linux-kernel - Re: [PATCH v10 7/7] qcom-tgu: Add reset node to initialize

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Message-ID: <e693d33a-5852-451d-b08c-6e822cd1543f@oss.qualcomm.com>
Date: Tue, 27 Jan 2026 10:50:35 +0800
From: Songwei Chai <songwei.chai@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....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 v10 7/7] qcom-tgu: Add reset node to initialize



On 1/13/2026 7:22 PM, Konrad Dybcio wrote:
> On 1/9/26 3:11 AM, 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>
>> ---
> 
> [...]
> 
>> +/* 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)
>> +{
>> +	struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
>> +	unsigned long value;
>> +	int i, j, ret;
>> +
>> +	if (kstrtoul(buf, 0, &value) || value == 0)
>> +		return -EINVAL;
> 
> Your documentation blurb promises that only 1 is accepted, but this is not
> the case. I think the previous additions had a similar flaw

I’ll fix this to only accept 1 and review the previous additions
for similar issues.

> 
>> +
>> +	if (!drvdata->enable) {
> 
> I think this check needs to be made under a lock, otherwise something else
> may pull the plug inbetween
Will move "guard(spinlock)(&drvdata->lock);" before "drvdata->enable" check.
> 
>> +		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);
>> +
>> +	TGU_LOCK(drvdata->base);
> 
> This is tgu_disable()
will use tgu_disable instead.
> 
>> +
>> +	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) */
> 
> One \t too much
will update.
> 
>> +	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;
> 
> This is unreadable, take a pointer to condition_decode[]
sure.
> 
>> +		}
>> +	}
>> +
>> +	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));
> 
> This is similarly difficult to read with almost random indentation
> 

I agree, the indentation hurts readability. I’ll rework this to make the
expression clearer.

> Konrad