[PATCH v7 25/30] drm/vc4: hdmi: Convert to common HDMI 2.0 SCDC scrambling helpers
Cristian Ciocaltea
cristian.ciocaltea at collabora.com
Mon Jun 1 15:44:25 PDT 2026
Replace the vc4-local scrambling implementation with the newly
introduced DRM common SCDC scrambling infrastructure:
- Advertise source-side scrambling support by setting
connector->hdmi.scrambling_supported based on the variant's
max_pixel_clock before drmm_connector_hdmi_init().
- Provide minimal .scrambler_{enable|disable} connector callbacks that
only toggle the VC5 HDMI_SCRAMBLER_CTL register. Sink-side SCDC
programming and periodic status monitoring are now delegated to
drm_scdc_{start|stop}_scrambling().
- Replace vc4_hdmi_enable_scrambling() with a conditional call to
drm_scdc_start_scrambling() in post_crtc_enable, gated on
conn_state->hdmi.scrambler_needed (computed by the HDMI state helper).
- Replace vc4_hdmi_disable_scrambling() with drm_scdc_stop_scrambling()
in post_crtc_disable.
- Drop vc4_hdmi_reset_link() and vc4_hdmi_handle_hotplug(), switching
the .detect_ctx() path to
drm_atomic_helper_connector_hdmi_hotplug_ctx() which internally calls
drm_scdc_sync_status() to trigger a CRTC reset on reconnection.
- Drop the local scrambling_work delayed workqueue and scdc_enabled
flag, now tracked by the common drm_connector_hdmi layer.
- Drop vc4_hdmi_supports_scrambling() and
vc4_hdmi_mode_needs_scrambling() helpers, inlining the remaining 4KP60
warning with an explicit drm_hdmi_compute_mode_clock() check.
- Seed connector->hdmi.scrambler_enabled = true in connector_init() to
ensure drm_scdc_stop_scrambling() runs at boot and disables any stale
scrambling state left by the bootloader.
No functional change is expected for the supported modes.
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at collabora.com>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 265 ++++++-----------------------------------
drivers/gpu/drm/vc4/vc4_hdmi.h | 8 --
2 files changed, 35 insertions(+), 238 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 046ac4f43ba8..02f6ca6ab52b 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -114,31 +114,6 @@
#define HSM_MIN_CLOCK_FREQ 120000000
#define CEC_CLOCK_FREQ 40000
-static bool vc4_hdmi_supports_scrambling(struct vc4_hdmi *vc4_hdmi)
-{
- struct drm_display_info *display = &vc4_hdmi->connector.display_info;
-
- lockdep_assert_held(&vc4_hdmi->mutex);
-
- if (!display->is_hdmi)
- return false;
-
- if (!display->hdmi.scdc.supported ||
- !display->hdmi.scdc.scrambling.supported)
- return false;
-
- return true;
-}
-
-static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode,
- unsigned int bpc,
- enum drm_output_color_format fmt)
-{
- unsigned long long clock = drm_hdmi_compute_mode_clock(mode, bpc, fmt);
-
- return clock > HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ;
-}
-
static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
{
struct drm_debugfs_entry *entry = m->private;
@@ -272,124 +247,6 @@ static void vc4_hdmi_cec_update_clk_div(struct vc4_hdmi *vc4_hdmi)
static void vc4_hdmi_cec_update_clk_div(struct vc4_hdmi *vc4_hdmi) {}
#endif
-static int vc4_hdmi_reset_link(struct drm_connector *connector,
- struct drm_modeset_acquire_ctx *ctx)
-{
- struct drm_device *drm;
- struct vc4_hdmi *vc4_hdmi;
- struct drm_connector_state *conn_state;
- struct drm_crtc_state *crtc_state;
