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Subject[PATCH AUTOSEL 4.19 41/52] drm/exynos/mixer: fix MIXER shadow registry synchronisation code
Date
From: Andrzej Hajda <a.hajda@samsung.com>

[ Upstream commit 6a3b45ada960ac475ec2b4103d43e57943b2b8d3 ]

MIXER on Exynos5 SoCs uses different synchronisation method than Exynos4
to update internal state (shadow registers).
Apparently the driver implements it incorrectly. The rule should be
as follows:
- do not request updating registers until previous request was finished,
ie. MXR_CFG_LAYER_UPDATE_COUNT must be 0.
- before setting registers synchronisation on VSYNC should be turned off,
ie. MXR_STATUS_SYNC_ENABLE should be reset,
- after finishing MXR_STATUS_SYNC_ENABLE should be set again.
The patch hopefully implements it correctly.
Below sample kernel log from page fault caused by the bug:

[ 25.670038] exynos-sysmmu 14650000.sysmmu: 14450000.mixer: PAGE FAULT occurred at 0x2247b800
[ 25.677888] ------------[ cut here ]------------
[ 25.682164] kernel BUG at ../drivers/iommu/exynos-iommu.c:450!
[ 25.687971] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
[ 25.693778] Modules linked in:
[ 25.696816] CPU: 5 PID: 1553 Comm: fb-release_test Not tainted 5.0.0-rc7-01157-g5f86b1566bdd #136
[ 25.705646] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 25.711710] PC is at exynos_sysmmu_irq+0x1c0/0x264
[ 25.716470] LR is at lock_is_held_type+0x44/0x64

v2: added missing MXR_CFG_LAYER_UPDATE bit setting in mixer_enable_sync

Reported-by: Marian Mihailescu <mihailescu2m@gmail.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/exynos/exynos_mixer.c | 110 +++++++++++++++-----------
1 file changed, 66 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
index ffbf4a950f69..522d6c46d7b1 100644
--- a/drivers/gpu/drm/exynos/exynos_mixer.c
+++ b/drivers/gpu/drm/exynos/exynos_mixer.c
@@ -20,6 +20,7 @@
#include "regs-vp.h"

#include <linux/kernel.h>
+#include <linux/ktime.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/i2c.h>
@@ -337,15 +338,62 @@ static void mixer_cfg_vp_blend(struct mixer_context *ctx)
mixer_reg_write(ctx, MXR_VIDEO_CFG, val);
}

-static void mixer_vsync_set_update(struct mixer_context *ctx, bool enable)
+static bool mixer_is_synced(struct mixer_context *ctx)
{
- /* block update on vsync */
- mixer_reg_writemask(ctx, MXR_STATUS, enable ?
- MXR_STATUS_SYNC_ENABLE : 0, MXR_STATUS_SYNC_ENABLE);
+ u32 base, shadow;

+ if (ctx->mxr_ver == MXR_VER_16_0_33_0 ||
+ ctx->mxr_ver == MXR_VER_128_0_0_184)
+ return !(mixer_reg_read(ctx, MXR_CFG) &
+ MXR_CFG_LAYER_UPDATE_COUNT_MASK);
+
+ if (test_bit(MXR_BIT_VP_ENABLED, &ctx->flags) &&
+ vp_reg_read(ctx, VP_SHADOW_UPDATE))
+ return false;
+
+ base = mixer_reg_read(ctx, MXR_CFG);
+ shadow = mixer_reg_read(ctx, MXR_CFG_S);
+ if (base != shadow)
+ return false;
+
+ base = mixer_reg_read(ctx, MXR_GRAPHIC_BASE(0));
+ shadow = mixer_reg_read(ctx, MXR_GRAPHIC_BASE_S(0));
+ if (base != shadow)
+ return false;
+
+ base = mixer_reg_read(ctx, MXR_GRAPHIC_BASE(1));
+ shadow = mixer_reg_read(ctx, MXR_GRAPHIC_BASE_S(1));
+ if (base != shadow)
+ return false;
+
+ return true;
+}
+
+static int mixer_wait_for_sync(struct mixer_context *ctx)
+{
+ ktime_t timeout = ktime_add_us(ktime_get(), 100000);
+
+ while (!mixer_is_synced(ctx)) {
+ usleep_range(1000, 2000);
+ if (ktime_compare(ktime_get(), timeout) > 0)
+ return -ETIMEDOUT;
+ }
+ return 0;
+}
+
+static void mixer_disable_sync(struct mixer_context *ctx)
+{
+ mixer_reg_writemask(ctx, MXR_STATUS, 0, MXR_STATUS_SYNC_ENABLE);
+}
+
+static void mixer_enable_sync(struct mixer_context *ctx)
+{
+ if (ctx->mxr_ver == MXR_VER_16_0_33_0 ||
+ ctx->mxr_ver == MXR_VER_128_0_0_184)
+ mixer_reg_writemask(ctx, MXR_CFG, ~0, MXR_CFG_LAYER_UPDATE);
+ mixer_reg_writemask(ctx, MXR_STATUS, ~0, MXR_STATUS_SYNC_ENABLE);
if (test_bit(MXR_BIT_VP_ENABLED, &ctx->flags))
- vp_reg_write(ctx, VP_SHADOW_UPDATE, enable ?
- VP_SHADOW_UPDATE_ENABLE : 0);
+ vp_reg_write(ctx, VP_SHADOW_UPDATE, VP_SHADOW_UPDATE_ENABLE);
}

static void mixer_cfg_scan(struct mixer_context *ctx, int width, int height)
@@ -482,7 +530,6 @@ static void vp_video_buffer(struct mixer_context *ctx,

spin_lock_irqsave(&ctx->reg_slock, flags);

