linux-kernel - Re:[PATCH v4 4/4] drm/rockchip: vop2: Support setting custom background color

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Message-ID: <2750b73.10b0.19ba61052c8.Coremail.andyshrk@163.com>
Date: Sat, 10 Jan 2026 12:00:46 +0800 (CST)
From: "Andy Yan" <andyshrk@....com>
To: "Cristian Ciocaltea" <cristian.ciocaltea@...labora.com>
Cc: "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>,
	"Sandy Huang" <hjc@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	"Andy Yan" <andy.yan@...k-chips.com>,
	"Louis Chauvet" <louis.chauvet@...tlin.com>,
	"Haneen Mohammed" <hamohammed.sa@...il.com>,
	"Melissa Wen" <melissa.srw@...il.com>,
	"Robert Mader" <robert.mader@...labora.com>, kernel@...labora.com,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org
Subject: Re:[PATCH v4 4/4] drm/rockchip: vop2: Support setting custom
 background color



Hello Cristian,
At 2025-12-20 05:47:01, "Cristian Ciocaltea" <cristian.ciocaltea@...labora.com> wrote:
>The Rockchip VOP2 display controller allows configuring the background
>color of each video output port.
>
>Since a previous patch introduced the BACKGROUND_COLOR CRTC property,
>which defaults to solid black, make use of it when programming the
>hardware.
>
>Note the maximum precision allowed by the display controller is 10bpc,
>while the alpha component is not supported, hence ignored.
>
>Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
>---
> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 13 ++++++++++++-
> drivers/gpu/drm/rockchip/rockchip_drm_vop2.h |  4 ++++
> 2 files changed, 16 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>index 498df0ce4680..3a232d0d4acb 100644
>--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>@@ -1554,6 +1554,7 @@ static void vop2_post_config(struct drm_crtc *crtc)
> 	struct vop2_video_port *vp = to_vop2_video_port(crtc);
> 	struct vop2 *vop2 = vp->vop2;
> 	struct drm_display_mode *mode = &crtc->state->adjusted_mode;
>+	u64 bgcolor = crtc->state->background_color;
> 	u16 vtotal = mode->crtc_vtotal;
> 	u16 hdisplay = mode->crtc_hdisplay;
> 	u16 hact_st = mode->crtc_htotal - mode->crtc_hsync_start;
>@@ -1599,7 +1600,11 @@ static void vop2_post_config(struct drm_crtc *crtc)
> 		vop2_vp_write(vp, RK3568_VP_POST_DSP_VACT_INFO_F1, val);
> 	}
> 
>-	vop2_vp_write(vp, RK3568_VP_DSP_BG, 0);
>+	/* Background color is programmed with 10 bits of precision */
>+	val = FIELD_PREP(RK3568_VP_DSP_BG__DSP_BG_RED, DRM_ARGB64_GETR(bgcolor) >> 6);
>+	val |= FIELD_PREP(RK3568_VP_DSP_BG__DSP_BG_GREEN, DRM_ARGB64_GETG(bgcolor) >> 6);

>+	val |= FIELD_PREP(RK3568_VP_DSP_BG__DSP_BG_BLUE, DRM_ARGB64_GETB(bgcolor) >> 6);


        the bit31 of  RK3568_VP_DSP_BG  is bg_display_en， that means when we set a 
background color, we should set this bg_display_en bit.
       The default value of this bit is 1, which explains why the patch currently works properly even though it doesn't set bit31.

>+	vop2_vp_write(vp, RK3568_VP_DSP_BG, val);
> }
> 
> static int us_to_vertical_line(struct drm_display_mode *mode, int us)
>@@ -1984,6 +1989,10 @@ static int vop2_crtc_state_dump(struct drm_crtc *crtc, struct seq_file *s)
> 		   drm_get_bus_format_name(vcstate->bus_format));
> 	seq_printf(s, "\toutput_mode[%x]", vcstate->output_mode);
> 	seq_printf(s, " color_space[%d]\n", vcstate->color_space);
>+	seq_printf(s, "\tbackground color (10bpc): r=0x%x g=0x%x b=0x%x\n",
>+		   DRM_ARGB64_GETR(cstate->background_color) >> 6,
>+		   DRM_ARGB64_GETG(cstate->background_color) >> 6,
>+		   DRM_ARGB64_GETB(cstate->background_color) >> 6);
> 	seq_printf(s, "    Display mode: %dx%d%s%d\n",
> 		   mode->hdisplay, mode->vdisplay, interlaced ? "i" : "p",
> 		   drm_mode_vrefresh(mode));
>@@ -2473,6 +2482,8 @@ static int vop2_create_crtcs(struct vop2 *vop2)
> 			return dev_err_probe(drm->dev, ret,
> 					     "crtc init for video_port%d failed\n", i);
> 
>+		drm_crtc_attach_background_color_property(&vp->crtc);
>+
> 		drm_crtc_helper_add(&vp->crtc, &vop2_crtc_helper_funcs);
> 		if (vop2->lut_regs) {
> 			const struct vop2_video_port_data *vp_data = &vop2_data->vp[vp->id];
>diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
>index 9124191899ba..37722652844a 100644
>--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
>+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
>@@ -658,6 +658,10 @@ enum dst_factor_mode {
> #define RK3588_VP_CLK_CTRL__DCLK_OUT_DIV		GENMASK(3, 2)
> #define RK3588_VP_CLK_CTRL__DCLK_CORE_DIV		GENMASK(1, 0)
> 
>+#define RK3568_VP_DSP_BG__DSP_BG_RED			GENMASK(29, 20)
>+#define RK3568_VP_DSP_BG__DSP_BG_GREEN			GENMASK(19, 10)
>+#define RK3568_VP_DSP_BG__DSP_BG_BLUE			GENMASK(9, 0)
>+
> #define RK3568_VP_POST_SCL_CTRL__VSCALEDOWN		BIT(1)
> #define RK3568_VP_POST_SCL_CTRL__HSCALEDOWN		BIT(0)
> 
>
>-- 
>2.51.2