drm/msm/dsi: Save/Restore PLL status across PHY reset

index e18872a..912057d 100644
@@ -95,6 +95,8 @@ struct msm_dsi_pll *msm_dsi_pll_init(struct platform_device *pdev,
 void msm_dsi_pll_destroy(struct msm_dsi_pll *pll);
 int msm_dsi_pll_get_clk_provider(struct msm_dsi_pll *pll,
 	struct clk **byte_clk_provider, struct clk **pixel_clk_provider);
+void msm_dsi_pll_save_state(struct msm_dsi_pll *pll);
+int msm_dsi_pll_restore_state(struct msm_dsi_pll *pll);
 #else
 static inline struct msm_dsi_pll *msm_dsi_pll_init(struct platform_device *pdev,
 			 enum msm_dsi_phy_type type, int id) {

@@ -108,6 +110,13 @@ static inline int msm_dsi_pll_get_clk_provider(struct msm_dsi_pll *pll,
 {
 	return -ENODEV;
 }
+static inline void msm_dsi_pll_save_state(struct msm_dsi_pll *pll)
+{
+}
+static inline int msm_dsi_pll_restore_state(struct msm_dsi_pll *pll)
+{
+	return 0;
+}
 #endif
 
 /* dsi host */

index bd247b7..ca4ff4a 100644
@@ -611,12 +611,28 @@ int msm_dsi_manager_phy_enable(int id,
 	struct msm_dsi *msm_dsi = dsi_mgr_get_dsi(id);
 	struct msm_dsi_phy *phy = msm_dsi->phy;
 	int src_pll_id = IS_DUAL_DSI() ? DSI_CLOCK_MASTER : id;
+	struct msm_dsi_pll *pll = msm_dsi_phy_get_pll(msm_dsi->phy);
 	int ret;
 
 	ret = msm_dsi_phy_enable(phy, src_pll_id, bit_rate, esc_rate);
 	if (ret)
 		return ret;
 
+	/*
+	 * Reset DSI PHY silently changes its PLL registers to reset status,
+	 * which will confuse clock driver and result in wrong output rate of
+	 * link clocks. Restore PLL status if its PLL is being used as clock
+	 * source.
+	 */
+	if (!IS_DUAL_DSI() || (id == DSI_CLOCK_MASTER)) {
+		ret = msm_dsi_pll_restore_state(pll);
+		if (ret) {
+			pr_err("%s: failed to restore pll state\n", __func__);
+			msm_dsi_phy_disable(phy);
+			return ret;
+		}
+	}
+
 	msm_dsi->phy_enabled = true;
 	msm_dsi_phy_get_clk_pre_post(phy, clk_pre, clk_post);
 

@@ -629,6 +645,11 @@ void msm_dsi_manager_phy_disable(int id)
 	struct msm_dsi *mdsi = dsi_mgr_get_dsi(DSI_CLOCK_MASTER);
 	struct msm_dsi *sdsi = dsi_mgr_get_dsi(DSI_CLOCK_SLAVE);
 	struct msm_dsi_phy *phy = msm_dsi->phy;
+	struct msm_dsi_pll *pll = msm_dsi_phy_get_pll(msm_dsi->phy);
+
+	/* Save PLL status if it is a clock source */
+	if (!IS_DUAL_DSI() || (id == DSI_CLOCK_MASTER))
+		msm_dsi_pll_save_state(pll);
 
 	/* disable DSI phy
 	 * In dual-dsi configuration, the phy should be disabled for the

61 lines not on this page · raw message

index 5a3bb241..b69df19 100644
@@ -27,6 +27,7 @@ struct msm_dsi_pll {
 
 	struct clk_hw	clk_hw;
 	bool		pll_on;
+	bool		state_saved;
 
 	unsigned long	min_rate;
 	unsigned long	max_rate;

index eb8ac30..1912cfc 100644
@@ -465,26 +465,21 @@ static int dsi_pll_28nm_restore_state(struct msm_dsi_pll *pll)
 	void __iomem *base = pll_28nm->mmio;
 	int ret;
 
-	if ((cached_state->vco_rate != 0) &&
-		(cached_state->vco_rate == __clk_get_rate(pll->clk_hw.clk))) {
-		ret = dsi_pll_28nm_clk_set_rate(&pll->clk_hw,
-						cached_state->vco_rate, 0);
-		if (ret) {
-			dev_err(&pll_28nm->pdev->dev,
-				"restore vco rate failed. ret=%d\n", ret);
-			return ret;
-		}
-
-		pll_write(base + REG_DSI_28nm_PHY_PLL_POSTDIV3_CFG,
-				cached_state->postdiv3);
-		pll_write(base + REG_DSI_28nm_PHY_PLL_POSTDIV1_CFG,
-				cached_state->postdiv1);
-		pll_write(base + REG_DSI_28nm_PHY_PLL_VREG_CFG,
-				cached_state->byte_mux);
-
-		cached_state->vco_rate = 0;
+	ret = dsi_pll_28nm_clk_set_rate(&pll->clk_hw,
+					cached_state->vco_rate, 0);
+	if (ret) {
+		dev_err(&pll_28nm->pdev->dev,
+			"restore vco rate failed. ret=%d\n", ret);
+		return ret;
 	}
 
+	pll_write(base + REG_DSI_28nm_PHY_PLL_POSTDIV3_CFG,
+			cached_state->postdiv3);
+	pll_write(base + REG_DSI_28nm_PHY_PLL_POSTDIV1_CFG,
+			cached_state->postdiv1);
+	pll_write(base + REG_DSI_28nm_PHY_PLL_VREG_CFG,
+			cached_state->byte_mux);
+
 	return 0;
 }