Re: [PATCH v5] clk: tegra: Initialize UTMIPLL when enabling PLLU

[Rhyland Klein <rklein@nvidia.com>]

On 6/30/2016 11:37 AM, Thierry Reding wrote:
> * PGP Signed by an unknown key
> 
> On Thu, Jun 30, 2016 at 11:32:14AM -0400, Rhyland Klein wrote:
>> On 6/17/2016 11:23 AM, Thierry Reding wrote:
>>>> Old 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@chromium.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@chromium.org>
>>>>>
>>>>> [rklein: Merged in some later fixes for potential deadlocks]
>>>>>
>>>>> Signed-off-by: Rhyland Klein <rklein@nvidia.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?
>>>
>>
>> It looks like we should be able to use a short udelay of 1-2us. I
>> believe the original code had udelay(1) and I know Jon and I tested
>> udelay(2) and it was ok.
> 
> What original code? The downstream driver? If so I'd be leaning towards
> simply adopting that. Everything else in this functions seems to want to
> wait for 1 us, seems natural for this to do as well.

Sorry I wasn't clear. The code in the clk-tegraXX specific drivers was
using udelay(1) as you pointed out, thats what I meant.

> 
>> Do you want me to send another patch rev with just the udelay change or
>> are you going to just modify it locally yourself?
> 
> No need to resend, I'll cherry-pick the patch from next-20160617 and
> make this into udelay(1).

Thanks!

-rhyland

-- 
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