Re: [PATCH v4 01/12] clk: mediatek: Disable tuner_en before change PLL rate

Weiyi Lu
2019-02-27T04:39:31Z

On Wed, 2019-02-27 at 11:51 +0800, Weiyi Lu wrote:
> On Tue, 2019-02-26 at 16:59 +0100, Matthias Brugger wrote:
> >
> > On 01/02/2019 09:30, Weiyi Lu wrote:
> > > From: Owen Chen <owen.chen@mediatek.com>
> > >
> > > PLLs with tuner_en bit, such as APLL1, need to disable
> > > tuner_en before apply new frequency settings, or the new frequency
> > > settings (pcw) will not be applied.
> > > The tuner_en bit will be disabled during changing PLL rate
> > > and be restored after new settings applied.
> > > Another minor change is to correct the macro name of pcw change bit
> > > to CON1_PCW_CHG because PCW_CHG(BIT31) is on CON1.
> > >
> > > Fixes: e2f744a82d725 (clk: mediatek: Add MT2712 clock support)
> > > Cc: <stable@vger.kernel.org>
> > > Signed-off-by: Owen Chen <owen.chen@mediatek.com>
> > > ---
> > > drivers/clk/mediatek/clk-pll.c | 33 +++++++++++++++++++++++++++++++--
> > > 1 file changed, 31 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c
> > > index f54e4015b0b1..f0ff5f535c7e 100644
> > > --- a/drivers/clk/mediatek/clk-pll.c
> > > +++ b/drivers/clk/mediatek/clk-pll.c
> > > @@ -27,7 +27,7 @@
> > > #define CON0_BASE_EN BIT(0)
> > > #define CON0_PWR_ON BIT(0)
> > > #define CON0_ISO_EN BIT(1)
> > > -#define CON0_PCW_CHG BIT(31)
> > > +#define CON1_PCW_CHG BIT(31)
> > >
> > > #define AUDPLL_TUNER_EN BIT(31)
> > >
> > > @@ -93,9 +93,31 @@ static void mtk_pll_set_rate_regs(struct mtk_clk_pll *pll, u32 pcw,
> > > {
> > > u32 con1, val;
> > > int pll_en;
> > > + u32 tuner_en = 0;
> > > + u32 tuner_en_mask;
> > > + void __iomem *tuner_en_addr = NULL;
> > >
> > > pll_en = readl(pll->base_addr + REG_CON0) & CON0_BASE_EN;
> > >
> > > + /* disable tuner */
> > > + if (pll->tuner_en_addr) {
> > > + tuner_en_addr = pll->tuner_en_addr;
> > > + tuner_en_mask = BIT(pll->data->tuner_en_bit);
> > > + } else if (pll->tuner_addr) {
> > > + tuner_en_addr = pll->tuner_addr;
> > > + tuner_en_mask = AUDPLL_TUNER_EN;
> > > + }
> > > +
> > > + if (tuner_en_addr) {
> > > + val = readl(tuner_en_addr);
> > > + tuner_en = val & tuner_en_mask;
> > > +
> > > + if (tuner_en) {
> > > + val &= ~tuner_en_mask;
> > > + writel(val, tuner_en_addr);
> > > + }
> > > + }
> > > +
> >
> > Why don't we use a flag here, it would make the code easier to understand.
> > I think it would also help if you put this code in a separate function.
> >
> > Regards,
> > Matthias
> >
>
> Hi Matthias,
>
> I guess you suggest to add a flag (e.g. CLK_TUNER_SUPPORT) and declare
> the PLL clock with this flag. And inside this mtk_pll_set_rate_regs()
> function, we could modify it as below. Am I right?
>
> if (pll->data->flags & CLK_TUNER_SUPPORT)
> disable_tuner();
> [...]
> if (pll->data->flags & CLK_TUNER_SUPPORT)
> enable_tuner();
>
>
> But I thought this flag might be a customized flags and can only be put
> in clk-mtk.h not clk-provider.h so far. And it might cause
> potential problem of clock flag re-definition. May I have more
> suggestion?
>

Please ignore the potential problem I mentioned, I just checked it
carefully and that redefinition problem won't happen in current flow.
Sorry for having you confused.
But I still need to confirm with you if the method in previous mail is
correct? Thanks.

> >
> > > /* set postdiv */
> > > val = readl(pll->pd_addr);
> > > val &= ~(POSTDIV_MASK << pll->data->pd_shift);
> > > @@ -116,12 +138,19 @@ static void mtk_pll_set_rate_regs(struct mtk_clk_pll *pll, u32 pcw,
> > > con1 = readl(pll->base_addr + REG_CON1);
> > >
> > > if (pll_en)
> > > - con1 |= CON0_PCW_CHG;
> > > + con1 |= CON1_PCW_CHG;
> > >
> > > writel(con1, pll->base_addr + REG_CON1);
> > > if (pll->tuner_addr)
> > > writel(con1 + 1, pll->tuner_addr);
> > >
> > > + /* restore tuner_en */
> > > + if (tuner_en_addr && tuner_en) {
> > > + val = readl(tuner_en_addr);
> > > + val |= tuner_en_mask;
> > > + writel(val, tuner_en_addr);
> > > + }
> > > +
> > > if (pll_en)
> > > udelay(20);
> > > }
> > >
>