From: Dmitry Osipenko <digetx@gmail.com>
To: Sowjanya Komatineni <skomatineni@nvidia.com>,
thierry.reding@gmail.com, jonathanh@nvidia.com,
tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com,
linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com
Cc: pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org,
linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com,
linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org,
devicetree@vger.kernel.org, rjw@rjwysocki.net,
viresh.kumar@linaro.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v8 14/21] clk: tegra210: Add suspend and resume support
Date: Fri, 9 Aug 2019 21:18:15 +0300 [thread overview]
Message-ID: <aa823801-00c7-df88-0f63-45338bffa854@gmail.com> (raw)
In-Reply-To: <7d101ec9-c559-8b40-1764-6bf67a9c7a7a@nvidia.com>
09.08.2019 19:19, Sowjanya Komatineni пишет:
>
> On 8/9/19 6:56 AM, Dmitry Osipenko wrote:
>> 09.08.2019 2:46, Sowjanya Komatineni пишет:
>>> This patch adds support for clk: tegra210: suspend-resume.
>>>
>>> All the CAR controller settings are lost on suspend when core
>>> power goes off.
>>>
>>> This patch has implementation for saving and restoring all PLLs
>>> and clocks context during system suspend and resume to have the
>>> clocks back to same state for normal operation.
>>>
>>> Clock driver suspend and resume are registered as syscore_ops as clocks
>>> restore need to happen before the other drivers resume to have all their
>>> clocks back to the same state as before suspend.
>>>
>>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>>> ---
>>> drivers/clk/tegra/clk-tegra210.c | 103 +++++++++++++++++++++++++++++++++++++--
>>> drivers/clk/tegra/clk.c | 64 ++++++++++++++++++++++++
>>> drivers/clk/tegra/clk.h | 3 ++
>>> 3 files changed, 166 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c
>>> index 998bf60b219a..8dd6f4f4debb 100644
>>> --- a/drivers/clk/tegra/clk-tegra210.c
>>> +++ b/drivers/clk/tegra/clk-tegra210.c
>>> @@ -9,13 +9,13 @@
>>> #include <linux/clkdev.h>
>>> #include <linux/of.h>
>>> #include <linux/of_address.h>
>>> +#include <linux/syscore_ops.h>
>>> #include <linux/delay.h>
>>> #include <linux/export.h>
>>> #include <linux/mutex.h>
>>> #include <linux/clk/tegra.h>
>>> #include <dt-bindings/clock/tegra210-car.h>
>>> #include <dt-bindings/reset/tegra210-car.h>
>>> -#include <linux/iopoll.h>
>>> #include <linux/sizes.h>
>>> #include <soc/tegra/pmc.h>
>>> @@ -220,11 +220,15 @@
>>> #define CLK_M_DIVISOR_SHIFT 2
>>> #define CLK_M_DIVISOR_MASK 0x3
>>> +#define CLK_MASK_ARM 0x44
>>> +#define MISC_CLK_ENB 0x48
>>> +
>>> #define RST_DFLL_DVCO 0x2f4
>>> #define DVFS_DFLL_RESET_SHIFT 0
>>> #define CLK_RST_CONTROLLER_RST_DEV_Y_SET 0x2a8
>>> #define CLK_RST_CONTROLLER_RST_DEV_Y_CLR 0x2ac
>>> +#define CPU_SOFTRST_CTRL 0x380
>>> #define LVL2_CLK_GATE_OVRA 0xf8
>>> #define LVL2_CLK_GATE_OVRC 0x3a0
>>> @@ -2825,6 +2829,7 @@ static int tegra210_enable_pllu(void)
>>> struct tegra_clk_pll_freq_table *fentry;
>>> struct tegra_clk_pll pllu;
>>> u32 reg;
>>> + int ret;
>>> for (fentry = pll_u_freq_table; fentry->input_rate; fentry++) {
>>> if (fentry->input_rate == pll_ref_freq)
>>> @@ -2853,9 +2858,14 @@ static int tegra210_enable_pllu(void)
>>> reg |= PLL_ENABLE;
>>> writel(reg, clk_base + PLLU_BASE);
>>> - readl_relaxed_poll_timeout_atomic(clk_base + PLLU_BASE, reg,
>>> - reg & PLL_BASE_LOCK, 2, 1000);
>>> - if (!(reg & PLL_BASE_LOCK)) {
>>> + /*
>>> + * During clocks resume, same PLLU init and enable sequence get
>>> + * executed. So, readx_poll_timeout_atomic can't be used here as it
>>> + * uses ktime_get() and timekeeping resume doesn't happen by that
>>> + * time. So, using tegra210_wait_for_mask for PLL LOCK.
