Re: [PATCH v7 07/20] clk: tegra: clk-periph: Add save and restore support

[Dmitry Osipenko]

03.08.2019 2:51, Sowjanya Komatineni ÐÐÑÐÑ:
> 
> On 8/2/19 2:15 PM, Dmitry Osipenko wrote:
>> 02.08.2019 23:32, Sowjanya Komatineni ÐÐÑÐÑ:
>>> On 8/2/19 1:17 PM, Dmitry Osipenko wrote:
>>>> 02.08.2019 23:13, Dmitry Osipenko ÐÐÑÐÑ:
>>>>> 02.08.2019 21:33, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>>> On 8/2/19 5:38 AM, Dmitry Osipenko wrote:
>>>>>>> 02.08.2019 2:49, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>>>>> 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 ÐÐÑÐÑ:
>>>>>>>>>>>> On 8/1/19 1:17 PM, Dmitry Osipenko wrote:
>>>>>>>>>>>>> 01.08.2019 22:42, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>>>>>>>>>>> On 8/1/19 12:00 PM, Dmitry Osipenko wrote:
>>>>>>>>>>>>>>> 01.08.2019 20:58, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>>>>>>>>>>>>> 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 ÐÐÑÐÑ:
>>>>>>>>>>>>>>>>>>> 31.07.2019 3:20, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>>>>>>>>>>>>>>>>> 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@xxxxxxxxxx>
>>>>>>>>>>>>>>>>>>>> Signed-off-by: Sowjanya Komatineni
>>>>>>>>>>>>>>>>>>>> <skomatineni@xxxxxxxxxx>
>>>>>>>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ drivers/clk/tegra/clk-periph-fixed.c | 33
>>>>>>>>>>>>>>>>>>>> ++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>>  drivers/clk/tegra/clk-periph-gate.c | 34
>>>>>>>>>>>>>>>>>>>> +++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ drivers/clk/tegra/clk-periph.cÂÂÂÂÂÂ | 37
>>>>>>>>>>>>>>>>>>>> ++++++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ drivers/clk/tegra/clk-sdmmc-mux.cÂÂÂ | 28
>>>>>>>>>>>>>>>>>>>> +++++++++++++++++++++++++++
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ drivers/clk/tegra/clk.hÂÂÂÂÂÂÂÂÂÂÂÂÂ | 6 ++++++
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ 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,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ return (unsigned long)rate;
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ }
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ +static int
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_save_context(struct
>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph_fixed *fixed =
>>>>>>>>>>>>>>>>>>>> to_tegra_clk_periph_fixed(hw);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ u32 mask = 1 << (fixed->num % 32);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ fixed->enb_ctx = readl_relaxed(fixed->base +
>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_reg) &
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂ mask;
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ fixed->rst_ctx = readl_relaxed(fixed->base +
>>>>>>>>>>>>>>>>>>>> fixed->regs->rst_reg) &
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂ mask;
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ return 0;
>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +static void
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_restore_context(struct
>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph_fixed *fixed =
>>>>>>>>>>>>>>>>>>>> to_tegra_clk_periph_fixed(hw);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ u32 mask = 1 << (fixed->num % 32);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ if (fixed->enb_ctx)
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_set_reg);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ else
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>> fixed->regs->enb_clr_reg);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ udelay(2);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ if (!fixed->rst_ctx) {
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ udelay(5); /* reset propogation delay */
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base +
>>>>>>>>>>>>>>>>>>>> fixed->regs->rst_reg);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ }
>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ static const struct clk_ops
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_ops
>>>>>>>>>>>>>>>>>>>> = {
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .is_enabled =
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_is_enabled,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .enable = tegra_clk_periph_fixed_enable,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .disable = tegra_clk_periph_fixed_disable,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .recalc_rate =
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_recalc_rate,
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ .save_context =
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_save_context,
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ .restore_context =
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_fixed_restore_context,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ };
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ Â 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);
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ Â #define read_rst(gate) \
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ readl_relaxed(gate->clk_base +
>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_reg))
>>>>>>>>>>>>>>>>>>>> +#define write_rst_set(val, gate) \
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ writel_relaxed(val, gate->clk_base +
>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_set_reg))
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ #define write_rst_clr(val, gate) \
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ writel_relaxed(val, gate->clk_base +
>>>>>>>>>>>>>>>>>>>> (gate->regs->rst_clr_reg))
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ @@ -110,10 +112,42 @@ static void
>>>>>>>>>>>>>>>>>>>> clk_periph_disable(struct
>>>>>>>>>>>>>>>>>>>> clk_hw *hw)
>>>>>>>>>>>>>>>>>>>> spin_unlock_irqrestore(&periph_ref_lock, flags);
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ }
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ +static int clk_periph_gate_save_context(struct
>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph_gate *gate =
>>>>>>>>>>>>>>>>>>>> to_clk_periph_gate(hw);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ gate->clk_state_ctx = read_enb(gate) &
>>>>>>>>>>>>>>>>>>>> periph_clk_to_bit(gate);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ gate->rst_state_ctx = read_rst(gate) &
>>>>>>>>>>>>>>>>>>>> periph_clk_to_bit(gate);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ return 0;
>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +static void clk_periph_gate_restore_context(struct
>>>>>>>>>>>>>>>>>>>> clk_hw
>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph_gate *gate =
>>>>>>>>>>>>>>>>>>>> to_clk_periph_gate(hw);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ if (gate->clk_state_ctx)
>>>>>>>>>>>>>>>>>>>> + write_enb_set(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ else
>>>>>>>>>>>>>>>>>>>> + write_enb_clr(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ udelay(5);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ if (gate->rst_state_ctx)
>>>>>>>>>>>>>>>>>>>> + write_rst_set(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ else
>>>>>>>>>>>>>>>>>>>> + write_rst_clr(periph_clk_to_bit(gate), gate);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ }
>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ const struct clk_ops
>>>>>>>>>>>>>>>>>>>> tegra_clk_periph_gate_ops = {
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .is_enabled = clk_periph_is_enabled,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .enable = clk_periph_enable,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ .disable = clk_periph_disable,
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ .save_context = clk_periph_gate_save_context,
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ .restore_context =
>>>>>>>>>>>>>>>>>>>> clk_periph_gate_restore_context,
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ };
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ Â 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)
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ gate_ops->disable(gate_hw);
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ }
>>>>>>>>>>>>>>>>>>>> ÂÂÂÂÂÂÂ +static int clk_periph_save_context(struct
>>>>>>>>>>>>>>>>>>>> clk_hw *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph *periph =
>>>>>>>>>>>>>>>>>>>> to_clk_periph(hw);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ const struct clk_ops *gate_ops = periph->gate_ops;
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct clk_hw *gate_hw = &periph->gate.hw;
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
>>>>>>>>>>>>>>>>>>>> +ÂÂÂÂÂÂÂ gate_ops->save_context(gate_hw);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ periph->parent_ctx = clk_periph_get_parent(hw);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ return 0;
>>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +static void clk_periph_restore_context(struct clk_hw
>>>>>>>>>>>>>>>>>>>> *hw)
>>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct tegra_clk_periph *periph =
>>>>>>>>>>>>>>>>>>>> to_clk_periph(hw);
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ const struct clk_ops *gate_ops = periph->gate_ops;
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct clk_hw *gate_hw = &periph->gate.hw;
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ const struct clk_ops *div_ops = periph->div_ops;
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ struct clk_hw *div_hw = &periph->divider.hw;
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ clk_periph_set_parent(hw, periph->parent_ctx);
>>>>>>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>>>>>>> +ÂÂÂ 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]