- struct drm_crtc *crtc;
- bool scrambling_needed;
- u8 config;
- int ret;
-
- if (!connector)
- return 0;
-
- drm = connector->dev;
- ret = drm_modeset_lock(&drm->mode_config.connection_mutex, ctx);
- if (ret)
- return ret;
-
- conn_state = connector->state;
- crtc = conn_state->crtc;
- if (!crtc)
- return 0;
-
- ret = drm_modeset_lock(&crtc->mutex, ctx);
- if (ret)
- return ret;
-
- crtc_state = crtc->state;
- if (!crtc_state->active)
- return 0;
-
- vc4_hdmi = connector_to_vc4_hdmi(connector);
- mutex_lock(&vc4_hdmi->mutex);
-
- if (!vc4_hdmi_supports_scrambling(vc4_hdmi)) {
- mutex_unlock(&vc4_hdmi->mutex);
- return 0;
- }
-
- scrambling_needed = vc4_hdmi_mode_needs_scrambling(&vc4_hdmi->saved_adjusted_mode,
- vc4_hdmi->output_bpc,
- vc4_hdmi->output_format);
- if (!scrambling_needed) {
- mutex_unlock(&vc4_hdmi->mutex);
- return 0;
- }
-
- if (conn_state->commit &&
- !try_wait_for_completion(&conn_state->commit->hw_done)) {
- mutex_unlock(&vc4_hdmi->mutex);
- return 0;
- }
-
- ret = drm_scdc_readb(connector->ddc, SCDC_TMDS_CONFIG, &config);
- if (ret < 0) {
- drm_err(drm, "Failed to read TMDS config: %d\n", ret);
- mutex_unlock(&vc4_hdmi->mutex);
- return 0;
- }
-
- if (!!(config & SCDC_SCRAMBLING_ENABLE) == scrambling_needed) {
- mutex_unlock(&vc4_hdmi->mutex);
- return 0;
- }
-
- mutex_unlock(&vc4_hdmi->mutex);
-
- /*
- * HDMI 2.0 says that one should not send scrambled data
- * prior to configuring the sink scrambling, and that
- * TMDS clock/data transmission should be suspended when
- * changing the TMDS clock rate in the sink. So let's
- * just do a full modeset here, even though some sinks
- * would be perfectly happy if were to just reconfigure
- * the SCDC settings on the fly.
- */
- return drm_atomic_helper_reset_crtc(crtc, ctx);
-}
-
-static void vc4_hdmi_handle_hotplug(struct vc4_hdmi *vc4_hdmi,
- struct drm_modeset_acquire_ctx *ctx,
- enum drm_connector_status status)
-{
- struct drm_connector *connector = &vc4_hdmi->connector;
- int ret;
-
- /*
- * NOTE: This function should really be called with vc4_hdmi->mutex
- * held, but doing so results in reentrancy issues since
- * cec_s_phys_addr() might call .adap_enable, which leads to that
- * funtion being called with our mutex held.
- *
- * A similar situation occurs with vc4_hdmi_reset_link() that
- * will call into our KMS hooks if the scrambling was enabled.
- *
- * Concurrency isn't an issue at the moment since we don't share
- * any state with any of the other frameworks so we can ignore
- * the lock for now.
- */
-
- drm_atomic_helper_connector_hdmi_hotplug(connector, status);
-
- if (status != connector_status_connected)
- return;
-
- for (;;) {
- ret = vc4_hdmi_reset_link(connector, ctx);
- if (ret == -EDEADLK) {
- drm_modeset_backoff(ctx);
- continue;
- }
-
- break;
- }
-}
-
static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
struct drm_modeset_acquire_ctx *ctx,
bool force)
@@ -401,8 +258,8 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
/*
* NOTE: This function should really take vc4_hdmi->mutex, but
* doing so results in reentrancy issues since
- * vc4_hdmi_handle_hotplug() can call into other functions that
- * would take the mutex while it's held here.
+ * drm_atomic_helper_connector_hdmi_hotplug_ctx() can call into other
+ * functions that would take the mutex while it's held here.
