linux-kernel - Re: [PATCH v19 3/7] soc: mediatek: SVS: introduce MTK SVS engine

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Date:   Fri, 02 Jul 2021 10:33:17 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Roger Lu <roger.lu@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Enric Balletbo Serra <eballetbo@...il.com>,
        Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Boichat <drinkcat@...gle.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Fan Chen <fan.chen@...iatek.com>,
        HenryC Chen <HenryC.Chen@...iatek.com>,
        YT Lee <yt.lee@...iatek.com>,
        Xiaoqing Liu <Xiaoqing.Liu@...iatek.com>,
        Charles Yang <Charles.Yang@...iatek.com>,
        Angus Lin <Angus.Lin@...iatek.com>,
        Mark Rutland <mark.rutland@....com>,
        Nishanth Menon <nm@...com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH v19 3/7] soc: mediatek: SVS: introduce MTK SVS engine

Hi Roger,

On Fri, 2021-07-02 at 11:12 +0800, Roger Lu wrote:
[...]
> diff --git a/drivers/soc/mediatek/mtk-svs.c b/drivers/soc/mediatek/mtk-svs.c
> new file mode 100644
> index 000000000000..c2fcbc204b1d
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-svs.c
> @@ -0,0 +1,1724 @@
[...]
> +static int svs_suspend(struct device *dev)
> +{
> +	struct svs_platform *svsp = dev_get_drvdata(dev);
> +	struct svs_bank *svsb;
> +	unsigned long flags;
> +	int ret;
> +	u32 idx;
> +
> +	for (idx = 0; idx < svsp->bank_num; idx++) {
> +		svsb = &svsp->banks[idx];
> +
> +		/* Wait if svs_isr() is still in process. */
> +		spin_lock_irqsave(&mtk_svs_lock, flags);
> +		svsp->pbank = svsb;
> +		svs_switch_bank(svsp);
> +		svs_writel(svsp, SVSB_EN_OFF, SVSEN);
> +		svs_writel(svsp, SVSB_INTSTS_CLEAN, INTSTS);
> +		spin_unlock_irqrestore(&mtk_svs_lock, flags);
> +
> +		svsb->suspended = true;
> +		if (svsb->phase != SVSB_PHASE_INIT01) {
> +			svsb->phase = SVSB_PHASE_ERROR;
> +			svs_adjust_pm_opp_volts(svsb, true);
> +		}
> +	}
> +
> +	if (svsp->rst) {

This is not necessary, reset_control_assert() checks for (rstc == NULL)
itself.

> +		ret = reset_control_assert(svsp->rst);
> +		if (ret) {
> +			dev_err(svsp->dev, "cannot assert reset %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	clk_disable_unprepare(svsp->main_clk);
> +
> +	return 0;
> +}
> +
> +static int svs_resume(struct device *dev)
> +{
> +	struct svs_platform *svsp = dev_get_drvdata(dev);
> +	struct svs_bank *svsb;
> +	int ret;
> +	u32 idx;
> +
> +	ret = clk_prepare_enable(svsp->main_clk);
> +	if (ret) {
> +		dev_err(svsp->dev, "cannot enable main_clk, disable svs\n");
> +		return ret;
> +	}
> +
> +	if (svsp->rst) {

Same as above, reset_control_deassert(NULL) will just return 0.

> +		ret = reset_control_deassert(svsp->rst);
> +		if (ret) {
> +			dev_err(svsp->dev, "cannot deassert reset %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	for (idx = 0; idx < svsp->bank_num; idx++) {
> +		svsb = &svsp->banks[idx];
> +		svsb->suspended = false;
> +	}
> +
> +	ret = svs_init02(svsp);
> +	if (ret)
> +		return ret;
> +
> +	svs_mon_mode(svsp);
> +
> +	return 0;
> +}

regards
Philipp