Message-ID: <274e67b1-16b8-2475-d026-68bd89b090ec@nvidia.com>
Date:   Sat, 3 Aug 2019 10:01:56 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <tglx@...utronix.de>,
        <jason@...edaemon.net>, <marc.zyngier@....com>,
        <linus.walleij@...aro.org>, <stefan@...er.ch>,
        <mark.rutland@....com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>, <jckuo@...dia.com>,
        <josephl@...dia.com>, <talho@...dia.com>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <mperttunen@...dia.com>, <spatra@...dia.com>, <robh+dt@...nel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v7 07/20] clk: tegra: clk-periph: Add save and restore
 support


On 8/3/19 3:33 AM, Dmitry Osipenko wrote:
> 03.08.2019 2:51, Sowjanya Komatineni пишет:
>> On 8/2/19 2:15 PM, Dmitry Osipenko wrote:
>>> 02.08.2019 23:32, Sowjanya Komatineni пишет:
>>>> On 8/2/19 1:17 PM, Dmitry Osipenko wrote:
>>>>> 02.08.2019 23:13, Dmitry Osipenko пишет:
>>>>>> 02.08.2019 21:33, Sowjanya Komatineni пишет:
>>>>>>> On 8/2/19 5:38 AM, Dmitry Osipenko wrote:
>>>>>>>> 02.08.2019 2:49, Sowjanya Komatineni пишет:
>>>>>>>>> On 8/1/19 4:19 PM, Sowjanya Komatineni wrote:
>>>>>>>>>> On 8/1/19 2:30 PM, Sowjanya Komatineni wrote:
>>>>>>>>>>> On 8/1/19 1:54 PM, Dmitry Osipenko wrote:
>>>>>>>>>>>> 01.08.2019 23:31, Sowjanya Komatineni пишет:
>>>>>>>>>>>>> On 8/1/19 1:17 PM, Dmitry Osipenko wrote:
>>>>>>>>>>>>>> 01.08.2019 22:42, Sowjanya Komatineni пишет:
>>>>>>>>>>>>>>> On 8/1/19 12:00 PM, Dmitry Osipenko wrote:
>>>>>>>>>>>>>>>> 01.08.2019 20:58, Sowjanya Komatineni пишет:
>>>>>>>>>>>>>>>>> On 7/31/19 4:09 PM, Sowjanya Komatineni wrote:
>>>>>>>>>>>>>>>>>> On 7/31/19 3:44 AM, Dmitry Osipenko wrote:
>>>>>>>>>>>>>>>>>>> 31.07.2019 12:50, Dmitry Osipenko пишет:
>>>>>>>>>>>>>>>>>>>> 31.07.2019 3:20, Sowjanya Komatineni пишет:
>>>>>>>>>>>>>>>>>>>>> This patch implements save and restore context for
>>>>>>>>>>>>>>>>>>>>> peripheral
>>>>>>>>>>>>>>>>>>>>> fixed
>>>>>>>>>>>>>>>>>>>>> clock ops, peripheral gate clock ops, sdmmc mux clock
>>>>>>>>>>>>>>>>>>>>> ops, and
>>>>>>>>>>>>>>>>>>>>> peripheral clock ops.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> During system suspend, core power goes off and
>>>>>>>>>>>>>>>>>>>>> looses the
>>>>>>>>>>>>>>>>>>>>> settings
>>>>>>>>>>>>>>>>>>>>> of the Tegra CAR controller registers.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> So during suspend entry clock and reset state of
>>>>>>>>>>>>>>>>>>>>> peripherals is
>>>>>>>>>>>>>>>>>>>>> saved
>>>>>>>>>>>>>>>>>>>>> and on resume they are restored to have clocks back to
>>>>>>>>>>>>>>>>>>>>> same
>>>>>>>>>>>>>>>>>>>>> rate and
>>>>>>>>>>>>>>>>>>>>> state as before suspend.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Acked-by: Thierry Reding <treding@...dia.com>
>>>>>>>>>>>>>>>>>>>>> Signed-off-by: Sowjanya Komatineni
>>>>>>>>>>>>>>>>>>>>> <skomatineni@...dia.com>
>>>>>>>>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>>>>>>>>>          drivers/clk/tegra/clk-periph-fixed.c | 33
>>>>>>>>>>>>>>>>>>>>> ++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>>>          drivers/clk/tegra/clk-periph-gate.c  | 34
>>>>>>>>>>>>>>>>>>>>> +++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>>>          drivers/clk/tegra/clk-periph.c       | 37
>>>>>>>>>>>>>>>>>>>>> ++++++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>>>          drivers/clk/tegra/clk-sdmmc-mux.c    | 28
>>>>>>>>>>>>>>>>>>>>> +++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>>>          drivers/clk/tegra/clk.h              | 6 ++++++
>>>>>>>>>>>>>>>>>>>>>          5 files changed, 138 insertions(+)