*
* Concurrency isn't an issue at the moment since we don't share
* any state with any of the other frameworks so we can ignore
@@ -425,10 +282,11 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
status = connector_status_connected;
}
- vc4_hdmi_handle_hotplug(vc4_hdmi, ctx, status);
+ ret = drm_atomic_helper_connector_hdmi_hotplug_ctx(connector, status, ctx);
+
pm_runtime_put(&vc4_hdmi->pdev->dev);
- return status;
+ return ret == -EDEADLK ? ret : status;
}
static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
@@ -441,9 +299,12 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
if (!vc4->hvs->vc5_hdmi_enable_hdmi_20) {
struct drm_device *drm = connector->dev;
const struct drm_display_mode *mode;
+ unsigned long long clock;
list_for_each_entry(mode, &connector->probed_modes, head) {
- if (vc4_hdmi_mode_needs_scrambling(mode, 8, DRM_OUTPUT_COLOR_FORMAT_RGB444)) {
+ clock = drm_hdmi_compute_mode_clock(mode, 8,
+ DRM_OUTPUT_COLOR_FORMAT_RGB444);
+ if (clock > HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ) {
drm_warn_once(drm, "The core clock cannot reach frequencies high enough to support 4k @ 60Hz.");
drm_warn_once(drm, "Please change your config.txt file to add hdmi_enable_4kp60.");
}
@@ -540,6 +401,9 @@ static int vc4_hdmi_connector_init(struct drm_device *dev,
if (vc4_hdmi->variant->supports_hdr)
max_bpc = 12;
+ connector->hdmi.scrambler_supported =
+ vc4_hdmi->variant->max_pixel_clock > HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ;
+
ret = drmm_connector_hdmi_init(dev, connector,
"Broadcom", "Videocore",
&vc4_hdmi_connector_funcs,
@@ -561,6 +425,14 @@ static int vc4_hdmi_connector_init(struct drm_device *dev,
drm_connector_helper_add(connector, &vc4_hdmi_connector_helper_funcs);
+ /*
+ * Since we don't know the state of the controller and its
+ * display (if any), let's assume it's always enabled.
+ * drm_scdc_stop_scrambling() will thus run at boot, make
+ * sure it's disabled, and avoid any inconsistency.
+ */
+ connector->hdmi.scrambler_enabled = connector->hdmi.scrambler_supported;
+
/*
* Some of the properties below require access to state, like bpc.
* Allocate some default initial connector state with our reset helper.
@@ -786,93 +658,30 @@ static int vc4_hdmi_write_spd_infoframe(struct drm_connector *connector,
buffer, len);
}
-#define SCRAMBLING_POLLING_DELAY_MS 1000
-
-static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
+static int vc4_hdmi_scrambler_enable(struct drm_connector *connector)
{
- struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
- struct drm_connector *connector = &vc4_hdmi->connector;
- struct drm_device *drm = connector->dev;
- const struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
+ struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
unsigned long flags;
- int idx;
-
- lockdep_assert_held(&vc4_hdmi->mutex);
-
- if (!vc4_hdmi_supports_scrambling(vc4_hdmi))
- return;
-
- if (!vc4_hdmi_mode_needs_scrambling(mode,
- vc4_hdmi->output_bpc,
- vc4_hdmi->output_format))
- return;
-
- if (!drm_dev_enter(drm, &idx))
- return;
-
- drm_scdc_set_high_tmds_clock_ratio(connector, true);
- drm_scdc_set_scrambling(connector, true);
spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
HDMI_WRITE(HDMI_SCRAMBLER_CTL, HDMI_READ(HDMI_SCRAMBLER_CTL) |
VC5_HDMI_SCRAMBLER_CTL_ENABLE);
spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);
- drm_dev_exit(idx);
-
- vc4_hdmi->scdc_enabled = true;
-
- queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
- msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
+ return 0;
}
-static void vc4_hdmi_disable_scrambling(struct drm_encoder *encoder)
+static int vc4_hdmi_scrambler_disable(struct drm_connector *connector)
{
- struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
- struct drm_connector *connector = &vc4_hdmi->connector;
- struct drm_device *drm = connector->dev;
+ struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
unsigned long flags;
- int idx;
-
- lockdep_assert_held(&vc4_hdmi->mutex);
-
- if (!vc4_hdmi->scdc_enabled)
