linux-kernel - Re: [PATCH] clk: rockchip: convert rk3036 pll type to use internal lock status

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Message-ID: <3308363.gZKxoYc2QA@phil>
Date:   Tue, 28 Jan 2020 11:26:37 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        mturquette@...libre.com, christoph.muellner@...obroma-systems.com,
        zhangqing@...k-chips.com
Subject: Re: [PATCH] clk: rockchip: convert rk3036 pll type to use internal lock status

Am Dienstag, 14. Januar 2020, 06:05:18 CET schrieb Stephen Boyd:
> Quoting Heiko Stuebner (2020-01-13 07:26:56)
> > diff --git a/drivers/clk/rockchip/clk-pll.c b/drivers/clk/rockchip/clk-pll.c
> > index 198417d56300..37378ded0993 100644
> > --- a/drivers/clk/rockchip/clk-pll.c
> > +++ b/drivers/clk/rockchip/clk-pll.c
> > @@ -118,12 +118,30 @@ static int rockchip_pll_wait_lock(struct rockchip_clk_pll *pll)
> >  #define RK3036_PLLCON1_REFDIV_SHIFT            0
> >  #define RK3036_PLLCON1_POSTDIV2_MASK           0x7
> >  #define RK3036_PLLCON1_POSTDIV2_SHIFT          6
> > +#define RK3036_PLLCON1_LOCK_STATUS             BIT(10)
> >  #define RK3036_PLLCON1_DSMPD_MASK              0x1
> >  #define RK3036_PLLCON1_DSMPD_SHIFT             12
> > +#define RK3036_PLLCON1_PWRDOWN                 BIT(13)
> >  #define RK3036_PLLCON2_FRAC_MASK               0xffffff
> >  #define RK3036_PLLCON2_FRAC_SHIFT              0
> >  
> > -#define RK3036_PLLCON1_PWRDOWN                 (1 << 13)
> > +static int rockchip_rk3036_pll_wait_lock(struct rockchip_clk_pll *pll)
> > +{
> > +       u32 pllcon;
> > +       int delay = 24000000;
> > +
> > +       /* poll check the lock status in rk3399 xPLLCON2 */
> > +       while (delay > 0) {
> > +               pllcon = readl_relaxed(pll->reg_base + RK3036_PLLCON(1));
> > +               if (pllcon & RK3036_PLLCON1_LOCK_STATUS)
> > +                       return 0;
> > +
> > +               delay--;
> 
> There isn't any udelay here. So the timeout is just as fast as the CPU
> can churn through this? Why not use an actual time? Or use the
> readl_poll_timeout() APIs?

Done in 
http://lore.kernel.org/r/20200128100204.1318450-3-heiko@sntech.de

and to keep things similar, I did a conversion to iopoll helpers for the
other variants too.

Heiko