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Date:   Fri, 14 Jun 2019 10:50:18 +0200
From:   Lukasz Luba <l.luba@...tner.samsung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>, linux-clk@...r.kernel.org,
        mturquette@...libre.com, sboyd@...nel.org,
        Bartłomiej Żołnierkiewicz 
        <b.zolnierkie@...sung.com>, kgene@...nel.org,
        Chanwoo Choi <cw00.choi@...sung.com>,
        kyungmin.park@...sung.com,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        s.nawrocki@...sung.com, myungjoo.ham@...sung.com,
        keescook@...omium.org, tony@...mide.com, jroedel@...e.de,
        treding@...dia.com, digetx@...il.com, gregkh@...uxfoundation.org,
        willy.mh.wolff.ml@...il.com
Subject: Re: [PATCH v9 08/13] drivers: memory: add DMC driver for Exynos5422

Hi Krzysztof,

On 6/11/19 8:18 AM, Krzysztof Kozlowski wrote:
> On Fri, 7 Jun 2019 at 16:35, Lukasz Luba <l.luba@...tner.samsung.com> wrote:
>>
>> This patch adds driver for Exynos5422 Dynamic Memory Controller.
>> The driver provides support for dynamic frequency and voltage scaling for
>> DMC and DRAM. It supports changing timings of DRAM running with different
>> frequency. There is also an algorithm to calculate timigns based on
>> memory description provided in DT.
>> The patch also contains needed MAINTAINERS file update.
>>
>> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
>> ---
>>   MAINTAINERS                             |    8 +
>>   drivers/memory/samsung/Kconfig          |   17 +
>>   drivers/memory/samsung/Makefile         |    1 +
>>   drivers/memory/samsung/exynos5422-dmc.c | 1261 +++++++++++++++++++++++
>>   4 files changed, 1287 insertions(+)
>>   create mode 100644 drivers/memory/samsung/exynos5422-dmc.c
> 
> (...)
> 
>> +
>> +/**
>> + * exynos5_performance_counters_init() - Initializes performance DMC's counters
>> + * @dmc:       DMC for which it does the setup
>> + *
>> + * Initialization of performance counters in DMC for estimating usage.
>> + * The counter's values are used for calculation of a memory bandwidth and based
>> + * on that the governor changes the frequency.
>> + * The counters are not used when the governor is GOVERNOR_USERSPACE.
>> + */
>> +static int exynos5_performance_counters_init(struct exynos5_dmc *dmc)
>> +{
>> +       int counters_size;
>> +       int ret, i;
>> +
>> +       dmc->num_counters = devfreq_event_get_edev_count(dmc->dev);
>> +       if (dmc->num_counters < 0) {
>> +               dev_err(dmc->dev, "could not get devfreq-event counters\n");
>> +               return dmc->num_counters;
>> +       }
>> +
>> +       counters_size = sizeof(struct devfreq_event_dev) * dmc->num_counters;
>> +       dmc->counter = devm_kzalloc(dmc->dev, counters_size, GFP_KERNEL);
>> +       if (!dmc->counter)
>> +               return -ENOMEM;
>> +
>> +       for (i = 0; i < dmc->num_counters; i++) {
>> +               dmc->counter[i] =
>> +                       devfreq_event_get_edev_by_phandle(dmc->dev, i);
>> +               if (IS_ERR_OR_NULL(dmc->counter[i]))
>> +                       return -EPROBE_DEFER;
>> +       }
>> +
>> +       ret = exynos5_counters_enable_edev(dmc);
>> +       if (ret < 0) {
>> +               dev_err(dmc->dev, "could not enable event counter\n");
>> +               return ret;
>> +       }
>> +
>> +       ret = exynos5_counters_set_event(dmc);
>> +       if (ret < 0) {
>> +               dev_err(dmc->dev, "counld not set event counter\n");
> 
> Missing cleanup - edev counters disable.
right
> 
>> +               return ret;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +/**
>> + * exynos5_dmc_set_pause_on_switching() - Controls a pause feature in DMC
>> + * @dmc:       device which is used for changing this feature
>> + * @set:       a boolean state passing enable/disable request
>> + *
>> + * There is a need of pausing DREX DMC when divider or MUX in clock tree
>> + * changes its configuration. In such situation access to the memory is blocked
>> + * in DMC automatically. This feature is used when clock frequency change
>> + * request appears and touches clock tree.
>> + */
>> +static inline int exynos5_dmc_set_pause_on_switching(struct exynos5_dmc *dmc)