- return;
-
- vc4_hdmi->scdc_enabled = false;
-
- if (delayed_work_pending(&vc4_hdmi->scrambling_work))
- cancel_delayed_work_sync(&vc4_hdmi->scrambling_work);
-
- if (!drm_dev_enter(drm, &idx))
- return;
spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
HDMI_WRITE(HDMI_SCRAMBLER_CTL, HDMI_READ(HDMI_SCRAMBLER_CTL) &
~VC5_HDMI_SCRAMBLER_CTL_ENABLE);
spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);
- drm_scdc_set_scrambling(connector, false);
- drm_scdc_set_high_tmds_clock_ratio(connector, false);
-
- drm_dev_exit(idx);
-}
-
-static void vc4_hdmi_scrambling_wq(struct work_struct *work)
-{
- struct vc4_hdmi *vc4_hdmi = container_of(to_delayed_work(work),
- struct vc4_hdmi,
- scrambling_work);
- struct drm_connector *connector = &vc4_hdmi->connector;
-
- if (drm_scdc_get_scrambling_status(connector))
- return;
-
- drm_scdc_set_high_tmds_clock_ratio(connector, true);
- drm_scdc_set_scrambling(connector, true);
-
- queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
- msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
+ return 0;
}
static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
@@ -917,7 +726,7 @@ static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);
}
- vc4_hdmi_disable_scrambling(encoder);
+ drm_scdc_stop_scrambling(&vc4_hdmi->connector);
drm_dev_exit(idx);
@@ -1625,6 +1434,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
struct drm_display_info *display = &vc4_hdmi->connector.display_info;
bool hsync_pos = mode->flags & DRM_MODE_FLAG_PHSYNC;
bool vsync_pos = mode->flags & DRM_MODE_FLAG_PVSYNC;
+ struct drm_connector_state *conn_state;
unsigned long flags;
int ret;
int idx;
@@ -1693,7 +1503,10 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
}
vc4_hdmi_recenter_fifo(vc4_hdmi);
- vc4_hdmi_enable_scrambling(encoder);
+
+ conn_state = drm_atomic_get_new_connector_state(state, connector);
+ if (conn_state && conn_state->hdmi.scrambler_needed)
+ drm_scdc_start_scrambling(connector);
drm_dev_exit(idx);
@@ -1739,7 +1552,9 @@ vc4_hdmi_connector_clock_valid(const struct drm_connector *connector,
}
static const struct drm_connector_hdmi_funcs vc4_hdmi_hdmi_connector_funcs = {
- .tmds_char_rate_valid = vc4_hdmi_connector_clock_valid,
+ .tmds_char_rate_valid = vc4_hdmi_connector_clock_valid,
+ .scrambler_enable = vc4_hdmi_scrambler_enable,
+ .scrambler_disable = vc4_hdmi_scrambler_disable,
.avi = {
.clear_infoframe = vc4_hdmi_clear_avi_infoframe,
.write_infoframe = vc4_hdmi_write_avi_infoframe,
@@ -3233,7 +3048,6 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
return ret;
spin_lock_init(&vc4_hdmi->hw_lock);
- INIT_DELAYED_WORK(&vc4_hdmi->scrambling_work, vc4_hdmi_scrambling_wq);
dev_set_drvdata(dev, vc4_hdmi);
encoder = &vc4_hdmi->encoder.base;
@@ -3246,15 +3060,6 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
vc4_hdmi->pdev = pdev;
vc4_hdmi->variant = variant;
- /*
- * Since we don't know the state of the controller and its
- * display (if any), let's assume it's always enabled.
- * vc4_hdmi_disable_scrambling() will thus run at boot, make
- * sure it's disabled, and avoid any inconsistency.
- */
- if (variant->max_pixel_clock > HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ)
- vc4_hdmi->scdc_enabled = true;
-
ret = variant->init_resources(drm, vc4_hdmi);
if (ret)
return ret;
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
index 29d461d4ee49..58c92ebc2677 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
@@ -118,8 +118,6 @@ struct vc4_hdmi {
struct vc4_encoder encoder;
struct drm_connector connector;
- struct delayed_work scrambling_work;
-
struct i2c_adapter *ddc;
void __iomem *hdmicore_regs;
void __iomem *hd_regs;
@@ -193,12 +191,6 @@ struct vc4_hdmi {
*/
bool packet_ram_enabled;
- /**
- * @scdc_enabled: Is the HDMI controller currently running with
- * the scrambler on? Protected by @mutex.
- */
- bool scdc_enabled;
-
/**
* @output_bpc: Copy of @drm_connector_state.hdmi.output_bpc for
* use outside of KMS hooks. Protected by @mutex.
--
2.54.0
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