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Date: Mon, 7 Jan 2019 12:48:31 +0530
From: Taniya Das <tdas@...eaurora.org>
To: Matthias Kaehlcke <mka@...omium.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
Stephen Boyd <sboyd@...nel.org>,
Rajendra Nayak <rnayak@...eaurora.org>,
devicetree@...r.kernel.org, robh@...nel.org,
skannan@...eaurora.org, linux-arm-msm@...r.kernel.org,
amit.kucheria@...aro.org, evgreen@...gle.com
Subject: Re: [PATCH v1] cpufreq: qcom: Read voltage LUT and populate OPP
On 12/27/2018 1:02 AM, Matthias Kaehlcke wrote:
> Hi Taniya,
>
> On Mon, Dec 24, 2018 at 12:29:18AM +0530, Taniya Das wrote:
>> Hello Matthias,
>>
>> Thanks for your review comments.
>>
>> On 12/22/2018 2:27 AM, Matthias Kaehlcke wrote:
>>> Hi Taniya,
>>>
>>> On Fri, Dec 21, 2018 at 11:36:48PM +0530, Taniya Das wrote:
>>>> Add support to read the voltage look up table and populate OPP for all
>>>> corresponding CPUS.
>>>>
>>>> Signed-off-by: Taniya Das <tdas@...eaurora.org>
>>>> ---
>>>> drivers/cpufreq/qcom-cpufreq-hw.c | 32 ++++++++++++++++++++++++++++++--
>>>> 1 file changed, 30 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
>>>> index d83939a..7559b87 100644
>>>> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
>>>> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
>>>> @@ -10,18 +10,21 @@
>>>> #include <linux/module.h>
>>>> #include <linux/of_address.h>
>>>> #include <linux/of_platform.h>
>>>> +#include <linux/pm_opp.h>
>>>> #include <linux/slab.h>
>>>>
>>>> #define LUT_MAX_ENTRIES 40U
>>>> #define LUT_SRC GENMASK(31, 30)
>>>> #define LUT_L_VAL GENMASK(7, 0)
>>>> #define LUT_CORE_COUNT GENMASK(18, 16)
>>>> +#define LUT_VOLT GENMASK(11, 0)
>>>> #define LUT_ROW_SIZE 32
>>>> #define CLK_HW_DIV 2
>>>>
>>>> /* Register offsets */
>>>> #define REG_ENABLE 0x0
>>>> -#define REG_LUT_TABLE 0x110
>>>> +#define REG_FREQ_LUT_TABLE 0x110
>>>> +#define REG_VOLT_LUT_TABLE 0x114
>>>
>>> The new names suggest that there is a LUT for frequencies and another
>>> one for voltages. I don't have access to hardware documentation, but
>>> from the code and offsets in this driver it seems there is a single
>>> table at offset 0x110, with a 'row' of 32 bytes per OPP. Within this
>>> row the frequency (and other values) is located at offset 0, the
>>> voltage at offset 4.
>>>
>>> I'd suggest to keep REG_LUT_TABLE, add a define LUT_OFFSET_VOLTAGE/MV
>>> (or similar) and adjust the math in qcom_cpufreq_hw_read_lut() to use
> > > REG_LUT_TABLE as base offset.
>>>
>>
>> These names are as per HW documentation and the math is kept as per the
>> documentation for reading the voltage.
>
> The HW documentation is confusing then and I'm not convinced this
> should be carried over 1:1 to the driver. In any case this
> documentation is only available to a reduced audience, why make it
> harder for everyone else?
>
> I think something like this would be preferable (removed _TABLE suffix,
> since that's already part of LUT):
>
> #define OFFSET_LUT 0x110
> #define REG_FREQ_LUT 0x00
> #define REG_VOLT_LUT 0x04
>
Sorry :( ,This is not the correct interpretation as per the
Documentation. I would leave it as it is. Though I could update the
macro names.