>> +{
>> +       unsigned int val;
>> +       int ret;
>> +
>> +       ret = regmap_read(dmc->clk_regmap, CDREX_PAUSE, &val);
>> +       if (ret)
>> +               return ret;
>> +
>> +       val |= 1UL;
>> +       regmap_write(dmc->clk_regmap, CDREX_PAUSE, val);
>> +
>> +       return 0;
>> +}
>> +
>> +/**
>> + * exynos5_dmc_probe() - Probe function for the DMC driver
>> + * @pdev:      platform device for which the driver is going to be initialized
>> + *
>> + * Initialize basic components: clocks, regulators, performance counters, etc.
>> + * Read out product version and based on the information setup
>> + * internal structures for the controller (frequency and voltage) and for DRAM
>> + * memory parameters: timings for each operating frequency.
>> + * Register new devfreq device for controlling DVFS of the DMC.
>> + */
>> +static int exynos5_dmc_probe(struct platform_device *pdev)
>> +{
>> +       int ret = 0;
>> +       struct device *dev = &pdev->dev;
>> +       struct device_node *np = dev->of_node;
>> +       struct exynos5_dmc *dmc;
>> +       struct resource *res;
>> +
>> +       dmc = devm_kzalloc(dev, sizeof(*dmc), GFP_KERNEL);
>> +       if (!dmc)
>> +               return -ENOMEM;
>> +
>> +       mutex_init(&dmc->lock);
>> +
>> +       dmc->dev = dev;
>> +       platform_set_drvdata(pdev, dmc);
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       dmc->base_drexi0 = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(dmc->base_drexi0))
>> +               return PTR_ERR(dmc->base_drexi0);
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>> +       dmc->base_drexi1 = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(dmc->base_drexi1))
>> +               return PTR_ERR(dmc->base_drexi1);
>> +
>> +       dmc->clk_regmap = syscon_regmap_lookup_by_phandle(np,
>> +                               "samsung,syscon-clk");
>> +       if (IS_ERR(dmc->clk_regmap))
>> +               return PTR_ERR(dmc->clk_regmap);
>> +
>> +       ret = exynos5_init_freq_table(dmc, &exynos5_dmc_df_profile);
>> +       if (ret) {
>> +               dev_warn(dev, "couldn't initialize frequency settings\n");
>> +               return ret;
>> +       }
>> +
>> +       dmc->vdd_mif = devm_regulator_get(dev, "vdd");
>> +       if (IS_ERR(dmc->vdd_mif)) {
>> +               ret = PTR_ERR(dmc->vdd_mif);
>> +               return ret;
>> +       }
>> +
>> +       ret = exynos5_dmc_init_clks(dmc);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = of_get_dram_timings(dmc);
>> +       if (ret) {
>> +               dev_warn(dev, "couldn't initialize timings settings\n");
> 
> goto remove_clocks;
OK
> 
>> +               return ret;
>> +       }
>> +
>> +       ret = exynos5_performance_counters_init(dmc);
>> +       if (ret) {
>> +               dev_warn(dev, "couldn't probe performance counters\n");
>> +               goto remove_clocks;
>> +       }
>> +
>> +       ret = exynos5_dmc_set_pause_on_switching(dmc);
>> +       if (ret) {
>> +               dev_warn(dev, "couldn't get access to PAUSE register\n");
>> +               goto remove_clocks;
> 
> goto err_devfreq_add;
Agree.

Thank you for the review.

Regards,
Lukasz

> Best regards,
> Krzysztof
> 
>> +       }
>> +
>> +       /*
>> +        * Setup default thresholds for the devfreq governor.
>> +        * The values are chosen based on experiments.
>> +        */
>> +       dmc->gov_data.upthreshold = 30;
>> +       dmc->gov_data.downdifferential = 5;
>> +
>> +       dmc->df = devm_devfreq_add_device(dev, &exynos5_dmc_df_profile,
>> +                                         DEVFREQ_GOV_USERSPACE,
>> +                                         &dmc->gov_data);
>> +
>> +       if (IS_ERR(dmc->df)) {
>> +               ret = PTR_ERR(dmc->df);
>> +               goto err_devfreq_add;
>> +       }
>> +
>> +       dev_info(dev, "DMC initialized\n");
>> +
>> +       return 0;
>> +
>> +err_devfreq_add:
>> +       exynos5_counters_disable_edev(dmc);
>> +remove_clocks:
>> +       clk_disable_unprepare(dmc->mout_bpll);
>> +       clk_disable_unprepare(dmc->fout_bpll);
>> +
>> +       return ret;
>> +}
>> +
>>
> 
> 

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