linux-kernel - [PATCH v4 3/7] drm/msm/mdp4: register the LVDS PLL as a clock provider

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Message-Id: <20250425-fd-mdp4-lvds-v4-3-6b212160b44c@oss.qualcomm.com>
Date: Fri, 25 Apr 2025 12:51:53 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: [PATCH v4 3/7] drm/msm/mdp4: register the LVDS PLL as a clock
 provider

From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

The LVDS/LCDC controller uses pixel clock coming from the multimedia
controller (mmcc) rather than using the PLL directly. Stop using LVDS
PLL directly and register it as a clock provider. Use lcdc_clk as a
pixel clock for the LCDC.

Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h          |  2 +-
 drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c |  3 +-
 drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_pll.c     | 45 ++++++++++++++++-------
 3 files changed, 34 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h
index 142ccb68b435263f91ba1ab27676e426d43e5d84..3d7ffd874e0d234f450f6170e623f87572456757 100644
--- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h
+++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h
@@ -207,6 +207,6 @@ static inline struct drm_encoder *mdp4_dsi_encoder_init(struct drm_device *dev)
 }
 #endif
 
-struct clk *mpd4_lvds_pll_init(struct drm_device *dev);
+struct clk *mpd4_get_lcdc_clock(struct drm_device *dev);
 
 #endif /* __MDP4_KMS_H__ */
diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c
index 8bbc7fb881d599e7d309cc61bda83697fecd253a..8694e5d7d3f012070c72214df063a6488b2ef707 100644
--- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c
+++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c
@@ -380,8 +380,7 @@ struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev,
 
 	drm_encoder_helper_add(encoder, &mdp4_lcdc_encoder_helper_funcs);
 
-	/* TODO: do we need different pll in other cases? */
-	mdp4_lcdc_encoder->lcdc_clk = mpd4_lvds_pll_init(dev);
+	mdp4_lcdc_encoder->lcdc_clk = mpd4_get_lcdc_clock(dev);
 	if (IS_ERR(mdp4_lcdc_encoder->lcdc_clk)) {
 		DRM_DEV_ERROR(dev->dev, "failed to get lvds_clk\n");
 		return ERR_CAST(mdp4_lcdc_encoder->lcdc_clk);
diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_pll.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_pll.c
index ab8c0c187fb2cd05e26f5019244af15f1b2470c8..df2bbd475cc2a11da20ac07be8e757527ef41ae8 100644
--- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_pll.c
+++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_pll.c
@@ -133,29 +133,48 @@ static struct clk_init_data pll_init = {
 	.num_parents = ARRAY_SIZE(mpd4_lvds_pll_parents),
 };
 
-struct clk *mpd4_lvds_pll_init(struct drm_device *dev)
+static struct clk_hw *mpd4_lvds_pll_init(struct drm_device *dev)
 {
 	struct mdp4_lvds_pll *lvds_pll;
-	struct clk *clk;
 	int ret;
 
 	lvds_pll = devm_kzalloc(dev->dev, sizeof(*lvds_pll), GFP_KERNEL);
-	if (!lvds_pll) {
-		ret = -ENOMEM;
-		goto fail;
-	}
+	if (!lvds_pll)
+		return ERR_PTR(-ENOMEM);
 
 	lvds_pll->dev = dev;
 
 	lvds_pll->pll_hw.init = &pll_init;
-	clk = devm_clk_register(dev->dev, &lvds_pll->pll_hw);
-	if (IS_ERR(clk)) {
-		ret = PTR_ERR(clk);
-		goto fail;
+	ret = devm_clk_hw_register(dev->dev, &lvds_pll->pll_hw);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ret = devm_of_clk_add_hw_provider(dev->dev, of_clk_hw_simple_get, &lvds_pll->pll_hw);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return &lvds_pll->pll_hw;
+}
+
+struct clk *mpd4_get_lcdc_clock(struct drm_device *dev)
+{
+	struct clk_hw *hw;
+	struct clk *clk;
+
+
+	/* TODO: do we need different pll in other cases? */
+	hw = mpd4_lvds_pll_init(dev);
+	if (IS_ERR(hw)) {
+		DRM_DEV_ERROR(dev->dev, "failed to register LVDS PLL\n");
+		return ERR_CAST(hw);
 	}
 
-	return clk;
+	clk = devm_clk_get(dev->dev, "lcdc_clk");
+	if (clk == ERR_PTR(-ENOENT)) {
+		drm_warn(dev, "can't get LCDC clock, using PLL directly\n");
 
-fail:
-	return ERR_PTR(ret);
+		return devm_clk_hw_get_clk(dev->dev, hw, "lcdc_clk");
+	}
+
+	return clk;
 }

-- 
2.39.5