>>> + */
>>> + ret = tegra210_wait_for_mask(&pllu, PLLU_BASE, PLL_BASE_LOCK);
>>> + if (ret) {
>>> pr_err("Timed out waiting for PLL_U to lock\n");
>>> return -ETIMEDOUT;
>>> }
>>> @@ -3288,6 +3298,84 @@ static void tegra210_disable_cpu_clock(u32 cpu)
>>> }
>>> #ifdef CONFIG_PM_SLEEP
>>> +/*
>>> + * This array lists mask values for each peripheral clk bank
>>> + * to mask out reserved bits during the clocks state restore
>>> + * on SC7 resume to prevent accidental writes to these reserved
>>> + * bits.
>>> + */
>>> +static u32 periph_clk_rsvd_mask[TEGRA210_CAR_BANK_COUNT] = {
>> Should be more natural to have a "valid_mask" instead of "rsvd_mask".
>>
>> What's actually wrong with touching of the reserved bits? They must be NO-OP.. or the
>> reserved bits are actually some kind of "secret" bits? If those bits have some use-case
>> outside of Silicon HW (like FPGA simulation), then this doesn't matter for upstream and you
>> have to keep the workaround locally in the downstream kernel or whatever.
>
> Will rename as valid_mask.
>
> some bits in these registers are undefined and is not good to write to these bits as they
> can cause pslverr.
Okay, it should be explained in the comment.
Is it possible to disable trapping of changing the undefined bits?
>>
>>> + 0x23282006,
>>> + 0x782e0c18,
>>> + 0x0c012c05,
>>> + 0x003e7304,
>>> + 0x86c04800,
>>> + 0xc0199000,
>>> + 0x03e03800,
>>> +};
>>> +
>>> +#define car_readl(_base, _off) readl_relaxed(clk_base + (_base) + ((_off) * 4))
>>> +#define car_writel(_val, _base, _off) \
>>> + writel_relaxed(_val, clk_base + (_base) + ((_off) * 4))
>>> +
>>> +static u32 spare_reg_ctx, misc_clk_enb_ctx, clk_msk_arm_ctx;
>>> +static u32 cpu_softrst_ctx[3];
>>> +
>>> +static int tegra210_clk_suspend(void)
>>> +{
>>> + unsigned int i;
>>> +
>>> + clk_save_context();
>>> +
>>> + /*
>>> + * Save the bootloader configured clock registers SPARE_REG0,
>>> + * MISC_CLK_ENB, CLK_MASK_ARM, CPU_SOFTRST_CTRL.
>>> + */
>>> + spare_reg_ctx = readl_relaxed(clk_base + SPARE_REG0);
>>> + misc_clk_enb_ctx = readl_relaxed(clk_base + MISC_CLK_ENB);
>>> + clk_msk_arm_ctx = readl_relaxed(clk_base + CLK_MASK_ARM);
>>> +
>>> + for (i = 0; i < ARRAY_SIZE(cpu_softrst_ctx); i++)
>>> + cpu_softrst_ctx[i] = car_readl(CPU_SOFTRST_CTRL, i);
>>> +
>>> + tegra_clk_periph_suspend();
>>> + return 0;
>>> +}
>>> +
>>> +static void tegra210_clk_resume(void)
>>> +{
>>> + unsigned int i;
>>> +
>>> + tegra_clk_osc_resume(clk_base);
>>> +
>>> + /*
>>> + * Restore the bootloader configured clock registers SPARE_REG0,
>>> + * MISC_CLK_ENB, CLK_MASK_ARM, CPU_SOFTRST_CTRL from saved context.