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> diff --git a/drivers/clk/tegra/clk-periph-fixed.c
>>>>>>>>>>>>>>>>>>>>> b/drivers/clk/tegra/clk-periph-fixed.c
>>>>>>>>>>>>>>>>>>>>> index c088e7a280df..21b24530fa00 100644
>>>>>>>>>>>>>>>>>>>>> --- a/drivers/clk/tegra/clk-periph-fixed.c
>>>>>>>>>>>>>>>>>>>>> +++ b/drivers/clk/tegra/clk-periph-fixed.c
>>>>>>>>>>>>>>>>>>>>> @@ -60,11 +60,44 @@
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_recalc_rate(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw *hw,
>>>>>>>>>>>>>>>>>>>>>              return (unsigned long)rate;
>>>>>>>>>>>>>>>>>>>>>          }
>>>>>>>>>>>>>>>>>>>>>          +static int
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_save_context(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph_fixed *fixed =
>>>>>>>>>>>>>>>>>>>>> to_tegra_clk_periph_fixed(hw);
>>>>>>>>>>>>>>>>>>>>> +    u32 mask = 1 << (fixed->num % 32);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    fixed->enb_ctx = readl_relaxed(fixed->base +
>>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_reg) &
>>>>>>>>>>>>>>>>>>>>> +             mask;
>>>>>>>>>>>>>>>>>>>>> +    fixed->rst_ctx = readl_relaxed(fixed->base +
>>>>>>>>>>>>>>>>>>>>> fixed->regs->rst_reg) &
>>>>>>>>>>>>>>>>>>>>> +             mask;
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    return 0;
>>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +static void
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_restore_context(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph_fixed *fixed =
>>>>>>>>>>>>>>>>>>>>> to_tegra_clk_periph_fixed(hw);
>>>>>>>>>>>>>>>>>>>>> +    u32 mask = 1 << (fixed->num % 32);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (fixed->enb_ctx)
>>>>>>>>>>>>>>>>>>>>> +        writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_set_reg);
>>>>>>>>>>>>>>>>>>>>> +    else
>>>>>>>>>>>>>>>>>>>>> +        writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_clr_reg);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    udelay(2);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (!fixed->rst_ctx) {
>>>>>>>>>>>>>>>>>>>>> +        udelay(5); /* reset propogation delay */
>>>>>>>>>>>>>>>>>>>>> +        writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>>> fixed->regs->rst_reg);
>>>>>>>>>>>>>>>>>>>>> +    }
>>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>>          static const struct clk_ops
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_ops
>>>>>>>>>>>>>>>>>>>>> = {
>>>>>>>>>>>>>>>>>>>>>              .is_enabled =
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_is_enabled,
>>>>>>>>>>>>>>>>>>>>>              .enable = tegra_clk_periph_fixed_enable,
>>>>>>>>>>>>>>>>>>>>>              .disable = tegra_clk_periph_fixed_disable,
>>>>>>>>>>>>>>>>>>>>>              .recalc_rate =
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_recalc_rate,
>>>>>>>>>>>>>>>>>>>>> +    .save_context =
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_save_context,
>>>>>>>>>>>>>>>>>>>>> +    .restore_context =
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_restore_context,
>>>>>>>>>>>>>>>>>>>>>          };
>>>>>>>>>>>>>>>>>>>>>            struct clk
>>>>>>>>>>>>>>>>>>>>> *tegra_clk_register_periph_fixed(const
>>>>>>>>>>>>>>>>>>>>> char
>>>>>>>>>>>>>>>>>>>>> *name,
>>>>>>>>>>>>>>>>>>>>> diff --git a/drivers/clk/tegra/clk-periph-gate.c
>>>>>>>>>>>>>>>>>>>>> b/drivers/clk/tegra/clk-periph-gate.c
>>>>>>>>>>>>>>>>>>>>> index 4b31beefc9fc..6ba5b08e0787 100644
>>>>>>>>>>>>>>>>>>>>> --- a/drivers/clk/tegra/clk-periph-gate.c
