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Date: Thu, 3 May 2018 14:39:57 +0530
From: Taniya Das <tdas@...eaurora.org>
To: Stephen Boyd <sboyd@...nel.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...eaurora.org>
Cc: Andy Gross <andy.gross@...aro.org>,
David Brown <david.brown@...aro.org>,
Rajendra Nayak <rnayak@...eaurora.org>,
Odelu Kukatla <okukatla@...eaurora.org>,
Amit Nischal <anischal@...eaurora.org>,
linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] clk: qcom: gdsc: Add support to poll CFG register to
check GDSC state
Hello Stephen,
I have tested the below patch & didn't see any issues.
On 5/2/2018 12:27 PM, Stephen Boyd wrote:
> Quoting Taniya Das (2018-04-30 22:03:33)
>> @@ -45,15 +50,28 @@
>>
>> #define domain_to_gdsc(domain) container_of(domain, struct gdsc, pd)
>>
>> -static int gdsc_is_enabled(struct gdsc *sc, unsigned int reg)
>> +static int gdsc_is_enabled(struct gdsc *sc, bool en)
>> {
>> + unsigned int reg;
>> u32 val;
>> int ret;
>>
>> + if (sc->flags & POLL_CFG_GDSCR)
>> + reg = sc->gdscr + CFG_GDSCR_OFFSET;
>> + else
>> + reg = sc->gds_hw_ctrl ? sc->gds_hw_ctrl : sc->gdscr;
>> +
>> ret = regmap_read(sc->regmap, reg, &val);
>> if (ret)
>> return ret;
>>
>> + if (sc->flags & POLL_CFG_GDSCR) {
>> + if (en)
>> + return !!(val & GDSC_POWER_UP_COMPLETE);
>> + else
>> + return !(val & GDSC_POWER_DOWN_COMPLETE);
>
> This is confusing, but also is correct, because this function is
> returning if the gdsc is enabled or not, and that also happens to be
> false when the gdsc is not enabled and this bit is set.
>
>> + }
>> +
>> return !!(val & PWR_ON_MASK);
>> }
>>
>> @@ -64,17 +82,17 @@ static int gdsc_hwctrl(struct gdsc *sc, bool en)
>> return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
>> }
>>
>> -static int gdsc_poll_status(struct gdsc *sc, unsigned int reg, bool en)
>> +static int gdsc_poll_status(struct gdsc *sc, bool en)
>> {
>> ktime_t start;
>>
>> start = ktime_get();
>> do {
>> - if (gdsc_is_enabled(sc, reg) == en)
>> + if (gdsc_is_enabled(sc, en) == en)
>
> I still don't like this == en logic. How about this patch on top? If you
> can test it out, I'll merge your patch and then my patch to make this
> all easier to read. Note that I changed the off case for
> POWER_DOWN_COMPLETE to be a double negation.
>
> ---8<---
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 2a6b0ff7d451..4696e241db89 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -50,7 +50,13 @@
>
> #define domain_to_gdsc(domain) container_of(domain, struct gdsc, pd)
>
> -static int gdsc_is_enabled(struct gdsc *sc, bool en)
> +enum gdsc_status {
> + GDSC_OFF,
> + GDSC_ON
> +};
> +
> +/* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
> +static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
> {
> unsigned int reg;
> u32 val;
> @@ -58,21 +64,32 @@ static int gdsc_is_enabled(struct gdsc *sc, bool en)
>
> if (sc->flags & POLL_CFG_GDSCR)
> reg = sc->gdscr + CFG_GDSCR_OFFSET;
> + else if (sc->gds_hw_ctrl)
> + reg = sc->gds_hw_ctrl;
> else
> - reg = sc->gds_hw_ctrl ? sc->gds_hw_ctrl : sc->gdscr;
> + reg = sc->gdscr;
>
> ret = regmap_read(sc->regmap, reg, &val);
> if (ret)
> return ret;
>
> if (sc->flags & POLL_CFG_GDSCR) {
> - if (en)
> + switch (status) {
> + case GDSC_ON:
