linux-kernel - Re: [RFC 06/19] devfreq: imx8m-ddrc: Add late system sleep PM ops

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Date:   Wed, 15 Sep 2021 12:37:45 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Abel Vesa <abel.vesa@....com>, Rob Herring <robh@...nel.org>,
        Dong Aisheng <aisheng.dong@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Georgi Djakov <djakov@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc:     Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-serial@...r.kernel.org, NXP Linux Team <linux-imx@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 06/19] devfreq: imx8m-ddrc: Add late system sleep PM ops

Hi,

As I commented on patch5, you keep the OPP list on devicetree file
and then you better to use the 'suspend_opp' property
for setting the highest frequency during suspend/resume.

On 21. 9. 14. 오전 2:38, Abel Vesa wrote:
> Seems that, in order to be able to resume from suspend, the dram rate
> needs to be the highest one available. Therefore, add the late system
> suspend/resume PM ops which set the highest rate on suspend and the
> latest one used before suspending on resume.
> 
> Signed-off-by: Abel Vesa <abel.vesa@....com>
> ---
>   drivers/devfreq/imx8m-ddrc.c | 28 +++++++++++++++++++++++++++-
>   1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/imx8m-ddrc.c b/drivers/devfreq/imx8m-ddrc.c
> index f18a5c3c1c03..f39741b4a0b0 100644
> --- a/drivers/devfreq/imx8m-ddrc.c
> +++ b/drivers/devfreq/imx8m-ddrc.c
> @@ -72,6 +72,8 @@ struct imx8m_ddrc {
>   	struct clk *dram_alt;
>   	struct clk *dram_apb;
>   
> +	unsigned long suspend_rate;
> +	unsigned long resume_rate;
>   	int freq_count;
>   	struct imx8m_ddrc_freq freq_table[IMX8M_DDRC_MAX_FREQ_COUNT];
>   };
> @@ -271,6 +273,22 @@ static int imx8m_ddrc_target(struct device *dev, unsigned long *freq, u32 flags)
>   	return ret;
>   }
>   
> +static int imx8m_ddrc_suspend(struct device *dev)
> +{
> +	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
> +
> +	priv->resume_rate = clk_get_rate(priv->dram_core);
> +
> +	return imx8m_ddrc_target(dev, &priv->suspend_rate, 0);
> +}
> +
> +static int imx8m_ddrc_resume(struct device *dev)
> +{
> +	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
> +
> +	return imx8m_ddrc_target(dev, &priv->resume_rate, 0);
> +}
> +
>   static int imx8m_ddrc_get_cur_freq(struct device *dev, unsigned long *freq)
>   {
>   	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
> @@ -324,6 +342,9 @@ static int imx8m_ddrc_init_freq_info(struct device *dev)
>   
>   		if (dev_pm_opp_add(dev, freq->rate * 250000, 0))
>   			return -ENODEV;
> +
> +		if (index ==  0)
> +			priv->suspend_rate = freq->rate * 250000;
>   	}
>   
>   	return 0;
> @@ -399,11 +420,16 @@ static const struct of_device_id imx8m_ddrc_of_match[] = {
>   };
>   MODULE_DEVICE_TABLE(of, imx8m_ddrc_of_match);
>   
> +static const struct dev_pm_ops imx8m_ddrc_pm_ops = {
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(imx8m_ddrc_suspend, imx8m_ddrc_resume)
> +};
> +
>   static struct platform_driver imx8m_ddrc_platdrv = {
>   	.probe		= imx8m_ddrc_probe,
>   	.driver = {
>   		.name	= "imx8m-ddrc-devfreq",
> -		.of_match_table = imx8m_ddrc_of_match,
> +		.pm = &imx8m_ddrc_pm_ops,
> +		.of_match_table = of_match_ptr(imx8m_ddrc_of_match),
>   	},
>   };
>   module_platform_driver(imx8m_ddrc_platdrv);
> 


-- 
Best Regards,
Samsung Electronics
Chanwoo Choi