linux-kernel - [PATCH v5 9/9] clk: mediatek: Allow changing PLL rate when it is off

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Date:   Tue, 5 Mar 2019 13:05:46 +0800
From:   Weiyi Lu <weiyi.lu@...iatek.com>
To:     Nicolas Boichat <drinkcat@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh@...nel.org>
CC:     James Liao <jamesjj.liao@...iatek.com>,
        Fan Chen <fan.chen@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <linux-clk@...r.kernel.org>,
        <srv_heupstream@...iatek.com>, <stable@...r.kernel.org>,
        Weiyi Lu <weiyi.lu@...iatek.com>
Subject: [PATCH v5 9/9] clk: mediatek: Allow changing PLL rate when it is off

From: James Liao <jamesjj.liao@...iatek.com>

Some modules may need to change its clock rate before turn on it.
So changing PLL's rate when it is off should be allowed.
This patch removes PLL enabled check before set rate, so that
PLLs can set new frequency even if they are off.

On MT8173 for example, ARMPLL's enable bit can be controlled by
other HW. That means ARMPLL may be turned on even if we (CPU / SW)
set ARMPLL's enable bit as 0. In this case, SW may want and can
still change ARMPLL's rate by changing its pcw and postdiv settings.
But without this patch, new pcw setting will not be applied because
its enable bit is 0.

Signed-off-by: James Liao <jamesjj.liao@...iatek.com>
Acked-by: Michael Turquette <mturuqette@...libre.com>
Signed-off-by: Weiyi Lu <weiyi.lu@...iatek.com>
---
 drivers/clk/mediatek/clk-pll.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c
index 65cee1d6c400..8d556fc99fed 100644
--- a/drivers/clk/mediatek/clk-pll.c
+++ b/drivers/clk/mediatek/clk-pll.c
@@ -124,9 +124,6 @@ static void mtk_pll_set_rate_regs(struct mtk_clk_pll *pll, u32 pcw,
 		int postdiv)
 {
 	u32 chg, val;
-	int pll_en;
-
-	pll_en = readl(pll->base_addr + REG_CON0) & CON0_BASE_EN;
 
 	/* disable tuner */
 	__mtk_pll_tuner_disable(pll);
@@ -147,12 +144,7 @@ static void mtk_pll_set_rate_regs(struct mtk_clk_pll *pll, u32 pcw,
 			pll->data->pcw_shift);
 	val |= pcw << pll->data->pcw_shift;
 	writel(val, pll->pcw_addr);
-
-	chg = readl(pll->pcw_chg_addr);
-
-	if (pll_en)
-		chg |= PCW_CHG_MASK;
-
+	chg = readl(pll->pcw_chg_addr) | PCW_CHG_MASK;
 	writel(chg, pll->pcw_chg_addr);
 	if (pll->tuner_addr)
 		writel(val + 1, pll->tuner_addr);
@@ -160,8 +152,7 @@ static void mtk_pll_set_rate_regs(struct mtk_clk_pll *pll, u32 pcw,
 	/* restore tuner_en */
 	__mtk_pll_tuner_enable(pll);
 
-	if (pll_en)
-		udelay(20);
+	udelay(20);
 }
 
 /*
-- 
2.18.0