>>> + */
>>> + writel_relaxed(spare_reg_ctx, clk_base + SPARE_REG0);
>>> + writel_relaxed(misc_clk_enb_ctx, clk_base + MISC_CLK_ENB);
>>> + writel_relaxed(clk_msk_arm_ctx, clk_base + CLK_MASK_ARM);
>>> +
>>> + for (i = 0; i < ARRAY_SIZE(cpu_softrst_ctx); i++)
>>> + car_writel(cpu_softrst_ctx[i], CPU_SOFTRST_CTRL, i);
>>> +
>>> + fence_udelay(5, clk_base);
>>> +
>>> + /* enable all the clocks before changing the clock sources */
>>> + tegra_clk_periph_force_on(periph_clk_rsvd_mask);
>> Why clocks need to be enabled before changing the sources?
>
> To prevent glitchless frequency switch, Tegra clock programming recommended sequence is to
> change MUX control or divisor or both with the clocks running.
This should be explained in the comment.
> Actual state of clocks before suspend are restored later after all PLL's and peripheral
> clocks are restored.
>
>>
>>> + /* wait for all writes to happen to have all the clocks enabled */
>>> + wmb();
>> fence_udelay() has exactly the same barrier at the very beginning of readl(), no need to
>> duplicate it here.
Actually, readl does the rmb() and it should be a more correct variant of fencing because it
actually ensures that the write reached hardware. I suppose that something like fence_udelay
should be used for the pinctrl as well.
>>> + fence_udelay(2, clk_base);
>>> +
>>> + /* restore PLLs and all peripheral clock rates */
>>> + tegra210_init_pllu();
>> Why USB PLL need to be restored at first?
> USB PLL restore is independent to all other clocks restore. So this can be done either
> before clk_restore_context or even after.
Then why not to implement restore_context for PLLU?
>>> + clk_restore_context();
>>> +
>>> + /* restore all peripheral clocks enable and reset state */
>>> + tegra_clk_periph_resume();
>>> +}
>> [snip]
next prev parent reply other threads:[~2019-08-09 18:18 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 23:46 [PATCH v8 00/21] SC7 entry and exit support for Tegra210 Sowjanya Komatineni
2019-08-08 23:46 ` [PATCH v8 01/21] pinctrl: tegra: Fix write barrier placement in pmx_writel Sowjanya Komatineni
2019-08-09 11:38 ` Dmitry Osipenko
2019-08-12 9:20 ` Thierry Reding
2019-08-14 8:32 ` Linus Walleij
2019-08-08 23:46 ` [PATCH v8 02/21] pinctrl: tegra: Add write barrier after all pinctrl register writes Sowjanya Komatineni
2019-08-09 11:39 ` Dmitry Osipenko
2019-08-12 9:20 ` Thierry Reding
2019-08-14 8:33 ` Linus Walleij
2019-08-08 23:46 ` [PATCH v8 03/21] clk: tegra: divider: Save and restore divider rate Sowjanya Komatineni
2019-08-12 9:21 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 04/21] clk: tegra: pllout: Save and restore pllout context Sowjanya Komatineni
2019-08-11 18:04 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 05/21] clk: tegra: pll: Save and restore pll context Sowjanya Komatineni
2019-08-09 11:33 ` Dmitry Osipenko
2019-08-09 17:39 ` Sowjanya Komatineni
2019-08-09 17:50 ` Dmitry Osipenko
2019-08-09 18:50 ` Sowjanya Komatineni
2019-08-11 17:24 ` Dmitry Osipenko
2019-08-09 12:46 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 06/21] clk: tegra: Support for OSC context save and restore Sowjanya Komatineni