> freq = read(OFFSET_LUT + (LUT_ROW_SIZE * i) + REG_FREQ_LUT);
> volt = read(OFFSET_LUT + (LUT_ROW_SIZE * i) + REG_VOLT_LUT);
>
> or probably better:
>
> row_addr = OFFSET_LUT + (LUT_ROW_SIZE * i);
> freq = read(row_addr + REG_FREQ_LUT);
> volt = read(row_addr + REG_VOLT_LUT);
>
>>>> #define REG_PERF_STATE 0x920
>>>>
>>>> static unsigned long cpu_hw_rate, xo_rate;
>>>> @@ -75,19 +78,26 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>>>> void __iomem *base)
>>>> {
>>>> u32 data, src, lval, i, core_count, prev_cc = 0, prev_freq = 0, freq;
>>>> + u32 volt;
>>>> unsigned int max_cores = cpumask_weight(policy->cpus);
>>>> struct cpufreq_frequency_table *table;
>>>> + unsigned long cpu_r;
>>>
>>> nit: why 'cpu_r' and not just 'cpu'?
>>>
>>> (if it is needed at all, see my comment below)
>>>
Sure, will update it to 'cpu'.
>>>>
>>>> table = kcalloc(LUT_MAX_ENTRIES + 1, sizeof(*table), GFP_KERNEL);
>>>> if (!table)
>>>> return -ENOMEM;
>>>>
>>>> for (i = 0; i < LUT_MAX_ENTRIES; i++) {
>>>> - data = readl_relaxed(base + REG_LUT_TABLE + i * LUT_ROW_SIZE);
>>>> + data = readl_relaxed(base + REG_FREQ_LUT_TABLE +
>>>> + i * LUT_ROW_SIZE);
>>>> src = FIELD_GET(LUT_SRC, data);
>>>> lval = FIELD_GET(LUT_L_VAL, data);
>>>> core_count = FIELD_GET(LUT_CORE_COUNT, data);
>>>>
>>>> + data = readl_relaxed(base + REG_VOLT_LUT_TABLE +
>>>> + i * LUT_ROW_SIZE);
>>>> + volt = FIELD_GET(LUT_VOLT, data) * 1000;
>>>> +
>>>> if (src)
>>>> freq = xo_rate * lval / 1000;
>>>> else
>>>> @@ -123,6 +133,10 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>>>>
>>>> prev_cc = core_count;
>>>> prev_freq = freq;
>>>> +
>>>> + freq *= 1000;
>>>> + for_each_cpu(cpu_r, policy->cpus)
>>>> + dev_pm_opp_add(get_cpu_device(cpu_r), freq, volt);
>>>
>>> Are you sure we want to duplicate the OPP entries for all CPUs in the
>>> cluster? IIUC the frequencies of the cores in a cluster can't be
>>> changed individually, hence the cores should have a shared table. I
>>> think dev_pm_opp_get_sharing_cpus() does what you need.
>>>
>>> You currently also add OPPs for invalid frequencies. From my SDM845
>>> device:
>>>
>>> cat /sys/devices/system/cpu/cpufreq/policy4/scaling_available_freq
>>> => 825600 902400 979200 1056000 1209600 1286400 1363200 1459200
>>> 1536000 1612800 1689600 1766400 1843200 1920000 1996800 2092800
>>> 2169600 2246400 2323200 2400000 2476800 2553600 2649600
>>>
>>> cat /sys/devices/system/cpu/cpufreq/policy4/scaling_boost_frequencies
>>> 2803200
>>>
>>> ls /sys/kernel/debug/opp/cpu4/
>>> opp:1056000000 opp:1612800000 opp:2092800000 opp:2553600000 opp:825600000
>>> opp:1209600000 opp:1689600000 opp:2169600000 opp:2649600000 opp:902400000
>>> opp:1286400000 opp:1766400000 opp:2246400000 opp:2707200000 opp:979200000
>>> opp:1363200000 opp:1843200000 opp:2323200000 opp:2764800000
>>> opp:1459200000 opp:1920000000 opp:2400000000 opp:2784000000
>>> opp:1536000000 opp:1996800000 opp:2476800000 opp:2803200000
>>>
>>> There are OPP entries for 2707200000, 2764800000 and 2784000000 Hz,
>>> however these frequencies appear neither in available_frequencies nor
>>> boost_frequencies.
>>>
>>>> }
>>>>
>>
>> Could you help validating with the patch below?
