drm/exynos/vidi: use timer for vblanks instead of sleeping worker

VIDI driver uses fake vblank handler to generate vblank events.
It was implemented using worker which slept for vblank time, additionally
it did not work if there were no page flips. The patch replaces it with
timer, uses drm_crtc_vblank_(on|off) helpers to manage it and fixes
behavior for non-page-flip cases.
This change allows further improvements of vblank in exynos-drm framework.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_vidi.c

@@ -15,6 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/component.h>
+#include <linux/timer.h>
 
 #include <drm/exynos_drm.h>
 
@@ -28,6 +29,9 @@
 #include "exynos_drm_plane.h"
 #include "exynos_drm_vidi.h"
 
+/* VIDI uses fixed refresh rate of 50Hz */
+#define VIDI_REFRESH_TIME (1000 / 50)
+
 /* vidi has totally three virtual windows. */
 #define WINDOWS_NR		3
 
@@ -43,12 +47,9 @@ struct vidi_context {
 	struct exynos_drm_plane		planes[WINDOWS_NR];
 	struct edid			*raw_edid;
 	unsigned int			clkdiv;
-	unsigned long			irq_flags;
 	unsigned int			connected;
-	bool				vblank_on;
 	bool				suspended;
-	bool				direct_vblank;
-	struct work_struct		work;
+	struct timer_list		timer;
 	struct mutex			lock;
 	int				pipe;
 };
@@ -102,30 +103,14 @@ static int vidi_enable_vblank(struct exynos_drm_crtc *crtc)
 	if (ctx->suspended)
 		return -EPERM;
 
-	if (!test_and_set_bit(0, &ctx->irq_flags))
-		ctx->vblank_on = true;
-
-	ctx->direct_vblank = true;
-
-	/*
-	 * in case of page flip request, vidi_finish_pageflip function
-	 * will not be called because direct_vblank is true and then
-	 * that function will be called by crtc_ops->update_plane callback
-	 */
-	schedule_work(&ctx->work);
+	mod_timer(&ctx->timer,
+		jiffies + msecs_to_jiffies(VIDI_REFRESH_TIME) - 1);
 
 	return 0;
 }
 
 static void vidi_disable_vblank(struct exynos_drm_crtc *crtc)
 {
-	struct vidi_context *ctx = crtc->ctx;
-
-	if (ctx->suspended)
-		return;
-
-	if (test_and_clear_bit(0, &ctx->irq_flags))
-		ctx->vblank_on = false;
 }
 
 static void vidi_update_plane(struct exynos_drm_crtc *crtc,
@@ -140,9 +125,6 @@ static void vidi_update_plane(struct exynos_drm_crtc *crtc,
 
 	addr = exynos_drm_fb_dma_addr(state->fb, 0);
 	DRM_DEBUG_KMS("dma_addr = %pad\n", &addr);
-
-	if (ctx->vblank_on)
-		schedule_work(&ctx->work);
 }
 
 static void vidi_enable(struct exynos_drm_crtc *crtc)
@@ -153,17 +135,17 @@ static void vidi_enable(struct exynos_drm_crtc *crtc)
 
 	ctx->suspended = false;
 
-	/* if vblank was enabled status, enable it again. */
-	if (test_and_clear_bit(0, &ctx->irq_flags))
-		vidi_enable_vblank(ctx->crtc);
-
 	mutex_unlock(&ctx->lock);
+
+	drm_crtc_vblank_on(&crtc->base);
 }
 
 static void vidi_disable(struct exynos_drm_crtc *crtc)
 {
 	struct vidi_context *ctx = crtc->ctx;
 
+	drm_crtc_vblank_off(&crtc->base);
+
 	mutex_lock(&ctx->lock);
 
 	ctx->suspended = true;
@@ -190,28 +172,17 @@ static const struct exynos_drm_crtc_ops vidi_crtc_ops = {
 	.update_plane = vidi_update_plane,
 };
 
-static void vidi_fake_vblank_handler(struct work_struct *work)
+static void vidi_fake_vblank_timer(unsigned long arg)
 {
-	struct vidi_context *ctx = container_of(work, struct vidi_context,
-					work);
+	struct vidi_context *ctx = (void *)arg;
 	int win;
 
 	if (ctx->pipe < 0)
 		return;
 
-	/* refresh rate is about 50Hz. */
-	usleep_range(16000, 20000);
-
-	mutex_lock(&ctx->lock);
-
-	if (ctx->direct_vblank) {
-		drm_crtc_handle_vblank(&ctx->crtc->base);
-		ctx->direct_vblank = false;
-		mutex_unlock(&ctx->lock);
-		return;
-	}
-
-	mutex_unlock(&ctx->lock);
+	if (drm_crtc_handle_vblank(&ctx->crtc->base))
+		mod_timer(&ctx->timer,
+			jiffies + msecs_to_jiffies(VIDI_REFRESH_TIME) - 1);
 
 	for (win = 0 ; win < WINDOWS_NR ; win++) {
 		struct exynos_drm_plane *plane = &ctx->planes[win];
@@ -489,6 +460,9 @@ static int vidi_bind(struct device *dev, struct device *master, void *data)
 
 static void vidi_unbind(struct device *dev, struct device *master, void *data)
 {
+	struct vidi_context *ctx = dev_get_drvdata(dev);
+
+	del_timer_sync(&ctx->timer);
 }
 
 static const struct component_ops vidi_component_ops = {
@@ -507,7 +481,7 @@ static int vidi_probe(struct platform_device *pdev)
 
 	ctx->pdev = pdev;
 
-	INIT_WORK(&ctx->work, vidi_fake_vblank_handler);
+	setup_timer(&ctx->timer, vidi_fake_vblank_timer, (unsigned long)ctx);
 
 	mutex_init(&ctx->lock);