linux-kernel - Re: [PATCH v10 3/7] qcom-tgu: Add signal priority support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f34abcca-6b09-4f6c-96f3-e2295a82284e@oss.qualcomm.com>
Date: Tue, 13 Jan 2026 12:09:17 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Songwei Chai <songwei.chai@....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 3/7] qcom-tgu: Add signal priority support

On 1/9/26 3:11 AM, Songwei Chai wrote:
> Like circuit of a Logic analyzer, in TGU, the requirement could be
> configured in each step and the trigger will be created once the
> requirements are met. Add priority functionality here to sort the
> signals into different priorities. The signal which is wanted could
> be configured in each step's priority node, the larger number means
> the higher priority and the signal with higher priority will be sensed
> more preferentially.
> 
> Signed-off-by: Songwei Chai <songwei.chai@....qualcomm.com>
> ---

[...]

> +static ssize_t tgu_dataset_store(struct device *dev,
> +				 struct device_attribute *attr,
> +				 const char *buf, size_t size)
> +{
> +	struct tgu_drvdata *tgu_drvdata = dev_get_drvdata(dev);
> +	struct tgu_attribute *tgu_attr =
> +		container_of(attr, struct tgu_attribute, attr);
> +	unsigned long val;
> +	int index;
> +
> +	ret = kstrtoul(buf, 0, &val);
> +	if (ret)
> +		return ret;
> +
> +	guard(spinlock)(&tgu_drvdata->lock);
> +	index = calculate_array_location(tgu_drvdata, tgu_attr->step_index,
> +					 tgu_attr->operation_index,
> +					 tgu_attr->reg_num);
> +
> +	tgu_drvdata->value_table->priority[index] = val;
> +	return size;

Style: some functions have a \n before return, some don't. The former
is preferred

> +static umode_t tgu_node_visible(struct kobject *kobject,
> +				struct attribute *attr,
> +				int n)
> +{
> +	struct device *dev = kobj_to_dev(kobject);
> +	struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
> +	struct device_attribute *dev_attr =
> +		container_of(attr, struct device_attribute, attr);
> +	struct tgu_attribute *tgu_attr =
> +		container_of(dev_attr, struct tgu_attribute, attr);
> +	int ret = SYSFS_GROUP_INVISIBLE;
> +
> +	if (tgu_attr->step_index < drvdata->max_step) {
> +		ret = (tgu_attr->reg_num < drvdata->max_reg) ?
> +			attr->mode : 0;
> +	}
> +	return ret;

This is very convoluted

How about:

if (tgu_attr->step_index >= drvdata->max_step)
	return 0;

if (tgu_attr->reg_num >= drvdata->max_reg)
	return 0;

return attr->mode;

?

[...]

> +static void tgu_set_reg_number(struct tgu_drvdata *drvdata)
> +{
> +	int num_sense_input;
> +	int num_reg;
> +	u32 devid;
> +
> +	devid = readl(drvdata->base + TGU_DEVID);
> +
> +	num_sense_input = TGU_DEVID_SENSE_INPUT(devid);
> +	if (((num_sense_input * NUMBER_BITS_EACH_SIGNAL) % LENGTH_REGISTER) == 0)
> +		num_reg = (num_sense_input * NUMBER_BITS_EACH_SIGNAL) / LENGTH_REGISTER;
> +	else
> +		num_reg = ((num_sense_input * NUMBER_BITS_EACH_SIGNAL) / LENGTH_REGISTER) + 1;

num_reg = base case

if (num_sense_input * NUMBER_BITS_EACH_SIGNAL) % LENGTH_REGISTER)
	num_reg++;

?

[...]

> @@ -112,6 +250,8 @@ static int tgu_probe(struct amba_device *adev, const struct amba_id *id)
>  {
>  	struct device *dev = &adev->dev;
>  	struct tgu_drvdata *drvdata;
> +	size_t priority_size;
> +	unsigned int *priority;

reverse-Christmas-tree would be nice


>  	int ret;
>  
>  	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> @@ -127,12 +267,32 @@ static int tgu_probe(struct amba_device *adev, const struct amba_id *id)
>  
>  	spin_lock_init(&drvdata->lock);
>  
> +	tgu_set_reg_number(drvdata);
> +	tgu_set_steps(drvdata);
> +
>  	ret = sysfs_create_groups(&dev->kobj, tgu_attr_groups);
>  	if (ret) {
>  		dev_err(dev, "failed to create sysfs groups: %d\n", ret);
>  		return ret;
>  	}
>  
> +	drvdata->value_table =
> +		devm_kzalloc(dev, sizeof(*drvdata->value_table), GFP_KERNEL);
> +	if (!drvdata->value_table)
> +		return -ENOMEM;
> +
> +	priority_size = MAX_PRIORITY * drvdata->max_reg *
> +			drvdata->max_step *
> +			sizeof(*(drvdata->value_table->priority));
> +
> +	priority = devm_kzalloc(dev, priority_size, GFP_KERNEL);
> +
> +	if (!priority)

stray \n above

[...]

> +#define BMVAL(val, lsb, msb)	((val & GENMASK(msb, lsb)) >> lsb)
> +#define TGU_DEVID_SENSE_INPUT(devid_val) ((int) BMVAL(devid_val, 10, 17))
> +#define TGU_DEVID_STEPS(devid_val) ((int)BMVAL(devid_val, 3, 6))
> +#define NUMBER_BITS_EACH_SIGNAL 4

"TGU_BITS_PER_SIGNAL"

Konrad