@ -222,30 +222,28 @@ present_queue_vblank(ScreenPtr screen,
     return ret;
 }
 
-static uint64_t
-present_window_to_crtc_msc(WindowPtr window, RRCrtcPtr crtc, uint64_t window_msc, uint64_t new_msc)
+static void
+present_scmd_update_window_crtc(WindowPtr window, RRCrtcPtr crtc, uint64_t new_msc)
 {
-    present_window_priv_ptr     window_priv = present_get_window_priv(window, TRUE);
+    present_window_priv_ptr window_priv = present_get_window_priv(window, TRUE);
+    uint64_t                old_ust, old_msc;
 
-    if (crtc != window_priv->crtc) {
-        uint64_t        old_ust, old_msc;
+    /* Crtc unchanged, no offset. */
+    if (crtc == window_priv->crtc)
+        return;
 
-        if (window_priv->crtc == PresentCrtcNeverSet) {
-            window_priv->msc_offset = 0;
-        } else {
-            /* The old CRTC may have been turned off, in which case
-             * we'll just use whatever previous MSC we'd seen from this CRTC
-             */
-
-            if (present_get_ust_msc(window->drawable.pScreen, window_priv->crtc, &old_ust, &old_msc) != Success)
-                old_msc = window_priv->msc;
-
-            window_priv->msc_offset += new_msc - old_msc;
-        }
+    /* No crtc earlier to offset against, just set the crtc first time. */
+    if (window_priv->crtc == PresentCrtcNeverSet) {
         window_priv->crtc = crtc;
+        return;
     }
 
-    return window_msc + window_priv->msc_offset;
+    /* Crtc may have been turned off, just use whatever previous MSC we'd seen from this CRTC. */
+    if (present_get_ust_msc(window->drawable.pScreen, window_priv->crtc, &old_ust, &old_msc) != Success)
+        old_msc = window_priv->msc;
+
+    window_priv->msc_offset += new_msc - old_msc;
+    window_priv->crtc = crtc;
 }
 
 /*
@@ -682,7 +680,7 @@ present_scmd_pixmap(WindowPtr window,
 
     ret = present_get_ust_msc(screen, target_crtc, &ust, &crtc_msc);
 
-    target_msc = present_window_to_crtc_msc(window, target_crtc, window_msc, crtc_msc);
+    present_scmd_update_window_crtc(window, target_crtc, crtc_msc);
 
     if (ret == Success) {
         /* Stash the current MSC away in case we need it later
@@ -690,7 +688,7 @@ present_scmd_pixmap(WindowPtr window,
         window_priv->msc = crtc_msc;
     }
 
-    target_msc = present_get_target_msc(target_msc,
+    target_msc = present_get_target_msc(window_msc + window_priv->msc_offset,
                                         crtc_msc,
                                         divisor,
                                         remainder,
diff --git a/present/present_wnmd.c b/present/present_wnmd.c
index 91aab985c..8894d99af 100644
--- a/present/present_wnmd.c
+++ b/present/present_wnmd.c
@@ -519,25 +519,28 @@ present_wnmd_queue_vblank(ScreenPtr screen,
     return (*screen_priv->wnmd_info->queue_vblank) (window, crtc, event_id, msc);
 }
 
-static uint64_t
-present_wnmd_window_to_crtc_msc(WindowPtr window, RRCrtcPtr crtc, uint64_t window_msc, uint64_t new_msc)
+static void
+present_wnmd_update_window_crtc(WindowPtr window, RRCrtcPtr crtc, uint64_t new_msc)
 {
     present_window_priv_ptr window_priv = present_get_window_priv(window, TRUE);
 
-    if (crtc != window_priv->crtc) {
-        if (window_priv->crtc == PresentCrtcNeverSet) {
-            window_priv->msc_offset = 0;
-        } else {
-            /* The old CRTC may have been turned off, in which case
-             * we'll just use whatever previous MSC we'd seen from this CRTC
-             */
+    /* Crtc unchanged, no offset. */
+    if (crtc == window_priv->crtc)
+        return;
 
-            window_priv->msc_offset += new_msc - window_priv->msc;
-        }
+    /* No crtc earlier to offset against, just set the crtc. */
+    if (window_priv->crtc == PresentCrtcNeverSet) {
+        window_priv->msc_offset = 0;
         window_priv->crtc = crtc;
+        return;
     }
 
-    return window_msc + window_priv->msc_offset;
+    /* In window-mode the last correct msc-offset is always kept
+     * in window-priv struct because msc is saved per window and
+     * not per crtc as in screen-mode.
+     */
+    window_priv->msc_offset += new_msc - window_priv->msc;
+    window_priv->crtc = crtc;
 }
 
 static int
@@ -574,7 +577,7 @@ present_wnmd_pixmap(WindowPtr window,
 
     ret = present_wnmd_get_ust_msc(screen, window, &ust, &crtc_msc);
 
-    target_msc = present_wnmd_window_to_crtc_msc(window, target_crtc, window_msc, crtc_msc);
+    present_wnmd_update_window_crtc(window, target_crtc, crtc_msc);
 
     if (ret == Success) {
         /* Stash the current MSC away in case we need it later
@@ -582,7 +585,7 @@ present_wnmd_pixmap(WindowPtr window,
         window_priv->msc = crtc_msc;
     }
 
-    target_msc = present_get_target_msc(target_msc,
+    target_msc = present_get_target_msc(window_msc + window_priv->msc_offset,
                                         crtc_msc,
                                         divisor,
                                         remainder,