>>>>>>>>>>>>>>>>>>>>> +++ b/drivers/clk/tegra/clk-periph-gate.c
>>>>>>>>>>>>>>>>>>>>> @@ -25,6 +25,8 @@ static
>>>>>>>>>>>>>>>>>>>>> DEFINE_SPINLOCK(periph_ref_lock);
>>>>>>>>>>>>>>>>>>>>>            #define read_rst(gate) \
>>>>>>>>>>>>>>>>>>>>>              readl_relaxed(gate->clk_base +
>>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_reg))
>>>>>>>>>>>>>>>>>>>>> +#define write_rst_set(val, gate) \
>>>>>>>>>>>>>>>>>>>>> +    writel_relaxed(val, gate->clk_base +
>>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_set_reg))
>>>>>>>>>>>>>>>>>>>>>          #define write_rst_clr(val, gate) \
>>>>>>>>>>>>>>>>>>>>>              writel_relaxed(val, gate->clk_base +
>>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_clr_reg))
>>>>>>>>>>>>>>>>>>>>>          @@ -110,10 +112,42 @@ static void
>>>>>>>>>>>>>>>>>>>>> clk_periph_disable(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw *hw)
>>>>>>>>>>>>>>>>>>>>> spin_unlock_irqrestore(&periph_ref_lock, flags);
>>>>>>>>>>>>>>>>>>>>>          }
>>>>>>>>>>>>>>>>>>>>>          +static int clk_periph_gate_save_context(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph_gate *gate =
>>>>>>>>>>>>>>>>>>>>> to_clk_periph_gate(hw);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    gate->clk_state_ctx = read_enb(gate) &
>>>>>>>>>>>>>>>>>>>>> periph_clk_to_bit(gate);
>>>>>>>>>>>>>>>>>>>>> +    gate->rst_state_ctx = read_rst(gate) &
>>>>>>>>>>>>>>>>>>>>> periph_clk_to_bit(gate);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    return 0;
>>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +static void clk_periph_gate_restore_context(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph_gate *gate =
>>>>>>>>>>>>>>>>>>>>> to_clk_periph_gate(hw);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (gate->clk_state_ctx)
>>>>>>>>>>>>>>>>>>>>> + write_enb_set(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>>> +    else
>>>>>>>>>>>>>>>>>>>>> + write_enb_clr(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    udelay(5);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
>>>>>>>>>>>>>>>>>>>>> +        !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
>>>>>>>>>>>>>>>>>>>>> +        if (gate->rst_state_ctx)
>>>>>>>>>>>>>>>>>>>>> + write_rst_set(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>>> +        else
>>>>>>>>>>>>>>>>>>>>> + write_rst_clr(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>>> +    }
>>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>>          const struct clk_ops
>>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_gate_ops = {
>>>>>>>>>>>>>>>>>>>>>              .is_enabled = clk_periph_is_enabled,
>>>>>>>>>>>>>>>>>>>>>              .enable = clk_periph_enable,
>>>>>>>>>>>>>>>>>>>>>              .disable = clk_periph_disable,
>>>>>>>>>>>>>>>>>>>>> +    .save_context = clk_periph_gate_save_context,
>>>>>>>>>>>>>>>>>>>>> +    .restore_context =
>>>>>>>>>>>>>>>>>>>>> clk_periph_gate_restore_context,
>>>>>>>>>>>>>>>>>>>>>          };
>>>>>>>>>>>>>>>>>>>>>            struct clk
>>>>>>>>>>>>>>>>>>>>> *tegra_clk_register_periph_gate(const
>>>>>>>>>>>>>>>>>>>>> char *name,
>>>>>>>>>>>>>>>>>>>>> diff --git a/drivers/clk/tegra/clk-periph.c
>>>>>>>>>>>>>>>>>>>>> b/drivers/clk/tegra/clk-periph.c
>>>>>>>>>>>>>>>>>>>>> index 58437da25156..06fb62955768 100644
>>>>>>>>>>>>>>>>>>>>> --- a/drivers/clk/tegra/clk-periph.c
>>>>>>>>>>>>>>>>>>>>> +++ b/drivers/clk/tegra/clk-periph.c
>>>>>>>>>>>>>>>>>>>>> @@ -99,6 +99,37 @@ static void
>>>>>>>>>>>>>>>>>>>>> clk_periph_disable(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>>              gate_ops->disable(gate_hw);
