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Message-ID: <20160617152336.GA27475@ulmo.ba.sec>
Date: Fri, 17 Jun 2016 17:23:36 +0200
From: Thierry Reding <thierry.reding@...il.com>
To: Jon Hunter <jonathanh@...dia.com>
Cc: Rhyland Klein <rklein@...dia.com>,
Peter De Schrijver <pdeschrijver@...dia.com>,
Mike Turquette <mturquette@...libre.com>,
Stephen Warren <swarren@...dotorg.org>,
Stephen Boyd <sboyd@...eaurora.org>,
Alexandre Courbot <gnurou@...il.com>,
linux-clk@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org,
Andrew Bresticker <abrestic@...omium.org>
Subject: Re: [PATCH v5] clk: tegra: Initialize UTMIPLL when enabling PLLU
On Fri, Jun 17, 2016 at 02:49:41PM +0100, Jon Hunter wrote:
> Hi Thierry,
>
> On 26/05/16 17:41, Rhyland Klein wrote:
> > From: Andrew Bresticker <abrestic@...omium.org>
> >
> > Move the UTMIPLL initialization code form clk-tegra<chip>.c files into
> > clk-pll.c. UTMIPLL was being configured and set in HW control right
> > after registration. However, when the clock init_table is processed and
> > child clks of PLLU are enabled, it will call in and enable PLLU as
> > well, and initiate SW enabling sequence even though PLLU is already in
> > HW control. This leads to getting UTMIPLL stuck with a SEQ_BUSY status.
> >
> > Doing the initialization once during pllu_enable means we configure it
> > properly into HW control.
> >
> > A side effect of the commonization/localization of the UTMIPLL init
> > code, is that it corrects some errors that were present for earlier
> > generations. For instance, in clk-tegra124.c, it used to have:
> >
> > define UTMIP_PLL_CFG1_ENABLE_DLY_COUNT(x) (((x) & 0x1f) << 6)
> >
> > when the correct shift to use is present in the new version:
> >
> > define UTMIP_PLL_CFG1_ENABLE_DLY_COUNT(x) (((x) & 0x1f) << 27)
> >
> > which matches the Tegra124 TRM register definition.
> >
> > Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
> >
> > [rklein: Merged in some later fixes for potential deadlocks]
> >
> > Signed-off-by: Rhyland Klein <rklein@...dia.com>
> > ---
> > v5:
> > - Initialized flags to 0 to avoid harmless spinlock warnings
> >
> > v4:
> > - Re-added examples in patch description
> >
> > v3:
> > - Flushed out description to describe this patch.
> >
> > drivers/clk/tegra/clk-pll.c | 484 +++++++++++++++++++++++++++++++++++++++
> > drivers/clk/tegra/clk-tegra114.c | 155 +------------
> > drivers/clk/tegra/clk-tegra124.c | 156 +------------
> > drivers/clk/tegra/clk-tegra210.c | 182 +--------------
> > drivers/clk/tegra/clk-tegra30.c | 113 +--------
> > drivers/clk/tegra/clk.h | 17 ++
> > 6 files changed, 510 insertions(+), 597 deletions(-)
> >
> > diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
> > index 4e194ecc8d5e..31e20110fae4 100644
> > --- a/drivers/clk/tegra/clk-pll.c
> > +++ b/drivers/clk/tegra/clk-pll.c
>
> ...
