linux-kernel - [PATCH v2 2/4] drm/vc4: hdmi: Add pixel bvb clock control

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Date:   Tue,  1 Sep 2020 13:07:57 +0900
From:   Hoegeun Kwon <hoegeun.kwon@...sung.com>
To:     nsaenzjulienne@...e.de, eric@...olt.net, maxime@...no.tech,
        stefan.wahren@...e.com, dave.stevenson@...pberrypi.com
Cc:     devicetree@...r.kernel.org, tim.gover@...pberrypi.com,
        sboyd@...nel.org, mturquette@...libre.com, kdasu.kdev@...il.com,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-clk@...r.kernel.org, robh+dt@...nel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org, phil@...pberrypi.com,
        linux-arm-kernel@...ts.infradead.org, hoegeun.kwon@...sung.com
Subject: [PATCH v2 2/4] drm/vc4: hdmi: Add pixel bvb clock control

There is a problem that the output does not work at a resolution
exceeding FHD. To solve this, we need to adjust the bvb clock at a
resolution exceeding FHD.

Signed-off-by: Hoegeun Kwon <hoegeun.kwon@...sung.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 25 +++++++++++++++++++++++++
 drivers/gpu/drm/vc4/vc4_hdmi.h |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 95ec5eedea39..eb3192d1fd86 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -80,6 +80,7 @@
 # define VC4_HD_M_ENABLE			BIT(0)
 
 #define CEC_CLOCK_FREQ 40000
+#define VC4_HSM_MID_CLOCK 149985000
 
 static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
 {
@@ -380,6 +381,7 @@ static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder)
 	HDMI_WRITE(HDMI_VID_CTL,
 		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_ENABLE);
 
+	clk_disable_unprepare(vc4_hdmi->pixel_bvb_clock);
 	clk_disable_unprepare(vc4_hdmi->hsm_clock);
 	clk_disable_unprepare(vc4_hdmi->pixel_clock);
 
@@ -638,6 +640,23 @@ static void vc4_hdmi_encoder_pre_crtc_configure(struct drm_encoder *encoder)
 		return;
 	}
 
+	ret = clk_set_rate(vc4_hdmi->pixel_bvb_clock,
+			(hsm_rate > VC4_HSM_MID_CLOCK ? 150000000 : 75000000));
+	if (ret) {
+		DRM_ERROR("Failed to set pixel bvb clock rate: %d\n", ret);
+		clk_disable_unprepare(vc4_hdmi->hsm_clock);
+		clk_disable_unprepare(vc4_hdmi->pixel_clock);
+		return;
+	}
+
+	ret = clk_prepare_enable(vc4_hdmi->pixel_bvb_clock);
+	if (ret) {
+		DRM_ERROR("Failed to turn on pixel bvb clock: %d\n", ret);
+		clk_disable_unprepare(vc4_hdmi->hsm_clock);
+		clk_disable_unprepare(vc4_hdmi->pixel_clock);
+		return;
+	}
+
 	if (vc4_hdmi->variant->reset)
 		vc4_hdmi->variant->reset(vc4_hdmi);
 
@@ -1593,6 +1612,12 @@ static int vc5_hdmi_init_resources(struct vc4_hdmi *vc4_hdmi)
 		return PTR_ERR(vc4_hdmi->audio_clock);
 	}
 
+	vc4_hdmi->pixel_bvb_clock = devm_clk_get(dev, "bvb");
+	if (IS_ERR(vc4_hdmi->pixel_bvb_clock)) {
+		DRM_ERROR("Failed to get pixel bvb clock\n");
+		return PTR_ERR(vc4_hdmi->pixel_bvb_clock);
+	}
+
 	vc4_hdmi->reset = devm_reset_control_get(dev, NULL);
 	if (IS_ERR(vc4_hdmi->reset)) {
 		DRM_ERROR("Failed to get HDMI reset line\n");
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
index 0806c6d9f24e..63c6f8bddf1d 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
@@ -147,6 +147,7 @@ struct vc4_hdmi {
 	struct clk *pixel_clock;
 	struct clk *hsm_clock;
 	struct clk *audio_clock;
+	struct clk *pixel_bvb_clock;
 
 	struct reset_control *reset;
 
-- 
2.17.1