>>>>>>>>>>>>>>>>>>>>>          }
>>>>>>>>>>>>>>>>>>>>>          +static int clk_periph_save_context(struct
>>>>>>>>>>>>>>>>>>>>> clk_hw *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph *periph =
>>>>>>>>>>>>>>>>>>>>> to_clk_periph(hw);
>>>>>>>>>>>>>>>>>>>>> +    const struct clk_ops *gate_ops = periph->gate_ops;
>>>>>>>>>>>>>>>>>>>>> +    struct clk_hw *gate_hw = &periph->gate.hw;
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
>>>>>>>>>>>>>>>>>>>>> +        gate_ops->save_context(gate_hw);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    periph->parent_ctx = clk_periph_get_parent(hw);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    return 0;
>>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +static void clk_periph_restore_context(struct clk_hw
>>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>>> +    struct tegra_clk_periph *periph =
>>>>>>>>>>>>>>>>>>>>> to_clk_periph(hw);
>>>>>>>>>>>>>>>>>>>>> +    const struct clk_ops *gate_ops = periph->gate_ops;
>>>>>>>>>>>>>>>>>>>>> +    struct clk_hw *gate_hw = &periph->gate.hw;
>>>>>>>>>>>>>>>>>>>>> +    const struct clk_ops *div_ops = periph->div_ops;
>>>>>>>>>>>>>>>>>>>>> +    struct clk_hw *div_hw = &periph->divider.hw;
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    clk_periph_set_parent(hw, periph->parent_ctx);
>>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>>> +    if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
>>>>>>>>>>>>>>>>>>>>> + div_ops->restore_context(div_hw);
>>>>>>>>>>>>>>>>>>>> Could you please point to where the divider's
>>>>>>>>>>>>>>>>>>>> save_context()
>>>>>>>>>>>>>>>>>>>> happens?
>>>>>>>>>>>>>>>>>>>> Because I can't see it.
>>>>>>>>>>>>>>>>>>> Ah, I now see that there is no need to save the dividers
>>>>>>>>>>>>>>>>>>> context
>>>>>>>>>>>>>>>>>>> because
>>>>>>>>>>>>>>>>>>> clk itself has enough info that is needed for the
>>>>>>>>>>>>>>>>>>> context's
>>>>>>>>>>>>>>>>>>> restoring
>>>>>>>>>>>>>>>>>>> (like I pointed in the review to v6).
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Looks like you could also implement a new
>>>>>>>>>>>>>>>>>>> clk_hw_get_parent_index()
>>>>>>>>>>>>>>>>>>> generic helper to get the index instead of storing it
>>>>>>>>>>>>>>>>>>> manually.
>>>>>>>>>>>>>>>>>> clk_periph_get_parent basically invokes existing
>>>>>>>>>>>>>>>>>> clk_mux_ops
>>>>>>>>>>>>>>>>>> get_parent() which is then saved in tegra_clk_periph.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> All existing drivers are using directly get_parent() from
>>>>>>>>>>>>>>>>>> clk_mux
>>>>>>>>>>>>>>>>>> which actually gets index from the register read.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> To have this more generic w.r.t save/restore context
>>>>>>>>>>>>>>>>>> point of
>>>>>>>>>>>>>>>>>> view,
>>>>>>>>>>>>>>>>>> probably instead of implementing new get_parent_index
>>>>>>>>>>>>>>>>>> helper,
>>>>>>>>>>>>>>>>>> I think
>>>>>>>>>>>>>>>>>> its better to implement save_context and
>>>>>>>>>>>>>>>>>> restore_context to
>>>>>>>>>>>>>>>>>> clk_mux_ops along with creating parent_index field into
>>>>>>>>>>>>>>>>>> clk_mux to
>>>>>>>>>>>>>>>>>> cache index during set_parent.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> So we just need to invoke mux_ops save_context and
>>>>>>>>>>>>>>>>>> restore_context.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I hope its ok to add save/restore context to clk_mux_ops
>>>>>>>>>>>>>>>>> to be
>>>>>>>>>>>>>>>>> more
>>>>>>>>>>>>>>>>> generic w.r.t save/restore context rather than
>>>>>>>>>>>>>>>>> get_parent_index
>>>>>>>>>>>>>>>>> API.
