linux-kernel - Re: [PATCH v9 7/7] qcom-tgu: Add reset node to initialize

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Message-ID: <ea0183ba-8515-44ad-ab04-fdee22be01c7@oss.qualcomm.com>
Date: Tue, 6 Jan 2026 15:22:31 +0800
From: Songwei Chai <songwei.chai@....qualcomm.com>
To: Jie Gan <jie.gan@....qualcomm.com>, andersson@...nel.org,
        alexander.shishkin@...ux.intel.com, mike.leach@...aro.org,
        suzuki.poulose@....com, james.clark@....com, krzk+dt@...nel.org,
        conor+dt@...nel.org
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, coresight@...ts.linaro.org,
        devicetree@...r.kernel.org, gregkh@...uxfoundation.org
Subject: Re: [PATCH v9 7/7] qcom-tgu: Add reset node to initialize



On 12/25/2025 1:56 PM, Jie Gan wrote:
> 
> 
> On 12/19/2025 2:59 PM, Songwei Chai wrote:
>> Add reset node to initialize the value of
>> priority/condition_decode/condition_select/timer/counter nodes.
>>
>> Signed-off-by: Songwei Chai <songwei.chai@....qualcomm.com>
>> ---
>>   .../ABI/testing/sysfs-bus-amba-devices-tgu    |  7 ++
>>   drivers/hwtracing/qcom/tgu.c                  | 74 +++++++++++++++++++
>>   2 files changed, 81 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu b/ 
>> Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
>> index 010eade0a1c5..0733b3e07b45 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
>> +++ b/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
>> @@ -42,3 +42,10 @@ KernelVersion    6.19
>>   Contact:    Jinlong Mao <jinlong.mao@....qualcomm.com>, Songwei Chai 
>> <songwei.chai@....qualcomm.com>
>>   Description:
>>           (RW) Set/Get the counter value with specific step for TGU.
>> +
>> +What:        /sys/bus/amba/devices/<tgu-name>/reset_tgu
>> +Date:        December 2025
>> +KernelVersion    6.19
>> +Contact:    Jinlong Mao <jinlong.mao@....qualcomm.com>, Songwei Chai 
>> <songwei.chai@....qualcomm.com>
>> +Description:
>> +        (Write) Write 1 to reset the dataset for TGU.
>> diff --git a/drivers/hwtracing/qcom/tgu.c b/drivers/hwtracing/qcom/tgu.c
>> index d4210869556e..5a8c6af9b719 100644
>> --- a/drivers/hwtracing/qcom/tgu.c
>> +++ b/drivers/hwtracing/qcom/tgu.c
>> @@ -425,8 +425,82 @@ static ssize_t enable_tgu_store(struct device *dev,
>>   }
>>   static DEVICE_ATTR_RW(enable_tgu);
>> +/* reset_tgu_store - Reset Trace and Gating Unit (TGU) configuration. */
>> +static ssize_t reset_tgu_store(struct device *dev,
>> +                   struct device_attribute *attr, const char *buf,
>> +                   size_t size)
>> +{
>> +    unsigned long value;
>> +    struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
>> +    int i, j, ret;
>> +
>> +    if (kstrtoul(buf, 0, &value) || value == 0)
>> +        return -EINVAL;
>> +
>> +    if (!drvdata->enable) {
>> +        ret = pm_runtime_get_sync(drvdata->dev);
>> +        if (ret < 0) {
>> +            pm_runtime_put(drvdata->dev);
>> +            return ret;
>> +        }
>> +    }
>> +
>> +    guard(spinlock)(&drvdata->lock);
>> +    TGU_UNLOCK(drvdata->base);
>> +
>> +    writel(0, drvdata->base + TGU_CONTROL);
> 
> Better move TGU_LOCK(drvdata->base) here
Yeah.>
> Thanks,
> Jie
> 
>> +
>> +    if (drvdata->value_table->priority)
>> +        memset(drvdata->value_table->priority, 0,
>> +                MAX_PRIORITY * drvdata->max_step *
>> +                drvdata->max_reg * sizeof(unsigned int));
>> +
>> +    if (drvdata->value_table->condition_decode)
>> +        memset(drvdata->value_table->condition_decode, 0,
>> +                drvdata->max_condition_decode * drvdata->max_step *
>> +                sizeof(unsigned int));
>> +
>> +        /* Initialize all condition registers to NOT(value=0x1000000) */
>> +    for (i = 0; i < drvdata->max_step; i++) {
>> +        for (j = 0; j < drvdata->max_condition_decode; j++) {
>> +            drvdata->value_table
>> +            ->condition_decode[calculate_array_location(
>> +            drvdata, i, TGU_CONDITION_DECODE, j)] =
>> +            0x1000000;
>> +        }
>> +    }
>> +
>> +    if (drvdata->value_table->condition_select)
>> +        memset(drvdata->value_table->condition_select, 0,
>> +                drvdata->max_condition_select * drvdata->max_step *
>> +                sizeof(unsigned int));
>> +
>> +    if (drvdata->value_table->timer)
>> +        memset(drvdata->value_table->timer, 0,
>> +                (drvdata->max_step) *
>> +                (drvdata->max_timer) *
>> +                sizeof(unsigned int));
>> +
>> +    if (drvdata->value_table->counter)
>> +        memset(drvdata->value_table->counter, 0,
>> +                (drvdata->max_step) *
>> +                (drvdata->max_counter) *
>> +                sizeof(unsigned int));
>> +
>> +    dev_dbg(dev, "Coresight-TGU reset complete\n");
>> +
>> +    TGU_LOCK(drvdata->base);
>> +
>> +    drvdata->enable = false;
>> +    pm_runtime_put(drvdata->dev);
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_WO(reset_tgu);
>> +
>>   static struct attribute *tgu_common_attrs[] = {
>>       &dev_attr_enable_tgu.attr,
>> +    &dev_attr_reset_tgu.attr,
>>       NULL,
>>   };
>