linux-kernel - Re: [PATCH v5 2/9] clk: mediatek: Add new clkmux register API

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Message-ID: <155501357547.20095.14128079106803580356@swboyd.mtv.corp.google.com>
Date:   Thu, 11 Apr 2019 13:12:55 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Nicolas Boichat <drinkcat@...omium.org>,
        Weiyi Lu <weiyi.lu@...iatek.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh@...nel.org>,
        James Liao <jamesjj.liao@...iatek.com>,
        Fan Chen <fan.chen@...iatek.com>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>, linux-clk@...r.kernel.org,
        srv_heupstream <srv_heupstream@...iatek.com>,
        stable@...r.kernel.org, Owen Chen <owen.chen@...iatek.com>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v5 2/9] clk: mediatek: Add new clkmux register API

(Please trim replies to save me time)

Quoting Nicolas Boichat (2019-03-14 16:21:26)
> On Tue, Mar 5, 2019 at 1:06 PM Weiyi Lu <weiyi.lu@...iatek.com> wrote:
> > +static u8 mtk_clk_mux_get_parent(struct clk_hw *hw)
> > +{
> > +       struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> > +       u32 mask = GENMASK(mux->data->mux_width - 1, 0);
> > +       u32 val;
> > +
> > +       regmap_read(mux->regmap, mux->data->mux_ofs, &val);
> > +       val = (val >> mux->data->mux_shift) & mask;
> > +
> > +       return val;
> > +}
> > +
> > +static int mtk_clk_mux_set_parent_lock(struct clk_hw *hw, u8 index)
> > +{
> > +       struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> > +       u32 mask = GENMASK(mux->data->mux_width - 1, 0);
> > +       unsigned long flags;
> 
> Guenter reported the following issue
> (https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1524422):
> ""
> The construct conditionally acquiring a spinlock is too complex for
> gcc to understand. This results in the following build warning.
> 
> drivers/clk/mediatek/clk-mux.c: In function
> 'mtk_clk_mux_set_parent_lock': ./include/linux/spinlock.h:279:3:
> warning: 'flags' may be used uninitialized in this function
> 
> Other clock drivers avoid the problem by initializing flags with 0.
> Lets do that here as well.
> """

Ok. I'll squash in this fix.

diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c
index 877a883fa616..76f9cd039195 100644
--- a/drivers/clk/mediatek/clk-mux.c
+++ b/drivers/clk/mediatek/clk-mux.c
@@ -76,7 +76,7 @@ static int mtk_clk_mux_set_parent_lock(struct clk_hw *hw, u8 index)
 {
 	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
 	u32 mask = GENMASK(mux->data->mux_width - 1, 0);
-	unsigned long flags;
+	unsigned long flags = 0;
 
 	if (mux->lock)
 		spin_lock_irqsave(mux->lock, flags);
@@ -99,7 +99,7 @@ static int mtk_clk_mux_set_parent_setclr_lock(struct clk_hw *hw, u8 index)
 	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
 	u32 mask = GENMASK(mux->data->mux_width - 1, 0);
 	u32 val, orig;
-	unsigned long flags;
+	unsigned long flags = 0;
 
 	if (mux->lock)
 		spin_lock_irqsave(mux->lock, flags);