>>>>>>>>>>>>>>>>> Please confirm if you agree.
>>>>>>>>>>>>>>>> Sounds like a good idea. I see that there is a 'restoring'
>>>>>>>>>>>>>>>> helper for
>>>>>>>>>>>>>>>> the generic clk_gate, seems something similar could be done
>>>>>>>>>>>>>>>> for the
>>>>>>>>>>>>>>>> clk_mux. And looks like anyway you'll need to associate the
>>>>>>>>>>>>>>>> parent
>>>>>>>>>>>>>>>> clock
>>>>>>>>>>>>>>>> with the hw index in order to restore the muxing.
>>>>>>>>>>>>>>> by 'restoring' helper for generic clk_gate, are you
>>>>>>>>>>>>>>> referring to
>>>>>>>>>>>>>>> clk_gate_restore_context API?
>>>>>>>>>>>>>> Yes.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> clk_gate_restore_context is API that's any clk drivers can
>>>>>>>>>>>>>>> use for
>>>>>>>>>>>>>>> clk_gate operation restore for custom gate clk_ops.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> But clk-periph is directly using generic clk_mux ops from
>>>>>>>>>>>>>>> clk_mux
>>>>>>>>>>>>>>> so I
>>>>>>>>>>>>>>> think we should add .restore_context to clk_mux_ops and then
>>>>>>>>>>>>>>> during
>>>>>>>>>>>>>>> clk-periph restore need to invoke mux_ops->restore_context.
>>>>>>>>>>>>>> I'm not sure whether it will be good for every driver that
>>>>>>>>>>>>>> uses
>>>>>>>>>>>>>> generic
>>>>>>>>>>>>>> clk_mux ops. Should be more flexible to have a generic helper
>>>>>>>>>>>>>> function
>>>>>>>>>>>>>> that any driver could use in order to restore the clock's
>>>>>>>>>>>>>> parent.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The clk-periph restoring also includes case of combining
>>>>>>>>>>>>>> divider
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>> parent restoring, so generic helper could be useful in that
>>>>>>>>>>>>>> case
>>>>>>>>>>>>>> as well.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> It also looks like you could actually use the
>>>>>>>>>>>>>> clk_gate_restore_context()
>>>>>>>>>>>>>> instead of manually saving the clock's enable-state, couldn't
>>>>>>>>>>>>>> you?
>>>>>>>>>>>>> ok for clk_mux, can add generic clk_mux_restore_context API
>>>>>>>>>>>>> rather
>>>>>>>>>>>>> than
>>>>>>>>>>>>> using restore_context in clk_ops and will invoke that during
>>>>>>>>>>>>> clk_periph
>>>>>>>>>>>>> restore.
>>>>>>>>>>>>>
>>>>>>>>> digging thru looks like for clk_periph source restore instead of
>>>>>>>>> clk_mux_restore_context, i can directly do clk_hw_get_parent and
>>>>>>>>> clk_set_parent with mux_hw as they invoke mux_ops get/set parent
>>>>>>>>> anyway.
>>>>>>>>> Will do this for periph clk mux
>> Just to be clear, clk_mux don't have cached parent. get_parent is by
>> register read. So, cant directly use get_parent and then set during
>> restore.
>>
>> So will create both clk_mux_save/restore_context in generic clk driver
>> and will invoke them during tegra peripheral clock suspend/resume.
> Why MUX clock doesn't have a cached parent? What MUX clock you're
> talking about?
>
> [snip]

Please ignore got it.

Will send next version after giving few more days for feedback.

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