sna: Use dirtyfb for fallback direct rendering

The preferred solution when direct rendering is too costly is to render
into the backbuffer and flip. However, if the user insists, we need to
tell the kernel when to flush the scanout due to direct rendering.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/sna/sna_driver.c b/src/sna/sna_driver.c
index 14ec2f6a..b2455941 100644
--- a/src/sna/sna_driver.c
+++ b/src/sna/sna_driver.c
@@ -461,13 +461,13 @@ static bool enable_tear_free(struct sna *sna)
 	return ENABLE_TEAR_FREE;
 }
 
-static void setup_tear_free(struct sna *sna)
+static bool setup_tear_free(struct sna *sna)
 {
 	MessageType from;
 	Bool enable;
 
 	if (sna->flags & SNA_LINEAR_FB)
-		return;
+		return false;
 
 	if ((sna->flags & SNA_HAS_FLIP) == 0) {
 		from = X_PROBED;
@@ -486,6 +486,7 @@ static void setup_tear_free(struct sna *sna)
 done:
 	xf86DrvMsg(sna->scrn->scrnIndex, from, "TearFree %sabled\n",
 		   sna->flags & SNA_TEAR_FREE ? "en" : "dis");
+	return sna->flags & SNA_TEAR_FREE;
 }
 
 /**
@@ -653,7 +654,8 @@ static Bool sna_pre_init(ScrnInfoPtr scrn, int probe)
 	}
 	scrn->currentMode = scrn->modes;
 
-	setup_tear_free(sna);
+	if (!setup_tear_free(sna) && sna_mode_wants_tear_free(sna))
+		sna->kgem.needs_dirtyfb = sna->kgem.has_dirtyfb;
 
 	xf86SetGamma(scrn, zeros);
 	xf86SetDpi(scrn, 0, 0);