linux-kernel - Re: [PATCH v3 1/9] soc: qcom: cpr3: Fix 'acc

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Message-ID: <jgboqj56nfeuv7qmi34chan46u5urdxyezqhfmqdq3clvcv2k6@k7aktead5qbk>
Date: Wed, 26 Jun 2024 21:21:43 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Varadarajan Narayanan <quic_varada@...cinc.com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	angelogioacchino.delregno@...labora.com, andersson@...nel.org, konrad.dybcio@...aro.org, 
	mturquette@...libre.com, sboyd@...nel.org, ilia.lin@...nel.org, rafael@...nel.org, 
	viresh.kumar@...aro.org, ulf.hansson@...aro.org, quic_sibis@...cinc.com, 
	otto.pflueger@...cue.de, neil.armstrong@...aro.org, luca@...tu.xyz, abel.vesa@...aro.org, 
	danila@...xyga.com, quic_ipkumar@...cinc.com, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 1/9] soc: qcom: cpr3: Fix 'acc_desc' usage

On Wed, Jun 26, 2024 at 04:09:54PM GMT, Varadarajan Narayanan wrote:
> cpr3 code assumes that 'acc_desc' is available for SoCs
> implementing CPR version 4 or less. However, IPQ9574 SoC
> implements CPRv4 without ACC. This causes NULL pointer accesses
> resulting in crashes. Hence, check is 'acc_desc' is populated
> before using it.
> 
> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> ---
>  drivers/pmdomain/qcom/cpr3.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pmdomain/qcom/cpr3.c b/drivers/pmdomain/qcom/cpr3.c
> index c7790a71e74f..c28028be50d8 100644
> --- a/drivers/pmdomain/qcom/cpr3.c
> +++ b/drivers/pmdomain/qcom/cpr3.c
> @@ -2399,12 +2399,12 @@ static int cpr_pd_attach_dev(struct generic_pm_domain *domain,
>  		if (ret)
>  			goto exit;
>  
> -		if (acc_desc->config)
> +		if (acc_desc && acc_desc->config)
>  			regmap_multi_reg_write(drv->tcsr, acc_desc->config,
>  					       acc_desc->num_regs_per_fuse);
>  
>  		/* Enable ACC if required */
> -		if (acc_desc->enable_mask)
> +		if (acc_desc && acc_desc->enable_mask)
>  			regmap_update_bits(drv->tcsr, acc_desc->enable_reg,
>  					   acc_desc->enable_mask,
>  					   acc_desc->enable_mask);
> @@ -2676,7 +2676,7 @@ static int cpr_probe(struct platform_device *pdev)
>  	desc = data->cpr_desc;
>  
>  	/* CPRh disallows MEM-ACC access from the HLOS */
> -	if (!data->acc_desc && desc->cpr_type < CTRL_TYPE_CPRH)
> +	if (!data->acc_desc && desc->cpr_type < CTRL_TYPE_CPR4)
>  		return -EINVAL;
>  
>  	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
> @@ -2703,7 +2703,7 @@ static int cpr_probe(struct platform_device *pdev)
>  
>  	mutex_init(&drv->lock);
>  
> -	if (desc->cpr_type < CTRL_TYPE_CPRH) {
> +	if (desc->cpr_type < CTRL_TYPE_CPR4) {

This is incorrect. This disables ACC usage for CPR4, while GFX CPR on
MSM8998 (which is CPR4) seems to use ACC.

>  		np = of_parse_phandle(dev->of_node, "qcom,acc", 0);
>  		if (!np)
>  			return -ENODEV;
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry