linux-kernel - Re: [PATCH v9 07/17] PM / devfreq: tegra30: Support interconnect and OPPs from device-tree

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Date:   Tue, 17 Nov 2020 17:17:28 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>,
        Viresh Kumar <vireshk@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v9 07/17] PM / devfreq: tegra30: Support interconnect and
 OPPs from device-tree

17.11.2020 13:07, Viresh Kumar пишет:
> On 16-11-20, 00:29, Dmitry Osipenko wrote:
>> This patch moves ACTMON driver away from generating OPP table by itself,
>> transitioning it to use the table which comes from device-tree. This
>> change breaks compatibility with older device-trees in order to bring
>> support for the interconnect framework to the driver. This is a mandatory
>> change which needs to be done in order to implement interconnect-based
>> memory DVFS. Users of legacy device-trees will get a message telling that
>> theirs DT needs to be upgraded. Now ACTMON issues memory bandwidth request
>> using dev_pm_opp_set_bw(), instead of driving EMC clock rate directly.
>>
>> Tested-by: Peter Geis <pgwipeout@...il.com>
>> Tested-by: Nicolas Chauvet <kwizart@...il.com>
>> Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 86 ++++++++++++++++---------------
>>  1 file changed, 44 insertions(+), 42 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index 38cc0d014738..ed6d4469c8c7 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -19,6 +19,8 @@
>>  #include <linux/reset.h>
>>  #include <linux/workqueue.h>
>>  
>> +#include <soc/tegra/fuse.h>
>> +
>>  #include "governor.h"
>>  
>>  #define ACTMON_GLB_STATUS					0x0
>> @@ -155,6 +157,7 @@ struct tegra_devfreq_device {
>>  
>>  struct tegra_devfreq {
>>  	struct devfreq		*devfreq;
>> +	struct opp_table	*opp_table;
>>  
>>  	struct reset_control	*reset;
>>  	struct clk		*clock;
>> @@ -612,34 +615,19 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>>  static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>>  				u32 flags)
>>  {
>> -	struct tegra_devfreq *tegra = dev_get_drvdata(dev);
>> -	struct devfreq *devfreq = tegra->devfreq;
>>  	struct dev_pm_opp *opp;
>> -	unsigned long rate;
>> -	int err;
>> +	int ret;
>>  
>>  	opp = devfreq_recommended_opp(dev, freq, flags);
>>  	if (IS_ERR(opp)) {
>>  		dev_err(dev, "Failed to find opp for %lu Hz\n", *freq);
>>  		return PTR_ERR(opp);
>>  	}
>> -	rate = dev_pm_opp_get_freq(opp);
>> -	dev_pm_opp_put(opp);
>> -
>> -	err = clk_set_min_rate(tegra->emc_clock, rate * KHZ);
>> -	if (err)
>> -		return err;
>> -
>> -	err = clk_set_rate(tegra->emc_clock, 0);
>> -	if (err)
>> -		goto restore_min_rate;
>>  
>> -	return 0;
>> -
>> -restore_min_rate:
>> -	clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
>> +	ret = dev_pm_opp_set_bw(dev, opp);
>> +	dev_pm_opp_put(opp);
>>  
>> -	return err;
>> +	return ret;
>>  }
>>  
>>  static int tegra_devfreq_get_dev_status(struct device *dev,
>> @@ -655,7 +643,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
>>  	stat->private_data = tegra;
>>  
>>  	/* The below are to be used by the other governors */
>> -	stat->current_frequency = cur_freq;
>> +	stat->current_frequency = cur_freq * KHZ;
>>  
>>  	actmon_dev = &tegra->devices[MCALL];
>>  
>> @@ -705,7 +693,12 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
>>  		target_freq = max(target_freq, dev->target_freq);
>>  	}
>>  
>> -	*freq = target_freq;
>> +	/*
>> +	 * tegra-devfreq driver operates with KHz units, while OPP table
>> +	 * entries use Hz units. Hence we need to convert the units for the
>> +	 * devfreq core.
>> +	 */
>> +	*freq = target_freq * KHZ;
>>  
>>  	return 0;
>>  }
>> @@ -774,6 +767,7 @@ static struct devfreq_governor tegra_devfreq_governor = {
>>  
>>  static int tegra_devfreq_probe(struct platform_device *pdev)
>>  {
>> +	u32 hw_version = BIT(tegra_sku_info.soc_speedo_id);
>>  	struct tegra_devfreq_device *dev;
>>  	struct tegra_devfreq *tegra;
>>  	struct devfreq *devfreq;
>> @@ -781,6 +775,13 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	long rate;
>>  	int err;
>>  
>> +	/* legacy device-trees don't have OPP table and must be updated */
>> +	if (!device_property_present(&pdev->dev, "operating-points-v2")) {
>> +		dev_err(&pdev->dev,
>> +			"OPP table not found, please update your device tree\n");
>> +		return -ENODEV;
>> +	}
>> +
> 
> You forgot to remove this ?

Yes, good catch. I'm planning to replace this code with a common helper
sometime soon, so if there won't be another reasons to make a new
revision, then I'd prefer to keep it as-is for now.