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From: Sowjanya Komatineni <skomatineni@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.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 08/21] clk: tegra: periph: Add restore_context support
Date: Fri, 9 Aug 2019 09:55:59 -0700
Message-ID: <1ef367a5-2f2f-dc66-1e26-9038af235e36@nvidia.com> (raw)
In-Reply-To: <0f8259d8-08f2-671c-331c-fe2d83518be0@gmail.com>


On 8/9/19 5:20 AM, Dmitry Osipenko wrote:
> 09.08.2019 14:55, Dmitry Osipenko пишет:
>> 09.08.2019 2:46, Sowjanya Komatineni пишет:
>>> This patch implements restore_context support for clk-periph and
>>> clk-sdmmc-mux clock operations to restore clock parent and rates
>>> on system resume.
>>>
>>> During system suspend, core power goes off and looses the context
>>> of the Tegra clock controller registers.
>>>
>>> So on system resume, clocks parent and rate are restored back to
>>> the context before suspend based on cached data.
>>>
>>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>>> ---
>>>   drivers/clk/tegra/clk-periph.c    | 18 ++++++++++++++++++
>>>   drivers/clk/tegra/clk-sdmmc-mux.c | 12 ++++++++++++
>>>   2 files changed, 30 insertions(+)
>>>
>>> diff --git a/drivers/clk/tegra/clk-periph.c b/drivers/clk/tegra/clk-periph.c
>>> index 58437da25156..c9d28cbadccc 100644
>>> --- a/drivers/clk/tegra/clk-periph.c
>>> +++ b/drivers/clk/tegra/clk-periph.c
>>> @@ -3,6 +3,7 @@
>>>    * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
>>>    */
>>>   
>>> +#include <linux/clk.h>
>>>   #include <linux/clk-provider.h>
>>>   #include <linux/export.h>
>>>   #include <linux/slab.h>
>>> @@ -99,6 +100,20 @@ static void clk_periph_disable(struct clk_hw *hw)
>>>   	gate_ops->disable(gate_hw);
>>>   }
>>>   
>>> +static void clk_periph_restore_context(struct clk_hw *hw)
>>> +{
>>> +	struct tegra_clk_periph *periph = to_clk_periph(hw);
>>> +	const struct clk_ops *div_ops = periph->div_ops;
>>> +	struct clk_hw *div_hw = &periph->divider.hw;
>>> +	struct clk_hw *parent = clk_hw_get_parent(hw);
>>> +	int parent_id = clk_hw_get_parent_index(hw, parent);
>>> +
>>> +	if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
>>> +		div_ops->restore_context(div_hw);
>>> +
>>> +	clk_periph_set_parent(hw, parent_id);
>>> +}
>>> +
>>>   const struct clk_ops tegra_clk_periph_ops = {
>>>   	.get_parent = clk_periph_get_parent,
>>>   	.set_parent = clk_periph_set_parent,
>>> @@ -108,6 +123,7 @@ const struct clk_ops tegra_clk_periph_ops = {
>>>   	.is_enabled = clk_periph_is_enabled,
>>>   	.enable = clk_periph_enable,
>>>   	.disable = clk_periph_disable,
>>> +	.restore_context = clk_periph_restore_context,
>>>   };
>>>   
>>>   static const struct clk_ops tegra_clk_periph_nodiv_ops = {
>>> @@ -116,6 +132,7 @@ static const struct clk_ops tegra_clk_periph_nodiv_ops = {
>>>   	.is_enabled = clk_periph_is_enabled,
>>>   	.enable = clk_periph_enable,
>>>   	.disable = clk_periph_disable,
>>> +	.restore_context = clk_periph_restore_context,
>>>   };
>>>   
>>>   static const struct clk_ops tegra_clk_periph_no_gate_ops = {
>>> @@ -124,6 +141,7 @@ static const struct clk_ops tegra_clk_periph_no_gate_ops = {
>>>   	.recalc_rate = clk_periph_recalc_rate,
>>>   	.round_rate = clk_periph_round_rate,
>>>   	.set_rate = clk_periph_set_rate,
>>> +	.restore_context = clk_periph_restore_context,
>>>   };
>>>   
>>>   static struct clk *_tegra_clk_register_periph(const char *name,
>>> diff --git a/drivers/clk/tegra/clk-sdmmc-mux.c b/drivers/clk/tegra/clk-sdmmc-mux.c
>>> index a5cd3e31dbae..8db48966b100 100644
>>> --- a/drivers/clk/tegra/clk-sdmmc-mux.c
>>> +++ b/drivers/clk/tegra/clk-sdmmc-mux.c
>>> @@ -194,6 +194,17 @@ static void clk_sdmmc_mux_disable(struct clk_hw *hw)
>>>   	gate_ops->disable(gate_hw);
>>>   }
>>>   
>>> +static void clk_sdmmc_mux_restore_context(struct clk_hw *hw)
>>> +{
>>> +	struct clk_hw *parent = clk_hw_get_parent(hw);
>>> +	unsigned long parent_rate = clk_hw_get_rate(parent);
>>> +	unsigned long rate = clk_hw_get_rate(hw);
>>> +	int parent_id = clk_hw_get_parent_index(hw, parent);
>>> +
>>> +	clk_sdmmc_mux_set_parent(hw, parent_id);
>>> +	clk_sdmmc_mux_set_rate(hw, rate, parent_rate);
>> For the periph clocks you're restoring rate at first and then the
>> parent, while here it's the other way around. I'm wondering if there is
>> any difference in practice and thus whether rate's divider need to be
>> set to a some safe value before switching to a new parent that has a
>> higher clock rate than the old parent.
> Although, I guess that all peripheral clocks should be disabled at this
> point of resume. Correct?

by the time restore happens, peripheral clocks are enabled but held in 
reset state.

For non-boot clocks, doing divider programming before parent source is 
preferred.

For sdmmc clock, programming parent before divisor is allowed.

Also, clk_sdmmc_mux_set_rate gets parent MUX selection thru register 
read so restoring parent prior to this will have right divisor based on 
rate and parent.

>>> +}
>>> +
>>>   static const struct clk_ops tegra_clk_sdmmc_mux_ops = {
>>>   	.get_parent = clk_sdmmc_mux_get_parent,
>>>   	.set_parent = clk_sdmmc_mux_set_parent,
>>> @@ -203,6 +214,7 @@ static const struct clk_ops tegra_clk_sdmmc_mux_ops = {
>>>   	.is_enabled = clk_sdmmc_mux_is_enabled,
>>>   	.enable = clk_sdmmc_mux_enable,
>>>   	.disable = clk_sdmmc_mux_disable,
>>> +	.restore_context = clk_sdmmc_mux_restore_context,
>>>   };
>>>   
>>>   struct clk *tegra_clk_register_sdmmc_mux_div(const char *name,
>>>

  reply index

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 [this message]
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
     [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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