linux-kernel - [PATCH v6 1/6] clk: Ingenic: Remove unnecessary spinlock when reading registers.

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Message-Id: <1584865262-25297-3-git-send-email-zhouyanjie@wanyeetech.com>
Date:   Sun, 22 Mar 2020 16:20:57 +0800
From:   周琰杰 (Zhou Yanjie) 
        <zhouyanjie@...yeetech.com>
To:     linux-clk@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        sboyd@...nel.org, mturquette@...libre.com, robh+dt@...nel.org,
        mark.rutland@....com, paul@...pouillou.net,
        dongsheng.qiu@...enic.com, yanfei.li@...enic.com,
        sernia.zhou@...mail.com, zhenwenjin@...il.com
Subject: [PATCH v6 1/6] clk: Ingenic: Remove unnecessary spinlock when reading registers.

It is not necessary to use spinlock when reading registers,
so remove it from cgu.c.

Suggested-by: Paul Cercueil <paul@...pouillou.net>
Suggested-by: Paul Burton <paulburton@...nel.org>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
---

Notes:
    v2:
    New patch.
    
    v2->v3:
    Adjust order from [5/5] in v2 to [1/5] in v3.
    
    v3->v4:
    Remove the spinlock around ingenic_cgu_gate_get().
    
    v4->v5:
    Rebase on top of kernel 5.6-rc1.
    
    v5->v6:
    No change.

 drivers/clk/ingenic/cgu.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
index 6e96303..ab1302a 100644
--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -76,16 +76,13 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	const struct ingenic_cgu_pll_info *pll_info;
 	unsigned m, n, od_enc, od;
 	bool bypass;
-	unsigned long flags;
 	u32 ctl;
 
 	clk_info = &cgu->clock_info[ingenic_clk->idx];
 	BUG_ON(clk_info->type != CGU_CLK_PLL);
 	pll_info = &clk_info->pll;
 
-	spin_lock_irqsave(&cgu->lock, flags);
 	ctl = readl(cgu->base + pll_info->reg);
-	spin_unlock_irqrestore(&cgu->lock, flags);
 
 	m = (ctl >> pll_info->m_shift) & GENMASK(pll_info->m_bits - 1, 0);
 	m += pll_info->m_offset;
@@ -259,12 +256,9 @@ static int ingenic_pll_is_enabled(struct clk_hw *hw)
 	struct ingenic_cgu *cgu = ingenic_clk->cgu;
 	const struct ingenic_cgu_clk_info *clk_info = to_clk_info(ingenic_clk);
 	const struct ingenic_cgu_pll_info *pll_info = &clk_info->pll;
-	unsigned long flags;
 	u32 ctl;
 
-	spin_lock_irqsave(&cgu->lock, flags);
 	ctl = readl(cgu->base + pll_info->reg);
-	spin_unlock_irqrestore(&cgu->lock, flags);
 
 	return !!(ctl & BIT(pll_info->enable_bit));
 }
@@ -562,16 +556,12 @@ static int ingenic_clk_is_enabled(struct clk_hw *hw)
 	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
 	struct ingenic_cgu *cgu = ingenic_clk->cgu;
 	const struct ingenic_cgu_clk_info *clk_info;
-	unsigned long flags;
 	int enabled = 1;
 
 	clk_info = &cgu->clock_info[ingenic_clk->idx];
 
-	if (clk_info->type & CGU_CLK_GATE) {
-		spin_lock_irqsave(&cgu->lock, flags);
+	if (clk_info->type & CGU_CLK_GATE)
 		enabled = !ingenic_cgu_gate_get(cgu, &clk_info->gate);
-		spin_unlock_irqrestore(&cgu->lock, flags);
-	}
 
 	return enabled;
 }
-- 
2.7.4