linux-kernel - Re: [PATCH v2 3/4] clk: qcom: Add support for controlling Fabia PLL

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Message-ID: <152150242792.254778.8044280968962039576@swboyd.mtv.corp.google.com>
Date:   Mon, 19 Mar 2018 16:33:47 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Amit Nischal <anischal@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Odelu Kukatla <okukatla@...eaurora.org>,
        Taniya Das <tdas@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Amit Nischal <anischal@...eaurora.org>
Subject: Re: [PATCH v2 3/4] clk: qcom: Add support for controlling Fabia PLL

Quoting Amit Nischal (2018-03-07 23:18:14)
> Fabia PLL is a Digital Frequency Locked Loop (DFLL) clock
> generator which has a wide range of frequency output. It
> supports dynamic updating of the output frequency
> ("frequency slewing") without need to turn off the PLL
> before configuration. Add support for initial configuration
> and programming sequence to control fabia PLLs.
> 
> Signed-off-by: Amit Nischal <anischal@...eaurora.org>
> ---

Applied to clk-next with a little adjustment below:


diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index e6b8d62e5175..9722b701fbdb 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -891,8 +891,9 @@ static int alpha_pll_fabia_enable(struct clk_hw *hw)
 	int ret;
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 val, opmode_val;
+	struct regmap *regmap = pll->clkr.regmap;
 
-	ret = regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
+	ret = regmap_read(regmap, PLL_MODE(pll), &val);
 	if (ret)
 		return ret;
 
@@ -904,8 +905,7 @@ static int alpha_pll_fabia_enable(struct clk_hw *hw)
 		return wait_for_pll_enable_active(pll);
 	}
 
-	/* Read opmode value */
-	ret = regmap_read(pll->clkr.regmap, PLL_OPMODE(pll), &opmode_val);
+	ret = regmap_read(regmap, PLL_OPMODE(pll), &opmode_val);
 	if (ret)
 		return ret;
 
@@ -913,30 +913,20 @@ static int alpha_pll_fabia_enable(struct clk_hw *hw)
 	if ((opmode_val & FABIA_OPMODE_RUN) && (val & PLL_OUTCTRL))
 		return 0;
 
-	/* Disable PLL output */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
-							PLL_OUTCTRL, 0);
+	ret = regmap_update_bits(regmap, PLL_MODE(pll), PLL_OUTCTRL, 0);
 	if (ret)
 		return ret;
 
-	/* Set Operation mode to STANBY */
-	ret = regmap_write(pll->clkr.regmap, PLL_OPMODE(pll),
-							FABIA_OPMODE_STANDBY);
+	ret = regmap_write(regmap, PLL_OPMODE(pll), FABIA_OPMODE_STANDBY);
 	if (ret)
 		return ret;
 
-	/* PLL should be in STANDBY mode before continuing */
-	mb();
-
-	/* Bring PLL out of reset */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
-						PLL_RESET_N, PLL_RESET_N);
+	ret = regmap_update_bits(regmap, PLL_MODE(pll), PLL_RESET_N,
+				 PLL_RESET_N);
 	if (ret)
 		return ret;
 
-	/* Set Operation mode to RUN */
-	ret = regmap_write(pll->clkr.regmap, PLL_OPMODE(pll),
-							FABIA_OPMODE_RUN);
+	ret = regmap_write(regmap, PLL_OPMODE(pll), FABIA_OPMODE_RUN);
 	if (ret)
 		return ret;
 
@@ -944,22 +934,13 @@ static int alpha_pll_fabia_enable(struct clk_hw *hw)
 	if (ret)
 		return ret;
 
-	/* Enable the main PLL output */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll),
-				FABIA_PLL_OUT_MASK, FABIA_PLL_OUT_MASK);
-	if (ret)
-		return ret;
-
-	/* Enable PLL outputs */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
-						PLL_OUTCTRL, PLL_OUTCTRL);
+	ret = regmap_update_bits(regmap, PLL_USER_CTL(pll),
+				 FABIA_PLL_OUT_MASK, FABIA_PLL_OUT_MASK);
 	if (ret)
 		return ret;
 
-	/* Ensure that the write above goes through before returning. */
-	mb();
-
-	return ret;
+	return regmap_update_bits(regmap, PLL_MODE(pll), PLL_OUTCTRL,
+				 PLL_OUTCTRL);
 }
 
 static void alpha_pll_fabia_disable(struct clk_hw *hw)
@@ -967,8 +948,9 @@ static void alpha_pll_fabia_disable(struct clk_hw *hw)
 	int ret;
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 val;
+	struct regmap *regmap = pll->clkr.regmap;
 
-	ret = regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
+	ret = regmap_read(regmap, PLL_MODE(pll), &val);
 	if (ret)
 		return;
 
@@ -978,23 +960,18 @@ static void alpha_pll_fabia_disable(struct clk_hw *hw)
 		return;
 	}
 
-	/* Disable PLL outputs */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
-							PLL_OUTCTRL, 0);
+	ret = regmap_update_bits(regmap, PLL_MODE(pll), PLL_OUTCTRL, 0);
 	if (ret)
 		return;
 
 	/* Disable main outputs */
-	ret = regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll),
-							FABIA_PLL_OUT_MASK, 0);
+	ret = regmap_update_bits(regmap, PLL_USER_CTL(pll), FABIA_PLL_OUT_MASK,
+				 0);
 	if (ret)
 		return;
 
 	/* Place the PLL in STANDBY */
-	ret = regmap_write(pll->clkr.regmap, PLL_OPMODE(pll),
-							FABIA_OPMODE_STANDBY);
-	if (ret)
-		return;
+	regmap_write(regmap, PLL_OPMODE(pll), FABIA_OPMODE_STANDBY);
 }
 
 static unsigned long alpha_pll_fabia_recalc_rate(struct clk_hw *hw,