linux-kernel - Re: [PATCH v3] coresight: etm4x: Handle accesses to TRCSTALLCTLR

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Message-ID: <20210127190045.GA1165637@xps15>
Date:   Wed, 27 Jan 2021 12:00:45 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        coresight@...ts.linaro.org, anshuman.khandual@....com,
        stable@...r.kernel.org, Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>
Subject: Re: [PATCH v3] coresight: etm4x: Handle accesses to TRCSTALLCTLR

On Wed, Jan 27, 2021 at 06:46:17PM +0000, Suzuki K Poulose wrote:
> TRCSTALLCTLR register is only implemented if
> 
>    TRCIDR3.STALLCTL == 0b1
> 
> Make sure the driver touches the register only it is implemented.
> 
> Cc: stable@...r.kernel.org
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: Leo Yan <leo.yan@...aro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
> Changes since v2:
>  - Ignore STALLCTL for sysfs mode
> ---
>  drivers/hwtracing/coresight/coresight-etm4x-core.c  | 9 ++++++---
>  drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 2 +-
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 473ab7480a36..5017d33ba4f5 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -306,7 +306,8 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>  	etm4x_relaxed_write32(csa, 0x0, TRCAUXCTLR);
>  	etm4x_relaxed_write32(csa, config->eventctrl0, TRCEVENTCTL0R);
>  	etm4x_relaxed_write32(csa, config->eventctrl1, TRCEVENTCTL1R);
> -	etm4x_relaxed_write32(csa, config->stall_ctrl, TRCSTALLCTLR);
> +	if (drvdata->stallctl)
> +		etm4x_relaxed_write32(csa, config->stall_ctrl, TRCSTALLCTLR);
>  	etm4x_relaxed_write32(csa, config->ts_ctrl, TRCTSCTLR);
>  	etm4x_relaxed_write32(csa, config->syncfreq, TRCSYNCPR);
>  	etm4x_relaxed_write32(csa, config->ccctlr, TRCCCCTLR);
> @@ -1463,7 +1464,8 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
>  	state->trcauxctlr = etm4x_read32(csa, TRCAUXCTLR);
>  	state->trceventctl0r = etm4x_read32(csa, TRCEVENTCTL0R);
>  	state->trceventctl1r = etm4x_read32(csa, TRCEVENTCTL1R);
> -	state->trcstallctlr = etm4x_read32(csa, TRCSTALLCTLR);
> +	if (drvdata->stallctl)
> +		state->trcstallctlr = etm4x_read32(csa, TRCSTALLCTLR);
>  	state->trctsctlr = etm4x_read32(csa, TRCTSCTLR);
>  	state->trcsyncpr = etm4x_read32(csa, TRCSYNCPR);
>  	state->trcccctlr = etm4x_read32(csa, TRCCCCTLR);
> @@ -1575,7 +1577,8 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>  	etm4x_relaxed_write32(csa, state->trcauxctlr, TRCAUXCTLR);
>  	etm4x_relaxed_write32(csa, state->trceventctl0r, TRCEVENTCTL0R);
>  	etm4x_relaxed_write32(csa, state->trceventctl1r, TRCEVENTCTL1R);
> -	etm4x_relaxed_write32(csa, state->trcstallctlr, TRCSTALLCTLR);
> +	if (drvdata->stallctl)
> +		etm4x_relaxed_write32(csa, state->trcstallctlr, TRCSTALLCTLR);
>  	etm4x_relaxed_write32(csa, state->trctsctlr, TRCTSCTLR);
>  	etm4x_relaxed_write32(csa, state->trcsyncpr, TRCSYNCPR);
>  	etm4x_relaxed_write32(csa, state->trcccctlr, TRCCCCTLR);
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index b646d53a3133..0995a10790f4 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -389,7 +389,7 @@ static ssize_t mode_store(struct device *dev,
>  		config->eventctrl1 &= ~BIT(12);
>  
>  	/* bit[8], Instruction stall bit */
> -	if (config->mode & ETM_MODE_ISTALL_EN)
> +	if ((config->mode & ETM_MODE_ISTALL_EN) && (drvdata->stallctl == true))

I have applied this patch.

>  		config->stall_ctrl |= BIT(8);
>  	else
>  		config->stall_ctrl &= ~BIT(8);
> -- 
> 2.24.1
>