[PATCH v2] drm/meson: Fix atomic mode switching regression

[Neil Armstrong <narmstrong@baylibre.com>]

Since commit 2bcd3ecab773 when switching mode from X11 (ubuntu mate for
example) the display gets blurry, looking like an invalid framebuffer width.

This commit fixed atomic crtc modesetting in a totally wrong way and
introduced a local unnecessary ->enabled crtc state.

This commit reverts the crctc _begin() and _enable() changes and simply
adds drm_atomic_helper_commit_tail_rpm as helper.

Reported-by: Tony McKahan <tonymckahan@gmail.com>
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Fixes: 2bcd3ecab773 ("drm/meson: Fixes for drm_crtc_vblank_on/off support")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/gpu/drm/meson/meson_crtc.c | 23 ++---------------------
 drivers/gpu/drm/meson/meson_drv.c  |  6 ++++++
 2 files changed, 8 insertions(+), 21 deletions(-)

Changes since v1:
- drop the unecessary local ->enabled logic
- use drm_atomic_helper_commit_tail_rpm as atomic_commit_tail helper

diff --git a/drivers/gpu/drm/meson/meson_crtc.c b/drivers/gpu/drm/meson/meson_crtc.c
index 75d97f1b2e8f..4f5c67f70c4d 100644
--- a/drivers/gpu/drm/meson/meson_crtc.c
+++ b/drivers/gpu/drm/meson/meson_crtc.c
@@ -46,7 +46,6 @@ struct meson_crtc {
 	struct drm_crtc base;
 	struct drm_pending_vblank_event *event;
 	struct meson_drm *priv;
-	bool enabled;
 };
 #define to_meson_crtc(x) container_of(x, struct meson_crtc, base)
 
@@ -82,7 +81,8 @@ static const struct drm_crtc_funcs meson_crtc_funcs = {
 
 };
 
-static void meson_crtc_enable(struct drm_crtc *crtc)
+static void meson_crtc_atomic_enable(struct drm_crtc *crtc,
+				     struct drm_crtc_state *old_state)
 {
 	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
 	struct drm_crtc_state *crtc_state = crtc->state;
@@ -108,20 +108,6 @@ static void meson_crtc_enable(struct drm_crtc *crtc)
 
 	drm_crtc_vblank_on(crtc);
 
-	meson_crtc->enabled = true;
-}
-
-static void meson_crtc_atomic_enable(struct drm_crtc *crtc,
-				     struct drm_crtc_state *old_state)
-{
-	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
-	struct meson_drm *priv = meson_crtc->priv;
-
-	DRM_DEBUG_DRIVER("\n");
-
-	if (!meson_crtc->enabled)
-		meson_crtc_enable(crtc);
-
 	priv->viu.osd1_enabled = true;
 }
 
@@ -153,8 +139,6 @@ static void meson_crtc_atomic_disable(struct drm_crtc *crtc,
 
 		crtc->state->event = NULL;
 	}
-
-	meson_crtc->enabled = false;
 }
 
 static void meson_crtc_atomic_begin(struct drm_crtc *crtc,
@@ -163,9 +147,6 @@ static void meson_crtc_atomic_begin(struct drm_crtc *crtc,
 	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
 	unsigned long flags;
 
-	if (crtc->state->enable && !meson_crtc->enabled)
-		meson_crtc_enable(crtc);
-
 	if (crtc->state->event) {
 		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
 
diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
index 3ee4d4a4ecba..a74d861ddceb 100644
--- a/drivers/gpu/drm/meson/meson_drv.c
+++ b/drivers/gpu/drm/meson/meson_drv.c
@@ -75,6 +75,11 @@ static const struct drm_mode_config_funcs meson_mode_config_funcs = {
 	.fb_create           = drm_gem_fb_create,
 };
 
+
+static const struct drm_mode_config_helper_funcs meson_mode_config_helpers = {
+	.atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
+};
+
 static irqreturn_t meson_irq(int irq, void *arg)
 {
 	struct drm_device *dev = arg;
@@ -266,6 +271,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
 	drm->mode_config.max_width = 3840;
 	drm->mode_config.max_height = 2160;
 	drm->mode_config.funcs = &meson_mode_config_funcs;
+	drm->mode_config.helper_private	= &meson_mode_config_helpers;
 
 	/* Hardware Initialization */
 
-- 
2.20.1