> return !!(val & GDSC_POWER_UP_COMPLETE);
> - else
> - return !(val & GDSC_POWER_DOWN_COMPLETE);
> + case GDSC_OFF:
> + return !!(val & GDSC_POWER_DOWN_COMPLETE);
> + }
> + }
> +
> + switch (status) {
> + case GDSC_ON:
> + return !!(val & PWR_ON_MASK);
> + case GDSC_OFF:
> + return !(val & PWR_ON_MASK);
> }
>
> - return !!(val & PWR_ON_MASK);
> + return -EINVAL;
> }
>
> static int gdsc_hwctrl(struct gdsc *sc, bool en)
> @@ -82,33 +99,33 @@ static int gdsc_hwctrl(struct gdsc *sc, bool en)
> return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
> }
>
> -static int gdsc_poll_status(struct gdsc *sc, bool en)
> +static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
> {
> ktime_t start;
>
> start = ktime_get();
> do {
> - if (gdsc_is_enabled(sc, en) == en)
> + if (gdsc_check_status(sc, status))
> return 0;
> } while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US);
>
> - if (gdsc_is_enabled(sc, en) == en)
> + if (gdsc_check_status(sc, status))
> return 0;
>
> return -ETIMEDOUT;
> }
>
> -static int gdsc_toggle_logic(struct gdsc *sc, bool en)
> +static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
> {
> int ret;
> - u32 val = en ? 0 : SW_COLLAPSE_MASK;
> + u32 val = (status == GDSC_ON) ? 0 : SW_COLLAPSE_MASK;
>
> ret = regmap_update_bits(sc->regmap, sc->gdscr, SW_COLLAPSE_MASK, val);
> if (ret)
> return ret;
>
> /* If disabling votable gdscs, don't poll on status */
> - if ((sc->flags & VOTABLE) && !en) {
> + if ((sc->flags & VOTABLE) && status == GDSC_OFF) {
> /*
> * Add a short delay here to ensure that an enable
> * right after it was disabled does not put it in an
> @@ -118,7 +135,7 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en)
> return 0;
> }
>
> - if (sc->gds_hw_ctrl)
> + if (sc->gds_hw_ctrl) {
> /*
> * The gds hw controller asserts/de-asserts the status bit soon
> * after it receives a power on/off request from a master.
> @@ -130,8 +147,9 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en)
> * and polling the status bit.
> */
> udelay(1);
> + }
>
> - return gdsc_poll_status(sc, en);
> + return gdsc_poll_status(sc, status);
> }
>
> static inline int gdsc_deassert_reset(struct gdsc *sc)
> @@ -210,7 +228,7 @@ static int gdsc_enable(struct generic_pm_domain *domain)
> gdsc_deassert_clamp_io(sc);
> }
>
> - ret = gdsc_toggle_logic(sc, true);
> + ret = gdsc_toggle_logic(sc, GDSC_ON);
> if (ret)
> return ret;
>
> @@ -266,7 +284,7 @@ static int gdsc_disable(struct generic_pm_domain *domain)
> */
> udelay(1);
>
> - ret = gdsc_poll_status(sc, true);
> + ret = gdsc_poll_status(sc, GDSC_ON);
> if (ret)
> return ret;
> }
> @@ -274,7 +292,7 @@ static int gdsc_disable(struct generic_pm_domain *domain)
> if (sc->pwrsts & PWRSTS_OFF)
> gdsc_clear_mem_on(sc);
>
> - ret = gdsc_toggle_logic(sc, false);
> + ret = gdsc_toggle_logic(sc, GDSC_OFF);
> if (ret)
> return ret;
>
> @@ -303,12 +321,12 @@ static int gdsc_init(struct gdsc *sc)
>
> /* Force gdsc ON if only ON state is supported */
> if (sc->pwrsts == PWRSTS_ON) {
> - ret = gdsc_toggle_logic(sc, true);
> + ret = gdsc_toggle_logic(sc, GDSC_ON);
> if (ret)
> return ret;
> }
>
> - on = gdsc_is_enabled(sc, true);
> + on = gdsc_check_status(sc, GDSC_ON);
> if (on < 0)
> return on;
>
>
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