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

[Dmitry Osipenko <digetx@xxxxxxxxx>]

04.08.2019 2:44, Sowjanya Komatineni пишет:
> 
> On 8/3/19 10:01 AM, Sowjanya Komatineni wrote:
>>
>> 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@xxxxxxxxxx>
>>>>>>>>>>>>>>>>>>>>>>> Signed-off-by: Sowjanya Komatineni
>>>>>>>>>>>>>>>>>>>>>>> <skomatineni@xxxxxxxxxx>
>>>>>>>>>>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>>>>>>>>>>> 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.
>>
> Couple of issues:
> 
> 1.) I see clk-tegra-periph driver periph_clks init_data entries for some
> peripherals are not correct for Tegra 114 and later chips.
> 
> Eg I2C TEGRA_INIT_DATA_TABLE entries in clk-tegra-periph are used for all Tegra
> chipsets currently in the driver.
> 
> These entries are using MUX shift of 30 and MUX mask only for 2 bits which is
> correct for T30 and prior.
> But for later Tegra chips, it should be MUX shift 29 and MASK(3).
> 
> Also, I2C parent idx entries in mux_pllp_clkm_idx are different from Tegra114
> onwards.
> 
> As we are using only PLLP and CLKM sources only for I2C, their corresponding mux
> values from register spec by using upper 2 bits for T114 onwards match actual 2
> bits of MUX value on T30 and prior.
> 
> Not sure if this something known pending to port actual clock MUX table changes
> for Tegra114 onwards?
> 
> Or
> 
> Are we purposely using upper 2 bits only for clock source for T114 and later as
> the upper 2 bit values of the limited clock source we are using match with
> previous Tegra peripheral clock source mux values?

The actual hardware values are compatible on all Tegra SoCs and PLLC2 and PLLC3
are just unused on T114+, so should be okay.

> Peter/Thierry, Can you please help comment on this?
> 
> 
> 2.) Other issue is regarding using clk_set_parent directly during clk_peripheral
> restore is clk_core_set_parent checks new parent with current parent and if its
> same, it just returns as success which is good in normal operation.
> 
> But during restore, we can't use clk_set_parent as new parent is from
> clk_get_parent on restore and this is same as cached parent.
> 
> So clk_set_parent returns 0 but acutal register value for clk source is different
> as it gets reset on SC7 entry/exit and to restore need to invoke mux_ops
> set_parent with parent_index.
> 
> So this need parent index for cached parent and without using context variable to
> store this, need an API like you were originally suggesting for get_parent_index
> to get parent index for the specified parent clk_hw.
> 
> As we decided not to use save/restore for clk_mux ops as its generic for other
> drivers, looks like we need get_parent_index API to use for restoring peripheral
> source and use this with clk_mux_ops set_parent.
> 
> clk core driver already has clk_fetch_parent_index but is it OK to export this?
> 
> Otherwise, will create separate API in clk driver which returns parent index from
> parent clk_hw by using this existing clk_fetch_parent_index so this API can be
> used by other drivers.

The clk_fetch_parent_index can't be used directly as you can see because it uses
clk_core which is internal to clk.c, you'll need to make a wrapper for getting the
cached index.

Something like this:

int clk_hw_get_parent_index(struct clk_hw *hw, struct *parent_hw)
{
	if (!hw || !parent_hw)
		return -EINVAL;

	return clk_fetch_parent_index(hw->core, parent_hw->core);
}