Re: [PATCH v16 7/7] qcom-tgu: Add reset node to initialize

On 30/07/2026 09:07, 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@oss.qualcomm.com Reviewed-by: Jie Gan jie.gan@oss.qualcomm.com

---

.../ABI/testing/sysfs-bus-amba-devices-tgu | 7 ++ drivers/hwtracing/qcom/tgu.c | 84 +++++++++++++++++++ 2 files changed, 91 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu b/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu index a0cad2f16310..5c928a5fa033 100644 --- a/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu +++ b/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu @@ -51,3 +51,10 @@ KernelVersion: 7.2 Contact: Jinlong Mao jinlong.mao@oss.qualcomm.com, Songwei Chai songwei.chai@oss.qualcomm.com Description: (RW) Set/Get the counter value with specific step for TGU.

+What: /sys/bus/amba/devices/<tgu-name>/reset_tgu +Date: August 2026 +KernelVersion: 7.2 +Contact: Jinlong Mao jinlong.mao@oss.qualcomm.com, Songwei Chai songwei.chai@oss.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 ea83273a628c..d65a68faa741 100644 --- a/drivers/hwtracing/qcom/tgu.c +++ b/drivers/hwtracing/qcom/tgu.c @@ -228,6 +228,18 @@ static ssize_t tgu_write_all_hw_regs(struct tgu_drvdata *drvdata) int i, j, k, index = 0; TGU_UNLOCK(drvdata->base);

• /*

• * Quiesce the detection engine before mutating any comparison input.
  

• * This function is also reached from reset_tgu_store() while the TGU is
  

• * already running (TGU_CONTROL == 1); rewriting the priority/condition/
  

• * timer/counter registers register-by-register on a live engine could
  

• * feed a transient, half-updated match into CTI/interrupt consumers.
  

• * Programming with CONTROL == 0 and only re-enabling at the end keeps the
  

• * program-then-enable ordering for every caller.
  

• */
  

• writel(0, drvdata->base + TGU_CONTROL);
• for (i = 0; i < drvdata->num_step; i++) { for (j = 0; j < MAX_PRIORITY; j++) { for (k = 0; k < drvdata->num_reg; k++) {

@@ -459,8 +471,80 @@ static ssize_t enable_tgu_store(struct device *dev, } static DEVICE_ATTR_RW(enable_tgu); +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);
• struct value_table *vt = drvdata->value_table;
• unsigned long value;
• int i, j, ret;
• if (kstrtoul(buf, 0, &value) || value != 1)

• return -EINVAL;
  

• /*

• * Hold the mutex across the whole sequence so it cannot race with
  

• * enable_tgu_store()/tgu_dataset_store(): the enabled check and the
  

• * hardware access stay consistent. No PM reference is taken or dropped
  

• * here - the shadow tables are plain memory, and the hardware is only
  

• * touched when the device is already resumed via the enable reference.
  

• */
  

• guard(mutex)(&drvdata->lock);
• if (vt->priority) {

• size_t bytes = MAX_PRIORITY * drvdata->num_step *
  

• 		drvdata->num_reg * sizeof(unsigned int);
  

Please could you add a macro to compute "number" of each array ? Something like :

#define TGU_PRIORITY_SIZE(drvdata) (MAX_PRIORITY * (drvdata)->num_step * (drvdata)->num_reg)

So that we use the same size calculation for allocation and reset ? You may scale it by sizeof(*vt->priority)

• memset(vt->priority, 0, bytes);
  

• }
• if (vt->condition_decode) {

• size_t bytes = drvdata->num_condition_decode *
  

• 	       drvdata->num_step * sizeof(unsigned int);
  

Same as above

• memset(vt->condition_decode, 0, bytes);
  

• /* Initialize all condition decode registers to NOT (0x1000000) */
  

then why do the memset above ?

• for (i = 0; i < drvdata->num_step; i++)
  

• 	for (j = 0; j < drvdata->num_condition_decode; j++)
  

• 		vt->condition_decode[calculate_array_location(
  

• 			drvdata, i, TGU_CONDITION_DECODE, j)] =
  

• 			TGU_CONDITION_DECODE_NOT;
  

Then, we could simplify the above to:

for (i = 0; i < TGU_CONDITION_DECODE(drvdata); i++) vt->condition_decode[i] = TGU_CONDITION_DECODE_NOT;

Same for everything below.

Suzuki

• }
• if (vt->condition_select) {

• size_t bytes = drvdata->num_condition_select *
  

• 	       drvdata->num_step * sizeof(unsigned int);
  

• memset(vt->condition_select, 0, bytes);
  

• }
• if (vt->timer) {

• size_t bytes = drvdata->num_step * drvdata->num_timer *
  

• 		sizeof(unsigned int);
  

• memset(vt->timer, 0, bytes);
  

• }
• if (vt->counter) {

• size_t bytes = drvdata->num_step * drvdata->num_counter *
  

• 	       sizeof(unsigned int);
  

• memset(vt->counter, 0, bytes);
  

• }
• /* If the TGU is running, apply the cleared configuration immediately. */
• if (drvdata->enabled) {

• ret = tgu_write_all_hw_regs(drvdata);
  

• if (ret)
  

• 	return ret;
  

• }
• dev_dbg(dev, "Qualcomm-TGU reset complete\n");
• 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, };