Re: [PATCH v5 04/12] coresight: etm4x: exclude ss_status from drvdata->config

[Leo Yan]

On Wed, Apr 15, 2026 at 05:55:20PM +0100, Yeoreum Yun wrote:

[...]

> @@ -573,11 +573,9 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>  		etm4x_relaxed_write32(csa, config->res_ctrl[i], TRCRSCTLRn(i));
>  
>  	for (i = 0; i < caps->nr_ss_cmp; i++) {
> -		/* always clear status bit on restart if using single-shot */
> -		if (config->ss_ctrl[i] || config->ss_pe_cmp[i])
> -			config->ss_status[i] &= ~TRCSSCSRn_STATUS;
>  		etm4x_relaxed_write32(csa, config->ss_ctrl[i], TRCSSCCRn(i));
> -		etm4x_relaxed_write32(csa, config->ss_status[i], TRCSSCSRn(i));
> +		/* always clear status and pending bits on restart if using single-shot */
> +		etm4x_relaxed_write32(csa, 0x0, TRCSSCSRn(i));

In Arm ARM, D24.4.60 TRCSSCSR<n>, bits[0..3] are RO.  I think it is
fine for directly clear the regiser with zero (means it will only
clear status / pending bits).

[...]

> @@ -1841,10 +1839,11 @@ static ssize_t sshot_status_show(struct device *dev,
>  {
>  	unsigned long val;
>  	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +	const struct etmv4_caps *caps = &drvdata->caps;
>  	struct etmv4_config *config = &drvdata->config;
>  
>  	raw_spin_lock(&drvdata->spinlock);
> -	val = config->ss_status[config->ss_idx];
> +	val = caps->ss_cmp[config->ss_idx];
>  	raw_spin_unlock(&drvdata->spinlock);
>  	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>  }

This sysfs knob never can print out a realtime status for sshot, I am
fine for only printing caps->ss_cmp, this can avoid any misleading.

@Suzuki, @Mike, do you agree with the change above?

If maintainers agree with this, as Jie suggested, it is good to add a
comment in the code and update the document:

  Documentation/trace/coresight/coresight-etm4x-reference.rst

Thanks,
Leo