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Date: Fri, 10 Nov 2023 14:02:58 +0530
From: Jagadeesh Kona <quic_jkona@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Abel Vesa <abel.vesa@...aro.org>
CC: "Rafael J. Wysocki" <rafael@...nel.org>,
Kevin Hilman <khilman@...nel.org>,
Ulf Hansson <ulf.hansson@...aro.org>,
Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Bjorn Andersson <andersson@...nel.org>,
"Andy Gross" <agross@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
"Michael Turquette" <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Stanimir Varbanov <stanimir.k.varbanov@...il.com>,
Vikash Garodia <quic_vgarodia@...cinc.com>,
Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Taniya Das <tdas@....qualcomm.com>, <linux-pm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
<linux-clk@...r.kernel.org>, <linux-media@...r.kernel.org>
Subject: Re: [PATCH RESEND v3 3/5] clk: qcom: gdsc: Add set and get hwmode
callbacks to switch GDSC mode
On 11/2/2023 2:58 AM, Dmitry Baryshkov wrote:
> On Wed, 1 Nov 2023 at 11:06, Abel Vesa <abel.vesa@...aro.org> wrote:
>>
>> From: Jagadeesh Kona <quic_jkona@...cinc.com>
>>
>> Add support for set and get hwmode callbacks to switch the GDSC between
>> SW and HW modes. Currently, the GDSC is moved to HW control mode
>> using HW_CTRL flag and if this flag is present, GDSC is moved to HW
>> mode as part of GDSC enable itself. The intention is to keep the
>> HW_CTRL flag functionality as is, since many older chipsets still use
>> this flag.
>>
>> Introduce a new HW_CTRL_TRIGGER flag to switch the GDSC back and forth
>> between HW/SW modes dynamically at runtime. If HW_CTRL_TRIGGER flag is
>> present, register set_hwmode_dev callback to switch the GDSC mode which
>> can be invoked from consumer drivers using dev_pm_genpd_set_hwmode
>> function. Unlike HW_CTRL flag, HW_CTRL_TRIGGER won't move the GDSC to HW
>> control mode as part of GDSC enable itself, GDSC will be moved to HW
>> control mode only when consumer driver explicity calls
>> dev_pm_genpd_set_hwmode to switch to HW mode. Also add the
>> dev_pm_genpd_get_hwmode to allow the consumers to read the actual
>> HW/SW mode from hardware.
>
> Can we add two new flags:
> - HW_CTRL_TRIGGER
> - DEFAULT_HW_TRIGGER
>
> And then define HW_CTRL as HW_CTRL_TRIGGER | DEFAULT_HW_TRIGGER ?
>
> This way older platforms will keep existing behaviour, but can
> gradually migrate to the new callbacks?
>
Thanks Dmitry for your review,
The current usecases we have for GDSC's are either use the existing
HW_CTRL flag to switch the GDSC to HW mode in gdsc_enable() and back to
SW mode in gdsc_disable(). The second usecase is don't switch GDSC mode
in gdsc_enable() & gdsc_disable() at all, and switch the GDSC mode only
in new callbacks when consumers explicitly request it using
dev_pm_genpd_set_hwmode(), this can be achieved using the new
HW_CTRL_TRIGGER flag.
By defining HW_CTRL as HW_CTRL_TRIGGER | DEFAULT_HW_TRIGGER, it switches
the GDSC mode both in enable & disable callbacks and in new callbacks as
well. But we currently don't have any usecase that requires this behaviour.
Thanks,
Jagadeesh
>>
>> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.com>
>> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
>> ---
>> drivers/clk/qcom/gdsc.c | 32 ++++++++++++++++++++++++++++++++
>> drivers/clk/qcom/gdsc.h | 1 +
>> 2 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
>> index 5358e28122ab..c763524cd5da 100644
>> --- a/drivers/clk/qcom/gdsc.c
>> +++ b/drivers/clk/qcom/gdsc.c
>> @@ -363,6 +363,34 @@ static int gdsc_disable(struct generic_pm_domain *domain)
>> return 0;
>> }
>>
>> +static int gdsc_set_hwmode(struct generic_pm_domain *domain, struct device *dev, bool mode)
>> +{
>> + struct gdsc *sc = domain_to_gdsc(domain);
>> +
>> + if (sc->rsupply && !regulator_is_enabled(sc->rsupply)) {
>> + pr_err("Cannot set mode while parent is disabled\n");
>> + return -EIO;
>> + }
>> +
>> + return gdsc_hwctrl(sc, mode);
>> +}
>> +
>> +static bool gdsc_get_hwmode(struct generic_pm_domain *domain, struct device *dev)
>> +{
>> + struct gdsc *sc = domain_to_gdsc(domain);
>> + u32 val;
>> + int ret;
>> +
>> + ret = regmap_read(sc->regmap, sc->gdscr, &val);
>> + if (ret)
>> + return ret;
>> +
>> + if (val & HW_CONTROL_MASK)
>> + return true;
>> +
>> + return false;
>> +}
>> +
>> static int gdsc_init(struct gdsc *sc)
>> {
>> u32 mask, val;
>> @@ -451,6 +479,10 @@ static int gdsc_init(struct gdsc *sc)
>> sc->pd.power_off = gdsc_disable;
>> if (!sc->pd.power_on)
>> sc->pd.power_on = gdsc_enable;
>> + if (sc->flags & HW_CTRL_TRIGGER) {
>> + sc->pd.set_hwmode_dev = gdsc_set_hwmode;
>> + sc->pd.get_hwmode_dev = gdsc_get_hwmode;
>> + }
>>
>> ret = pm_genpd_init(&sc->pd, NULL, !on);
>> if (ret)
>> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
>> index 803512688336..1e2779b823d1 100644
>> --- a/drivers/clk/qcom/gdsc.h
>> +++ b/drivers/clk/qcom/gdsc.h
>> @@ -67,6 +67,7 @@ struct gdsc {
>> #define ALWAYS_ON BIT(6)
>> #define RETAIN_FF_ENABLE BIT(7)
>> #define NO_RET_PERIPH BIT(8)
>> +#define HW_CTRL_TRIGGER BIT(9)
>> struct reset_controller_dev *rcdev;
>> unsigned int *resets;
>> unsigned int reset_count;
>>
>> --
>> 2.34.1
>>
>
>
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