openwrt/target/linux/bcm27xx/patches-5.15/950-0633-drm-vc4-hdmi-Take-bpp-into-account-for-the-scrambler.patch

From 8b7091e1795e50b559b7896b71c45df4fc83353b Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Fri, 10 Dec 2021 15:00:04 +0100
Subject: [PATCH] drm/vc4: hdmi: Take bpp into account for the
 scrambler

The current code only base its decision for whether the scrambler must be
enabled or not on the pixel clock of the mode, but doesn't take the bits
per color into account.

Let's leverage the new function to compute the clock rate in the
scrambler setup code.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 17 +++++++++++++----
 drivers/gpu/drm/vc4/vc4_hdmi.h |  5 +++++
 2 files changed, 18 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -103,9 +103,17 @@
 
 #define HDMI_14_MAX_TMDS_CLK   (340 * 1000 * 1000)
 
-static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode)
+
+static unsigned long long
+vc4_hdmi_encoder_compute_mode_clock(const struct drm_display_mode *mode,
+				    unsigned int bpc);
+
+static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode,
+					   unsigned int bpc)
 {
-	return (mode->clock * 1000) > HDMI_14_MAX_TMDS_CLK;
+	unsigned long long clock = vc4_hdmi_encoder_compute_mode_clock(mode, bpc);
+
+	return clock > HDMI_14_MAX_TMDS_CLK;
 }
 
 static bool vc4_hdmi_is_full_range_rgb(struct vc4_hdmi *vc4_hdmi,
@@ -277,7 +285,7 @@ static int vc4_hdmi_connector_get_modes(
 		struct drm_display_mode *mode;
 
 		list_for_each_entry(mode, &connector->probed_modes, head) {
-			if (vc4_hdmi_mode_needs_scrambling(mode)) {
+			if (vc4_hdmi_mode_needs_scrambling(mode, 8)) {
 				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.");
 			}
@@ -628,7 +636,7 @@ static void vc4_hdmi_enable_scrambling(s
 	if (!vc4_hdmi_supports_scrambling(encoder, mode))
 		return;
 
-	if (!vc4_hdmi_mode_needs_scrambling(mode))
+	if (!vc4_hdmi_mode_needs_scrambling(mode, vc4_hdmi->output_bpc))
 		return;
 
 	drm_scdc_set_high_tmds_clock_ratio(vc4_hdmi->ddc, true);
@@ -1245,6 +1253,7 @@ static void vc4_hdmi_encoder_atomic_mode
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
 
 	mutex_lock(&vc4_hdmi->mutex);
+	vc4_hdmi->output_bpc = conn_state->max_bpc;
 	memcpy(&vc4_hdmi->saved_adjusted_mode,
 	       &crtc_state->adjusted_mode,
 	       sizeof(vc4_hdmi->saved_adjusted_mode));
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
@@ -221,6 +221,11 @@ struct vc4_hdmi {
 	 */
 	bool scdc_enabled;
 
+	/**
+	 * @output_bpc: BPC currently being used. Protected by @mutex.
+	 */
+	unsigned int output_bpc;
+
 	/* VC5 debugfs regset */
 	struct debugfs_regset32 cec_regset;
 	struct debugfs_regset32 csc_regset;