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Subject: Re: [PATCH 1/4] clk: qcom: gdsc: Handle GDSC regulator supplies
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>
Cc:     Andy Gross <agross@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Rob Clark <robdclark@gmail.com>
References: <20200319053902.3415984-1-bjorn.andersson@linaro.org>
 <20200319053902.3415984-2-bjorn.andersson@linaro.org>
From:   Taniya Das <tdas@codeaurora.org>
Message-ID: <5dbd8e67-cc9f-631b-0b4f-b45389be83cd@codeaurora.org>
Date:   Tue, 31 Mar 2020 11:05:17 +0530
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Hi Stephen,

I think the upstream design always wanted the client/consumer to enable 
the GPU Rail and then turn ON the GDSC?

Why are we going ahead with adding the support of regulator in the GDSC 
driver?

On 3/19/2020 11:08 AM, Bjorn Andersson wrote:
> Certain GDSCs, such as the GPU_GX on MSM8996, requires that the upstream
> regulator supply is powered in order to be turned on.
> 
> It's not guaranteed that the bootloader will leave these supplies on and
> the driver core will attempt to enable any GDSCs before allowing the
> individual drivers to probe defer on the PMIC regulator driver not yet
> being present.
> 
> So the gdsc driver needs to be made aware of supplying regulators and
> probe defer on their absence, and it needs to enable and disable the
> regulator accordingly.
> 
> Voltage adjustments of the supplying regulator are deferred to the
> client drivers themselves.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>   drivers/clk/qcom/gdsc.c | 24 ++++++++++++++++++++++++
>   drivers/clk/qcom/gdsc.h |  4 ++++
>   2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index a250f59708d8..3528789cc9d0 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -13,6 +13,7 @@
>   #include <linux/regmap.h>
>   #include <linux/reset-controller.h>
>   #include <linux/slab.h>
> +#include <linux/regulator/consumer.h>
>   #include "gdsc.h"
>   
>   #define PWR_ON_MASK		BIT(31)
> @@ -112,6 +113,12 @@ static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
>   	int ret;
>   	u32 val = (status == GDSC_ON) ? 0 : SW_COLLAPSE_MASK;
>   
> +	if (status == GDSC_ON && sc->rsupply) {
> +		ret = regulator_enable(sc->rsupply);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>   	ret = regmap_update_bits(sc->regmap, sc->gdscr, SW_COLLAPSE_MASK, val);
>   	if (ret)
>   		return ret;
> @@ -143,6 +150,13 @@ static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
>   
>   	ret = gdsc_poll_status(sc, status);
>   	WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");
> +
> +	if (!ret && status == GDSC_OFF && sc->rsupply) {
> +		ret = regulator_disable(sc->rsupply);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>   	return ret;
>   }
>   
> @@ -371,6 +385,16 @@ int gdsc_register(struct gdsc_desc *desc,
>   	if (!data->domains)
>   		return -ENOMEM;
>   
> +	/* Resolve any regulator supplies */
> +	for (i = 0; i < num; i++) {
> +		if (!scs[i] || !scs[i]->supply)
> +			continue;
> +
> +		scs[i]->rsupply = devm_regulator_get(dev, scs[i]->supply);
> +		if (IS_ERR(scs[i]->rsupply))
> +			return PTR_ERR(scs[i]->rsupply);
> +	}
> +
>   	data->num_domains = num;
>   	for (i = 0; i < num; i++) {
>   		if (!scs[i])
> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
> index 64cdc8cf0d4d..c36fc26dcdff 100644
> --- a/drivers/clk/qcom/gdsc.h
> +++ b/drivers/clk/qcom/gdsc.h
> @@ -10,6 +10,7 @@
>   #include <linux/pm_domain.h>
>   
>   struct regmap;
> +struct regulator;
>   struct reset_controller_dev;
>   
>   /**
> @@ -52,6 +53,9 @@ struct gdsc {
>   	struct reset_controller_dev	*rcdev;
>   	unsigned int			*resets;
>   	unsigned int			reset_count;
> +
> +	const char 			*supply;
> +	struct regulator		*rsupply;
>   };
>   
>   struct gdsc_desc {
> 

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