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Message-ID: <5f8aa644-27cb-457f-c7cc-e84014054272@nvidia.com>
Date: Mon, 20 Jun 2016 13:24:07 -0400
From: Rhyland Klein <rklein@...dia.com>
To: Thierry Reding <thierry.reding@...il.com>,
Jon Hunter <jonathanh@...dia.com>
CC: 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 6/17/2016 11:23 AM, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> 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?
>
I discussed this with some people downstream, and they said we should
never need to wait 100 microseconds, and should never need more then
1-2us for delays to take effect.
Therefore I would think changing this to a udelay(2) should be alright.
I simply enabled the clock, and it seemed to be fine. I'll send a new
version with that change if you want.
-rhyland
--
nvpublic
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