Current implementation of event handling assumes that vblank interrupt is
always called at the right time. It is not true, it can be delayed due to
various reasons. As a result different races can happen. The patch fixes
the issue by using hardware frame counter present in DECON to serialize
vblank and commit completion events.
Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
---
v3:
- handle wrap-around of frame counter
v2:
- added internal decon_get_frame_count function,
- updated frame counter on flush,
- misc style fixes (thank Inki)
---
drivers/gpu/drm/exynos/exynos5433_drm_decon.c | 78 ++++++++++++++++++++++++++-
include/video/exynos5433_decon.h | 8 +++
2 files changed, 85 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
index 2130ccf..cfe6f8a 100644
--- a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
@@ -68,6 +68,8 @@ struct decon_context {
unsigned long flags;
unsigned long out_type;
int first_win;
+ spinlock_t vblank_lock;
+ u32 frame_id;
};
static const uint32_t decon_formats[] = {
@@ -122,6 +124,48 @@ static void decon_disable_vblank(struct exynos_drm_crtc *crtc)
writel(0, ctx->addr + DECON_VIDINTCON0);
}
+/* return number of starts/ends of frame transmissions since reset */
+static u32 decon_get_frame_count(struct decon_context *ctx, bool end)
+{
+ u32 frm, pfrm, status, cnt = 2;
+
+ /* To get consistent result repeat read until frame id is stable.
+ * Usually the loop will be executed once, in rare cases when the loop
+ * is executed at frame change time 2nd pass will be needed.
+ */
+ frm = readl(ctx->addr + DECON_CRFMID);
+ do {
+ status = readl(ctx->addr + DECON_VIDCON1);
+ pfrm = frm;
+ frm = readl(ctx->addr + DECON_CRFMID);
+ } while (frm != pfrm && --cnt);
+
+ /* CRFMID is incremented on BPORCH in case of I80 and on VSYNC in case
+ * of RGB, it should be taken into account.
+ */
+ if (!frm)
+ return 0;
+
+ switch (status & (VIDCON1_VSTATUS_MASK | VIDCON1_I80_ACTIVE)) {
+ case VIDCON1_VSTATUS_VS:
+ if (!(ctx->out_type & IFTYPE_I80))
+ --frm;
+ break;
+ case VIDCON1_VSTATUS_BP:
+ --frm;
+ break;
+ case VIDCON1_I80_ACTIVE:
+ case VIDCON1_VSTATUS_AC:
+ if (end)
+ --frm;
+ break;
+ default:
+ break;
+ }
+
+ return frm;
+}
+
static void decon_setup_trigger(struct decon_context *ctx)
{
if (!(ctx->out_type & (IFTYPE_I80 | I80_HW_TRG)))
@@ -365,11 +409,14 @@ static void decon_disable_plane(struct exynos_drm_crtc *crtc,
static void decon_atomic_flush(struct exynos_drm_crtc *crtc)
{
struct decon_context *ctx = crtc->ctx;
+ unsigned long flags;
int i;
if (test_bit(BIT_SUSPENDED, &ctx->flags))
return;
+ spin_lock_irqsave(&ctx->vblank_lock, flags);
+
for (i = ctx->first_win; i < WINDOWS_NR; i++)
decon_shadow_protect_win(ctx, i, false);
@@ -378,12 +425,18 @@ static void decon_atomic_flush(struct exynos_drm_crtc *crtc)
if (ctx->out_type & IFTYPE_I80)
set_bit(BIT_WIN_UPDATED, &ctx->flags);
+
+ ctx->frame_id = decon_get_frame_count(ctx, true);
+
exynos_crtc_handle_event(crtc);
+
+ spin_unlock_irqrestore(&ctx->vblank_lock, flags);
}
static void decon_swreset(struct decon_context *ctx)
{
unsigned int tries;
+ unsigned long flags;
writel(0, ctx->addr + DECON_VIDCON0);
for (tries = 2000; tries; --tries) {
@@ -401,6 +454,10 @@ static void decon_swreset(struct decon_context *ctx)
WARN(tries == 0, "failed to software reset DECON\n");
+ spin_lock_irqsave(&ctx->vblank_lock, flags);
+ ctx->frame_id = 0;
+ spin_unlock_irqrestore(&ctx->vblank_lock, flags);
+
if (!(ctx->out_type & IFTYPE_HDMI))
return;
@@ -579,6 +636,24 @@ static const struct component_ops decon_component_ops = {
.unbind = decon_unbind,
};
+static void decon_handle_vblank(struct decon_context *ctx)
+{
+ u32 frm;
+
+ spin_lock(&ctx->vblank_lock);
+
+ frm = decon_get_frame_count(ctx, true);
+
+ if (frm != ctx->frame_id) {
+ /* handle only if incremented, take care of wrap-around */
+ if ((s32)(frm - ctx->frame_id) > 0)
+ drm_crtc_handle_vblank(&ctx->crtc->base);
+ ctx->frame_id = frm;
+ }
+
+ spin_unlock(&ctx->vblank_lock);
+}
+
static irqreturn_t decon_irq_handler(int irq, void *dev_id)
{
struct decon_context *ctx = dev_id;
@@ -599,7 +674,7 @@ static irqreturn_t decon_irq_handler(int irq, void *dev_id)
(VIDOUT_INTERLACE_EN_F | VIDOUT_INTERLACE_FIELD_F))
return IRQ_HANDLED;
}
- drm_crtc_handle_vblank(&ctx->crtc->base);
+ decon_handle_vblank(ctx);
}
out:
@@ -672,6 +747,7 @@ static int exynos5433_decon_probe(struct platform_device *pdev)
__set_bit(BIT_SUSPENDED, &ctx->flags);
ctx->dev = dev;
ctx->out_type = (unsigned long)of_device_get_match_data(dev);
+ spin_lock_init(&ctx->vblank_lock);
if (ctx->out_type & IFTYPE_HDMI) {
ctx->first_win = 1;
diff --git a/include/video/exynos5433_decon.h b/include/video/exynos5433_decon.h
index ef8e2a8..352fc0d 100644
--- a/include/video/exynos5433_decon.h
+++ b/include/video/exynos5433_decon.h
@@ -46,6 +46,7 @@
#define DECON_FRAMEFIFO_STATUS 0x0524
#define DECON_CMU 0x1404
#define DECON_UPDATE 0x1410
+#define DECON_CRFMID 0x1414
#define DECON_UPDATE_SCHEME 0x1438
#define DECON_VIDCON1 0x2000
#define DECON_VIDCON2 0x2004
@@ -142,6 +143,13 @@
#define STANDALONE_UPDATE_F (1 << 0)
/* DECON_VIDCON1 */
+#define VIDCON1_LINECNT_MASK (0x0fff << 16)
+#define VIDCON1_I80_ACTIVE (1 << 15)
+#define VIDCON1_VSTATUS_MASK (0x3 << 13)
+#define VIDCON1_VSTATUS_VS (0 << 13)
+#define VIDCON1_VSTATUS_BP (1 << 13)
+#define VIDCON1_VSTATUS_AC (2 << 13)
+#define VIDCON1_VSTATUS_FP (3 << 13)
#define VIDCON1_VCLK_MASK (0x3 << 9)
#define VIDCON1_VCLK_RUN_VDEN_DISABLE (0x3 << 9)
#define VIDCON1_VCLK_HOLD (0x0 << 9)
--
2.7.4
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