>>
>>>> table[i].frequency = CPUFREQ_TABLE_END;
>>>> @@ -159,10 +173,18 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>>>> struct device *dev = &global_pdev->dev;
>>>> struct of_phandle_args args;
>>>> struct device_node *cpu_np;
>>>> + struct device *cpu_dev;
>>>> struct resource *res;
>>>> void __iomem *base;
>>>> int ret, index;
>>>>
>>>> + cpu_dev = get_cpu_device(policy->cpu);
>>>> + if (!cpu_dev) {
>>>> + pr_err("%s: failed to get cpu%d device\n", __func__,
>>>> + policy->cpu);
>>>> + return -ENODEV;
>>>> + }
>>>> +
>>>> cpu_np = of_cpu_device_node_get(policy->cpu);
>>>> if (!cpu_np)
>>>> return -EINVAL;
>>>> @@ -205,6 +227,12 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>>>> goto error;
>>>> }
>>>>
>>>> + ret = dev_pm_opp_get_opp_count(cpu_dev);
>>>> + if (ret <= 0) {
>>>> + dev_err(cpu_dev, "OPP table is not ready\n");
>>>> + goto error;
>>>> + }
>>>> +
>>>> policy->fast_switch_possible = true;
>>>>
>>>> return 0;
>>>
>>> I suppose we want to remove the OPPs when the cpufreq driver is
>>> unloaded, looks like dev_pm_opp_cpumask_remove_table() should do the
>>> trick.
>>>
>>> Cheers
>>>
>>> Matthias
>>>
>>
>> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c
>> b/drivers/cpufreq/qcom-cpufreq-hw.c
>> index 7559b87..23338b2 100644
>> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
>> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
>> @@ -81,7 +81,6 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>> u32 volt;
>> unsigned int max_cores = cpumask_weight(policy->cpus);
>> struct cpufreq_frequency_table *table;
>> - unsigned long cpu_r;
>>
>> table = kcalloc(LUT_MAX_ENTRIES + 1, sizeof(*table), GFP_KERNEL);
>> if (!table)
>> @@ -110,6 +109,8 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>> table[i].frequency = freq;
>> dev_dbg(dev, "index=%d freq=%d, core_count %d\n", i,
>> freq, core_count);
>> + dev_pm_opp_add(get_cpu_device(policy->cpu),
>> + freq * 1000, volt);
>
> nit: I'd suggest to put this before dev_dbg() or assign the table
> after dev_dbg(), to keep the actual actions together instead of
> splitting them unnecessarily with a debug log.
>
Sure, would take care of this too.
>> }
>>
>> /*
>> @@ -126,6 +127,8 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>> if (prev_cc != max_cores) {
>> prev->frequency = prev_freq;
>> prev->flags = CPUFREQ_BOOST_FREQ;
>> + dev_pm_opp_add(get_cpu_device(policy->cpu),
>> + prev_freq * 1000, volt);
>> }
>>
>> break;
>> @@ -133,12 +136,9 @@ static int qcom_cpufreq_hw_read_lut(struct device *dev,
>>
>> prev_cc = core_count;
>> prev_freq = freq;
>> -
>> - freq *= 1000;
>> - for_each_cpu(cpu_r, policy->cpus)
>> - dev_pm_opp_add(get_cpu_device(cpu_r), freq, volt);
>> }
>>
>> + dev_pm_opp_set_sharing_cpus(get_cpu_device(policy->cpu),
>> policy->cpus);
>
> nit: since the loop above first initializes the table and then adds
> the OPP it would be slightly more consistent to also finish the
> table business first here and then handle the OPPs. Shouldn't make a
> functional difference though, just a suggestion.
>
Sure, will do it accordingly.
>> table[i].frequency = CPUFREQ_TABLE_END;
>> policy->freq_table = table;
>>
>> @@ -245,6 +245,7 @@ static int qcom_cpufreq_hw_cpu_exit(struct
>> cpufreq_policy *policy)
>> {
>> void __iomem *base = policy->driver_data - REG_PERF_STATE;
>>
>> + dev_pm_opp_cpumask_remove_table(policy->cpus);
>> kfree(policy->freq_table);
>> devm_iounmap(&global_pdev->dev, base);
>>
>
> Looks good to me except for the nits.
>
> Unbinding the device ("echo 17d43000.cpufreq > /sys/bus/platform/drivers/qcom-cpufreq-hw/unbind")
> results in a similar lockdep spat as the one reported earlier by
> Stephen (https://lore.kernel.org/patchwork/patch/1024546/#1209031),
> this time involving 'dev_pm_opp_cpumask_remove_table', however I don't
> think this an issue introduced by this patch.
>
> Thanks
>
> Matthias
>
Thanks for testing out the patch.
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