From: Weiyi Lu <weiyi.lu@mediatek.com>
To: Nicolas Boichat <drinkcat@chromium.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
Rob Herring <robh@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
James Liao <jamesjj.liao@mediatek.com>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>, <linux-clk@vger.kernel.org>,
srv_heupstream <srv_heupstream@mediatek.com>,
Wendell Lin <wendell.lin@mediatek.com>
Subject: Re: [PATCH v2 3/5] clk: mediatek: Fix asymmetrical PLL enable and disable control
Date: Tue, 11 Aug 2020 14:34:46 +0800 [thread overview]
Message-ID: <1597127686.20627.8.camel@mtksdaap41> (raw)
In-Reply-To: <CANMq1KAYg2+RQiF0w7-2FKZj1QwoPDsXtmak-DHfserRjX-TWA@mail.gmail.com>
On Wed, 2020-07-29 at 19:02 +0800, Nicolas Boichat wrote:
> On Wed, Jul 29, 2020 at 6:51 PM Nicolas Boichat <drinkcat@chromium.org> wrote:
> >
> > On Wed, Jul 29, 2020 at 4:44 PM Weiyi Lu <weiyi.lu@mediatek.com> wrote:
> > >
> > > The en_mask actually is a combination of divider enable mask
> > > and pll enable bit(bit0).
> > > Before this patch, we enabled both divider mask and bit0 in prepare(),
> > > but only cleared the bit0 in unprepare().
> > > Now, setting the enable register(CON0) in 2 steps: first divider mask,
> > > then bit0 during prepare(), vice versa.
> > > Hence, en_mask will only be used as divider enable mask.
> > > Meanwhile, all the SoC PLL data are updated.
> >
> > I like this a lot better, most changes look fine, just a few nits.
> >
> > >
> > > Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
> > > ---
> > > drivers/clk/mediatek/clk-mt2701.c | 26 ++++++++++++------------
> > > drivers/clk/mediatek/clk-mt2712.c | 30 ++++++++++++++--------------
> > > drivers/clk/mediatek/clk-mt6765.c | 20 +++++++++----------
> > > drivers/clk/mediatek/clk-mt6779.c | 24 +++++++++++-----------
> > > drivers/clk/mediatek/clk-mt6797.c | 20 +++++++++----------
> > > drivers/clk/mediatek/clk-mt7622.c | 18 ++++++++---------
> > > drivers/clk/mediatek/clk-mt7629.c | 12 +++++------
> > > drivers/clk/mediatek/clk-mt8173.c | 42 ++++++++++++++++++++++++++-------------
> > > drivers/clk/mediatek/clk-mt8183.c | 22 ++++++++++----------
> > > drivers/clk/mediatek/clk-pll.c | 10 ++++++++--
> > > 10 files changed, 122 insertions(+), 102 deletions(-)
> > >
> [snip]
> > > diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c
> > > index f440f2cd..3c79e1a 100644
> > > --- a/drivers/clk/mediatek/clk-pll.c
> > > +++ b/drivers/clk/mediatek/clk-pll.c
> > > @@ -247,8 +247,10 @@ static int mtk_pll_prepare(struct clk_hw *hw)
> > > writel(r, pll->pwr_addr);
> > > udelay(1);
> > >
> > > - r = readl(pll->base_addr + REG_CON0);
> > > - r |= pll->data->en_mask;
> > > + r = readl(pll->base_addr + REG_CON0) | CON0_BASE_EN;
> > > + writel(r, pll->base_addr + REG_CON0);
> > > +
> > > + r = readl(pll->base_addr + REG_CON0) | pll->data->en_mask;
>
> One more question. I have the feeling that CON0_BASE_EN is what
> enables the clock for good (and pll->data->en_mask is just an
> additional setting/mask, since you could disable the clock by simply
> clearing CON0_BASE_EN). Shouldn't you set pll->data->en_mask _first_,
> then CON0_BASE_EN?
>
Hi Nicolas,
Actually I had the same question when I first saw it.
But this is the recommended sequence in the PLL application notes.
preapre
{
| CON0_BASE_EN;
| pll->data->en_mask;
}
unprepare
{
~pll->data->en_mask;
~CON0_BASE_EN;
}
> > > writel(r, pll->base_addr + REG_CON0);
> >
> > As a small optimization, you can do:
> >
> > if (pll->data->en_mask) {
> > r = readl(pll->base_addr + REG_CON0) | pll->data->en_mask;
> > writel(r, pll->base_addr + REG_CON0);
> > }
> >
> > >
> > > __mtk_pll_tuner_enable(pll);
> > > @@ -278,6 +280,10 @@ static void mtk_pll_unprepare(struct clk_hw *hw)
> > > __mtk_pll_tuner_disable(pll);
> > >
> > > r = readl(pll->base_addr + REG_CON0);
> > > + r &= ~pll->data->en_mask;
> >
> > Move this to one line? (so that the code looks symmetrical, too?)
> >
> > > + writel(r, pll->base_addr + REG_CON0);
> > > +
> > > + r = readl(pll->base_addr + REG_CON0);
> > > r &= ~CON0_BASE_EN;
>
> And ditto, ~CON0_BASE_EN then ~pll->data->en_mask?
>
> >
> > ditto?
> >
> > > writel(r, pll->base_addr + REG_CON0);
> > >
> > > --
> > > 1.8.1.1.dirty
next prev parent reply other threads:[~2020-08-11 6:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 8:44 [PATCH v2 0/5] Mediatek MT8192 clock support Weiyi Lu
2020-07-29 8:44 ` [PATCH v2 1/5] dt-bindings: ARM: Mediatek: Document bindings for MT8192 Weiyi Lu
2020-07-29 9:53 ` Enric Balletbo Serra
2020-08-11 7:01 ` Weiyi Lu
2020-07-29 8:44 ` [PATCH v2 2/5] clk: mediatek: Add dt-bindings for MT8192 clocks Weiyi Lu
2020-07-29 8:44 ` [PATCH v2 3/5] clk: mediatek: Fix asymmetrical PLL enable and disable control Weiyi Lu
2020-07-29 10:51 ` Nicolas Boichat
2020-07-29 11:02 ` Nicolas Boichat
2020-08-11 6:34 ` Weiyi Lu [this message]
2020-08-11 6:50 ` Weiyi Lu
2020-07-29 8:44 ` [PATCH v2 4/5] clk: mediatek: Add configurable enable control to mtk_pll_data Weiyi Lu
2020-07-29 10:58 ` Nicolas Boichat
2020-08-11 6:43 ` Weiyi Lu
2020-08-11 7:28 ` Nicolas Boichat
2020-08-11 9:31 ` Weiyi Lu
[not found] ` <1596012277-8448-6-git-send-email-weiyi.lu@mediatek.com>
2020-07-29 9:32 ` [PATCH v2 5/5] clk: mediatek: Add MT8192 clock support Enric Balletbo Serra
2020-08-11 7:03 ` Weiyi Lu
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