drm/rockchip: vop2: Improve display modes handling on RK3588 HDMI0

[ Upstream commit 2c1268e ]

The RK3588 specific implementation is currently quite limited in terms
of handling the full range of display modes supported by the connected
screens, e.g. 2560x1440@75Hz, 2048x1152@60Hz, 1024x768@60Hz are just a
few of them.

Additionally, it doesn't cope well with non-integer refresh rates like
59.94, 29.97, 23.98, etc.

Make use of HDMI0 PHY PLL as a more accurate DCLK source to handle
all display modes up to 4K@60Hz.

Tested-by: FUKAUMI Naoki <[email protected]>
Signed-off-by: Cristian Ciocaltea <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Sasha Levin <[email protected]>

Author: cristicc

drivers/gpu/drm/rockchip/rockchip_drm_vop2.c

@@ -157,6 +157,7 @@ struct vop2_video_port {
 	struct drm_crtc crtc;
 	struct vop2 *vop2;
 	struct clk *dclk;
+	struct clk *dclk_src;
 	unsigned int id;
 	const struct vop2_video_port_data *data;
 
@@ -211,6 +212,7 @@ struct vop2 {
 	struct clk *hclk;
 	struct clk *aclk;
 	struct clk *pclk;
+	struct clk *pll_hdmiphy0;
 
 	/* optional internal rgb encoder */
 	struct rockchip_rgb *rgb;
@@ -219,6 +221,8 @@ struct vop2 {
 	struct vop2_win win[];
 };
 
+#define VOP2_MAX_DCLK_RATE		600000000
+
 #define vop2_output_if_is_hdmi(x)	((x) == ROCKCHIP_VOP2_EP_HDMI0 || \
 					 (x) == ROCKCHIP_VOP2_EP_HDMI1)
 
@@ -1051,6 +1055,9 @@ static void vop2_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	vop2_crtc_disable_irq(vp, VP_INT_DSP_HOLD_VALID);
 
+	if (vp->dclk_src)
+		clk_set_parent(vp->dclk, vp->dclk_src);
+
 	clk_disable_unprepare(vp->dclk);
 
 	vop2->enable_count--;
@@ -2071,6 +2078,27 @@ static void vop2_crtc_atomic_enable(struct drm_crtc *crtc,
 
 	vop2_vp_write(vp, RK3568_VP_MIPI_CTRL, 0);
 
+	/*
+	 * Switch to HDMI PHY PLL as DCLK source for display modes up
+	 * to 4K@60Hz, if available, otherwise keep using the system CRU.
+	 */
+	if (vop2->pll_hdmiphy0 && clock <= VOP2_MAX_DCLK_RATE) {
+		drm_for_each_encoder_mask(encoder, crtc->dev, crtc_state->encoder_mask) {
+			struct rockchip_encoder *rkencoder = to_rockchip_encoder(encoder);
+
+			if (rkencoder->crtc_endpoint_id == ROCKCHIP_VOP2_EP_HDMI0) {
+				if (!vp->dclk_src)
+					vp->dclk_src = clk_get_parent(vp->dclk);
+
+				ret = clk_set_parent(vp->dclk, vop2->pll_hdmiphy0);
+				if (ret < 0)
+					drm_warn(vop2->drm,
+						 "Could not switch to HDMI0 PHY PLL: %d\n", ret);
+				break;
+			}
+		}
+	}
+
 	clk_set_rate(vp->dclk, clock);
 
 	vop2_post_config(crtc);
@@ -3242,6 +3270,12 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 		return PTR_ERR(vop2->pclk);
 	}
 
+	vop2->pll_hdmiphy0 = devm_clk_get_optional(vop2->dev, "pll_hdmiphy0");
+	if (IS_ERR(vop2->pll_hdmiphy0)) {
+		drm_err(vop2->drm, "failed to get pll_hdmiphy0\n");
+		return PTR_ERR(vop2->pll_hdmiphy0);
+	}
+
 	vop2->irq = platform_get_irq(pdev, 0);
 	if (vop2->irq < 0) {
 		drm_err(vop2->drm, "cannot find irq for vop2\n");