>
> > +static int clk_pllu_tegra210_enable(struct clk_hw *hw)
> > +{
> > + struct tegra_clk_pll *pll = to_clk_pll(hw);
> > + struct clk_hw *pll_ref = clk_hw_get_parent(hw);
> > + struct clk_hw *osc = clk_hw_get_parent(pll_ref);
> > + unsigned long flags = 0, input_rate;
> > + unsigned int i;
> > + int ret = 0;
> > + u32 val;
> > +
> > + if (!osc) {
> > + pr_err("%s: failed to get OSC clock\n", __func__);
> > + return -EINVAL;
> > + }
> > + input_rate = clk_hw_get_rate(osc);
> > +
> > + if (pll->lock)
> > + spin_lock_irqsave(pll->lock, flags);
> > +
> > + _clk_pll_enable(hw);
> > + ret = clk_pll_wait_for_lock(pll);
> > + if (ret < 0)
> > + goto out;
> > +
> > + for (i = 0; i < ARRAY_SIZE(utmi_parameters); i++) {
> > + if (input_rate == utmi_parameters[i].osc_frequency)
> > + break;
> > + }
> > +
> > + if (i == ARRAY_SIZE(utmi_parameters)) {
> > + pr_err("%s: Unexpected input rate %lu\n", __func__, input_rate);
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > +
> > + val = pll_readl_base(pll);
> > + val &= ~PLLU_BASE_OVERRIDE;
> > + pll_writel_base(val, pll);
> > +
> > + /* Put PLLU under HW control */
> > + val = readl_relaxed(pll->clk_base + PLLU_HW_PWRDN_CFG0);
> > + val |= PLLU_HW_PWRDN_CFG0_IDDQ_PD_INCLUDE |
> > + PLLU_HW_PWRDN_CFG0_USE_SWITCH_DETECT |
> > + PLLU_HW_PWRDN_CFG0_USE_LOCKDET;
> > + val &= ~(PLLU_HW_PWRDN_CFG0_CLK_ENABLE_SWCTL |
> > + PLLU_HW_PWRDN_CFG0_CLK_SWITCH_SWCTL);
> > + writel_relaxed(val, pll->clk_base + PLLU_HW_PWRDN_CFG0);
> > +
> > + val = readl_relaxed(pll->clk_base + XUSB_PLL_CFG0);
> > + val &= ~XUSB_PLL_CFG0_PLLU_LOCK_DLY;
> > + writel_relaxed(val, pll->clk_base + XUSB_PLL_CFG0);
> > + udelay(1);
> > +
> > + val = readl_relaxed(pll->clk_base + PLLU_HW_PWRDN_CFG0);
> > + val |= PLLU_HW_PWRDN_CFG0_SEQ_ENABLE;
> > + writel_relaxed(val, pll->clk_base + PLLU_HW_PWRDN_CFG0);
> > + udelay(1);
> > +
> > + /* Disable PLLU clock branch to UTMIPLL since it uses OSC */
> > + val = pll_readl_base(pll);
> > + val &= ~PLLU_BASE_CLKENABLE_USB;
> > + pll_writel_base(val, pll);
> > +
> > + val = readl_relaxed(pll->clk_base + UTMIPLL_HW_PWRDN_CFG0);
> > + if (val & UTMIPLL_HW_PWRDN_CFG0_SEQ_ENABLE) {
> > + pr_debug("UTMIPLL already enabled\n");
> > + goto out;
> > + }
> > + val &= ~UTMIPLL_HW_PWRDN_CFG0_IDDQ_OVERRIDE;
> > + writel_relaxed(val, pll->clk_base + UTMIPLL_HW_PWRDN_CFG0);
> > +
> > + /* Program UTMIP PLL stable and active counts */
> > + val = readl_relaxed(pll->clk_base + UTMIP_PLL_CFG2);
> > + val &= ~UTMIP_PLL_CFG2_STABLE_COUNT(~0);
> > + val |= UTMIP_PLL_CFG2_STABLE_COUNT(utmi_parameters[i].stable_count);
> > + val &= ~UTMIP_PLL_CFG2_ACTIVE_DLY_COUNT(~0);
> > + val |= UTMIP_PLL_CFG2_ACTIVE_DLY_COUNT(
> > + utmi_parameters[i].active_delay_count);
> > + val |= UTMIP_PLL_CFG2_PHY_XTAL_CLOCKEN;
> > + writel_relaxed(val, pll->clk_base + UTMIP_PLL_CFG2);
> > +
> > + /* Program UTMIP PLL delay and oscillator frequency counts */
> > + val = readl_relaxed(pll->clk_base + UTMIP_PLL_CFG1);
> > + val &= ~UTMIP_PLL_CFG1_ENABLE_DLY_COUNT(~0);
> > + val |= UTMIP_PLL_CFG1_ENABLE_DLY_COUNT(
> > + utmi_parameters[i].enable_delay_count);
> > + val &= ~UTMIP_PLL_CFG1_XTAL_FREQ_COUNT(~0);
> > + val |= UTMIP_PLL_CFG1_XTAL_FREQ_COUNT(
> > + utmi_parameters[i].xtal_freq_count);
> > + writel_relaxed(val, pll->clk_base + UTMIP_PLL_CFG1);
> > +
> > + /* Remove power downs from UTMIP PLL control bits */
> > + val = readl_relaxed(pll->clk_base + UTMIP_PLL_CFG1);
> > + val &= ~UTMIP_PLL_CFG1_FORCE_PLL_ENABLE_POWERDOWN;
> > + val |= UTMIP_PLL_CFG1_FORCE_PLL_ENABLE_POWERUP;
> > + writel_relaxed(val, pll->clk_base + UTMIP_PLL_CFG1);
> > + udelay(100);
>
> In next-20160617 I see that this udelay is now a usleep_range(100, 200)
> and this is causing the following splat when the clock is enabled. I
> don't think that we can use usleep here ...
Okay, I'll back out the patch. I'd really prefer to avoid busy-looping
for 100 microseconds here, so can we please find another way to do this?
Thierry
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