2019-08-08 23:46 ` [PATCH v8 07/21] clk: Add API to get index of the clock parent Sowjanya Komatineni
2019-08-09 11:49 ` Dmitry Osipenko
2019-08-12 9:47 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 08/21] clk: tegra: periph: Add restore_context support Sowjanya Komatineni
2019-08-09 11:55 ` Dmitry Osipenko
2019-08-09 12:20 ` Dmitry Osipenko
2019-08-09 16:55 ` Sowjanya Komatineni
2019-08-12 9:50 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 09/21] clk: tegra: clk-super: Fix to enable PLLP branches to CPU Sowjanya Komatineni
2019-08-09 12:11 ` Dmitry Osipenko
2019-08-12 9:53 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 10/21] clk: tegra: clk-super: Add restore-context support Sowjanya Komatineni
2019-08-09 12:17 ` Dmitry Osipenko
2019-08-09 17:08 ` Sowjanya Komatineni
2019-08-11 17:29 ` Dmitry Osipenko
2019-08-12 9:55 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 11/21] clk: tegra: clk-dfll: Add suspend and resume support Sowjanya Komatineni
2019-08-09 12:23 ` Dmitry Osipenko
2019-08-09 16:39 ` Sowjanya Komatineni
2019-08-09 18:00 ` Dmitry Osipenko
2019-08-09 18:33 ` Sowjanya Komatineni
2019-08-09 18:52 ` Dmitry Osipenko
2019-08-12 10:01 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 12/21] cpufreq: tegra124: " Sowjanya Komatineni
2019-08-12 10:07 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 13/21] clk: tegra210: Use fence_udelay during PLLU init Sowjanya Komatineni
2019-08-11 18:02 ` Dmitry Osipenko
2019-08-11 19:16 ` Sowjanya Komatineni
2019-08-08 23:46 ` [PATCH v8 14/21] clk: tegra210: Add suspend and resume support Sowjanya Komatineni
2019-08-09 13:56 ` Dmitry Osipenko
2019-08-09 16:19 ` Sowjanya Komatineni
2019-08-09 18:18 ` Dmitry Osipenko [this message]
[not found] ` <cbe94f84-a17b-7e1a-811d-89db571784e1@nvidia.com>
2019-08-11 17:39 ` Dmitry Osipenko
2019-08-11 19:15 ` Sowjanya Komatineni
2019-08-12 16:25 ` Dmitry Osipenko
2019-08-12 17:28 ` Sowjanya Komatineni
2019-08-12 18:19 ` Dmitry Osipenko
2019-08-12 19:03 ` Sowjanya Komatineni
2019-08-12 20:28 ` Dmitry Osipenko
2019-08-12 10:17 ` Thierry Reding
2019-08-08 23:46 ` [PATCH v8 15/21] soc/tegra: pmc: Allow to support more tegras wake Sowjanya Komatineni
2019-08-11 17:52 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 16/21] soc/tegra: pmc: Add pmc wake support for tegra210 Sowjanya Komatineni
2019-08-09 13:28 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 17/21] arm64: tegra: Enable wake from deep sleep on RTC alarm Sowjanya Komatineni
2019-08-08 23:46 ` [PATCH v8 18/21] soc/tegra: pmc: Configure core power request polarity Sowjanya Komatineni
2019-08-09 13:13 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 19/21] soc/tegra: pmc: Configure deep sleep control settings Sowjanya Komatineni
2019-08-09 13:23 ` Dmitry Osipenko
2019-08-09 16:23 ` Sowjanya Komatineni
2019-08-09 17:24 ` Sowjanya Komatineni
2019-08-09 18:22 ` Dmitry Osipenko
2019-08-08 23:46 ` [PATCH v8 20/21] arm64: dts: tegra210-p2180: Jetson TX1 SC7 timings Sowjanya Komatineni
2019-08-08 23:47 ` [PATCH v8 21/21] arm64: dts: tegra210-p3450: Jetson Nano " Sowjanya Komatineni
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