- vp_reg_write(ctx, VP_SHADOW_UPDATE, 1);
/* interlace or progressive scan mode */
val = (test_bit(MXR_BIT_INTERLACE, &ctx->flags) ? ~0 : 0);
vp_reg_writemask(ctx, VP_MODE, val, VP_MODE_LINE_SKIP);
@@ -537,11 +584,6 @@ static void vp_video_buffer(struct mixer_context *ctx,
vp_regs_dump(ctx);
}

-static void mixer_layer_update(struct mixer_context *ctx)
-{
- mixer_reg_writemask(ctx, MXR_CFG, ~0, MXR_CFG_LAYER_UPDATE);
-}
-
static void mixer_graph_buffer(struct mixer_context *ctx,
struct exynos_drm_plane *plane)
{
@@ -618,11 +660,6 @@ static void mixer_graph_buffer(struct mixer_context *ctx,
mixer_cfg_layer(ctx, win, priority, true);
mixer_cfg_gfx_blend(ctx, win, fb->format->has_alpha);

- /* layer update mandatory for mixer 16.0.33.0 */
- if (ctx->mxr_ver == MXR_VER_16_0_33_0 ||
- ctx->mxr_ver == MXR_VER_128_0_0_184)
- mixer_layer_update(ctx);
-
spin_unlock_irqrestore(&ctx->reg_slock, flags);

mixer_regs_dump(ctx);
@@ -687,7 +724,7 @@ static void mixer_win_reset(struct mixer_context *ctx)
static irqreturn_t mixer_irq_handler(int irq, void *arg)
{
struct mixer_context *ctx = arg;
- u32 val, base, shadow;
+ u32 val;

spin_lock(&ctx->reg_slock);

@@ -701,26 +738,9 @@ static irqreturn_t mixer_irq_handler(int irq, void *arg)
val &= ~MXR_INT_STATUS_VSYNC;

/* interlace scan need to check shadow register */
- if (test_bit(MXR_BIT_INTERLACE, &ctx->flags)) {
- if (test_bit(MXR_BIT_VP_ENABLED, &ctx->flags) &&
- vp_reg_read(ctx, VP_SHADOW_UPDATE))
- goto out;
-
- base = mixer_reg_read(ctx, MXR_CFG);
- shadow = mixer_reg_read(ctx, MXR_CFG_S);
- if (base != shadow)
- goto out;
-
- base = mixer_reg_read(ctx, MXR_GRAPHIC_BASE(0));
- shadow = mixer_reg_read(ctx, MXR_GRAPHIC_BASE_S(0));
- if (base != shadow)
- goto out;
-
- base = mixer_reg_read(ctx, MXR_GRAPHIC_BASE(1));
- shadow = mixer_reg_read(ctx, MXR_GRAPHIC_BASE_S(1));
- if (base != shadow)
- goto out;
- }
+ if (test_bit(MXR_BIT_INTERLACE, &ctx->flags)
+ && !mixer_is_synced(ctx))
+ goto out;

drm_crtc_handle_vblank(&ctx->crtc->base);
}
@@ -895,12 +915,14 @@ static void mixer_disable_vblank(struct exynos_drm_crtc *crtc)

static void mixer_atomic_begin(struct exynos_drm_crtc *crtc)
{
- struct mixer_context *mixer_ctx = crtc->ctx;
+ struct mixer_context *ctx = crtc->ctx;

- if (!test_bit(MXR_BIT_POWERED, &mixer_ctx->flags))
+ if (!test_bit(MXR_BIT_POWERED, &ctx->flags))
return;

- mixer_vsync_set_update(mixer_ctx, false);
+ if (mixer_wait_for_sync(ctx))
+ dev_err(ctx->dev, "timeout waiting for VSYNC\n");
+ mixer_disable_sync(ctx);
}

static void mixer_update_plane(struct exynos_drm_crtc *crtc,
@@ -942,7 +964,7 @@ static void mixer_atomic_flush(struct exynos_drm_crtc *crtc)
if (!test_bit(MXR_BIT_POWERED, &mixer_ctx->flags))
return;

- mixer_vsync_set_update(mixer_ctx, true);
+ mixer_enable_sync(mixer_ctx);
exynos_crtc_handle_event(crtc);
}

@@ -957,7 +979,7 @@ static void mixer_enable(struct exynos_drm_crtc *crtc)

exynos_drm_pipe_clk_enable(crtc, true);

- mixer_vsync_set_update(ctx, false);
+ mixer_disable_sync(ctx);

mixer_reg_writemask(ctx, MXR_STATUS, ~0, MXR_STATUS_SOFT_RESET);

@@ -970,7 +992,7 @@ static void mixer_enable(struct exynos_drm_crtc *crtc)

mixer_commit(ctx);

- mixer_vsync_set_update(ctx, true);
+ mixer_enable_sync(ctx);

set_bit(MXR_BIT_POWERED, &ctx->flags);
}
--
2.19.1
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