[PATCH 02/13] drm/connector: Add helper to check if a mode requires scrambling

[Maxime Ripard <maxime@cerno.tech>]

Most drivers supporting the HDMI scrambling seem to have the HDMI 1.4
maximum frequency open-coded, and a function to test whether a display
mode is above that threshold to control whether or not scrambling should
be enabled.

Let's create a common define and helper for drivers to reuse.

Cc: Emma Anholt <emma@anholt.net>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: linux-tegra@vger.kernel.org
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/tegra/sor.c    |  4 ++--
 drivers/gpu/drm/vc4/vc4_hdmi.c | 21 +++++++++------------
 include/drm/drm_modes.h        | 15 +++++++++++++++
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
index 99a2d627bfeb..390bd04b0d22 100644
--- a/drivers/gpu/drm/tegra/sor.c
+++ b/drivers/gpu/drm/tegra/sor.c
@@ -2192,11 +2192,11 @@ static void tegra_sor_hdmi_scdc_work(struct work_struct *work)
 static void tegra_sor_hdmi_scdc_start(struct tegra_sor *sor)
 {
 	struct drm_scdc *scdc = &sor->output.connector.display_info.hdmi.scdc;
-	struct drm_display_mode *mode;
+	const struct drm_display_mode *mode;
 
 	mode = &sor->output.encoder.crtc->state->adjusted_mode;
 
-	if (mode->clock >= DRM_HDMI_14_MAX_TMDS_CLK_KHZ && scdc->supported) {
+	if (drm_mode_hdmi_requires_scrambling(mode) && scdc->supported) {
 		schedule_delayed_work(&sor->scdc, msecs_to_jiffies(5000));
 		tegra_sor_hdmi_scdc_enable(sor);
 		sor->scdc_enabled = true;
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index fc7247cc1022..fa76ae2c94e4 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -99,11 +99,6 @@
 
 #define HDMI_14_MAX_TMDS_CLK	(DRM_HDMI_14_MAX_TMDS_CLK_KHZ * 1000)
 
-static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode)
-{
-	return mode->clock > DRM_HDMI_14_MAX_TMDS_CLK_KHZ;
-}
-
 static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
 {
 	struct drm_info_node *node = (struct drm_info_node *)m->private;
@@ -260,10 +255,10 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 
 	if (vc4_hdmi->disable_4kp60) {
 		struct drm_device *drm = connector->dev;
-		struct drm_display_mode *mode;
+		const struct drm_display_mode *mode;
 
 		list_for_each_entry(mode, &connector->probed_modes, head) {
-			if (vc4_hdmi_mode_needs_scrambling(mode)) {
+			if (drm_mode_hdmi_requires_scrambling(mode)) {
 				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.");
 			}
@@ -574,7 +569,7 @@ static void vc4_hdmi_set_infoframes(struct drm_encoder *encoder)
 }
 
 static bool vc4_hdmi_supports_scrambling(struct drm_encoder *encoder,
-					 struct drm_display_mode *mode)
+					 const struct drm_display_mode *mode)
 {
 	struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
@@ -597,7 +592,7 @@ static bool vc4_hdmi_supports_scrambling(struct drm_encoder *encoder,
 static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
 {
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
-	struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
+	const struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
 	unsigned long flags;
 
 	lockdep_assert_held(&vc4_hdmi->mutex);
@@ -605,7 +600,7 @@ static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
 	if (!vc4_hdmi_supports_scrambling(encoder, mode))
 		return;
 
-	if (!vc4_hdmi_mode_needs_scrambling(mode))
+	if (!drm_mode_hdmi_requires_scrambling(mode))
 		return;
 
 	drm_scdc_set_high_tmds_clock_ratio(vc4_hdmi->ddc, true);
@@ -1283,7 +1278,8 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder,
 	if (pixel_rate > vc4_hdmi->variant->max_pixel_clock)
 		return -EINVAL;
 
-	if (vc4_hdmi->disable_4kp60 && (pixel_rate > HDMI_14_MAX_TMDS_CLK))
+	if (vc4_hdmi->disable_4kp60 &&
+	    drm_mode_hdmi_requires_scrambling(mode))
 		return -EINVAL;
 
 	vc4_state->pixel_rate = pixel_rate;
@@ -1305,7 +1301,8 @@ vc4_hdmi_encoder_mode_valid(struct drm_encoder *encoder,
 	if ((mode->clock * 1000) > vc4_hdmi->variant->max_pixel_clock)
 		return MODE_CLOCK_HIGH;
 
-	if (vc4_hdmi->disable_4kp60 && vc4_hdmi_mode_needs_scrambling(mode))
+	if (vc4_hdmi->disable_4kp60 &&
+	    drm_mode_hdmi_requires_scrambling(mode))
 		return MODE_CLOCK_HIGH;
 
 	return MODE_OK;
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 29ba4adf0c53..d22816d55836 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -424,6 +424,21 @@ static inline bool drm_mode_is_stereo(const struct drm_display_mode *mode)
 	return mode->flags & DRM_MODE_FLAG_3D_MASK;
 }
 
+/**
+ * drm_mode_hdmi_requires_scrambling - Checks if a mode requires HDMI Scrambling
+ * @mode: DRM display mode
+ *
+ * Checks if a given display mode requires the scrambling to be enabled.
+ *
+ * Returns:
+ * A boolean stating whether it's required or not.
+ */
+static inline bool
+drm_mode_hdmi_requires_scrambling(const struct drm_display_mode *mode)
+{
+	return mode->clock > DRM_HDMI_14_MAX_TMDS_CLK_KHZ;
+}
+
 struct drm_connector;
 struct drm_cmdline_mode;
 
-- 
2.32.0