linux-kernel - Re: [PATCH v8 05/21] clk: tegra: pll: Save and restore pll context

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Date:   Sun, 11 Aug 2019 20:24:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.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, rjw@...ysocki.net,
        viresh.kumar@...aro.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v8 05/21] clk: tegra: pll: Save and restore pll context

09.08.2019 21:50, Sowjanya Komatineni пишет:
> 
> On 8/9/19 10:50 AM, Dmitry Osipenko wrote:
>> 09.08.2019 20:39, Sowjanya Komatineni пишет:
>>> On 8/9/19 4:33 AM, Dmitry Osipenko wrote:
>>>> 09.08.2019 2:46, Sowjanya Komatineni пишет:
>>>>> This patch implements save and restore of PLL context.
>>>>>
>>>>> During system suspend, core power goes off and looses the settings
>>>>> of the Tegra CAR controller registers.
>>>>>
>>>>> So during suspend entry pll context is stored and on resume it is
>>>>> restored back along with its state.
>>>>>
>>>>> Acked-by: Thierry Reding <treding@...dia.com>
>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>>>>> ---
>>>>>    drivers/clk/tegra/clk-pll.c | 88 ++++++++++++++++++++++++++++-----------------
>>>>>    drivers/clk/tegra/clk.h     |  2 ++
>>>>>    2 files changed, 58 insertions(+), 32 deletions(-)
>>>>>
>>>>> diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
>>>>> index 1583f5fc992f..e52add2bbdbb 100644
>>>>> --- a/drivers/clk/tegra/clk-pll.c
>>>>> +++ b/drivers/clk/tegra/clk-pll.c
>>>>> @@ -1008,6 +1008,28 @@ static unsigned long clk_plle_recalc_rate(struct clk_hw *hw,
>>>>>        return rate;
>>>>>    }
>>>>>    +static void tegra_clk_pll_restore_context(struct clk_hw *hw)
>>>>> +{
>>>>> +    struct tegra_clk_pll *pll = to_clk_pll(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);
>>>>> +    u32 val;
>>>>> +
>>>>> +    if (clk_pll_is_enabled(hw))
>>>>> +        return;
>>>>> +
>>>>> +    if (pll->params->set_defaults)
>>>>> +        pll->params->set_defaults(pll);
>>>>> +
>>>>> +    clk_pll_set_rate(hw, rate, parent_rate);
>>>>> +
>>>>> +    if (!__clk_get_enable_count(hw->clk))
>>>> What about orphaned clocks? Is enable_count > 0 for them?
>>> There are no orphaned pll clocks.
>> Sorry, I meant the "clk_ignore_unused".
> 
> clocks with CLK_IGNORE_UNUSED are taken care by clk driver.
> 
> clk_disable_unused checks for clocks with this flag and if they are not enabled it will
> enable them.
> 
> So by the time suspend happens enable_count is > 0

Okay.