Re: [PATCH 4/4] firmware: qcom: scm: introduce qcom_scm_bw class for bandwidth management

[Mukesh Ojha]

On Wed, Jul 01, 2026 at 03:38:58PM +0200, Bartosz Golaszewski wrote:
> Define DEFINE_CLASS(qcom_scm_bw) that calls qcom_scm_bw_enable() on
> construction and automatically calls qcom_scm_bw_disable() at scope exit
> *if* the enable succeeded.
> 
> This allows us to convert all call sites to using
> CLASS(qcom_scm_bw, bw)() instead of the manual enable/check/disable
> pattern and to remove the associated goto labels in cleanup path.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 61 ++++++++++++++++------------------------
>  1 file changed, 25 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 35aa9e8886b6ce8ab8eaf16c83fef7aafaef2822..6b64ed5a2b70a5ad3e57efb780df7dfa43518f91 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -227,6 +227,9 @@ static void qcom_scm_bw_disable(void)
>  	mutex_unlock(&__scm->scm_bw_lock);
>  }
>  
> +DEFINE_CLASS(qcom_scm_bw, int, if (!_T) qcom_scm_bw_disable(),
> +	     qcom_scm_bw_enable(), void)
> +
>  enum qcom_scm_convention qcom_scm_convention = SMC_CONVENTION_UNKNOWN;
>  static DEFINE_SPINLOCK(scm_query_lock);
>  
> @@ -621,14 +624,13 @@ static int __qcom_scm_pas_init_image(u32 pas_id, dma_addr_t mdata_phys,
>  	if (clk)
>  		return clk;
>  
> -	ret = qcom_scm_bw_enable();
> -	if (ret)
> -		return ret;
> +	CLASS(qcom_scm_bw, bw)();
> +	if (bw)
> +		return bw;
>  
>  	desc.args[1] = mdata_phys;
>  
>  	ret = qcom_scm_call(__scm->dev, &desc, res);
> -	qcom_scm_bw_disable();
>  
>  	return ret;
>  }
> @@ -760,12 +762,11 @@ int qcom_scm_pas_mem_setup(u32 pas_id, phys_addr_t addr, phys_addr_t size)
>  	if (clk)
>  		return clk;
>  
> -	ret = qcom_scm_bw_enable();
> -	if (ret)
> -		return ret;
> +	CLASS(qcom_scm_bw, bw)();
> +	if (bw)
> +		return bw;
>  
>  	ret = qcom_scm_call(__scm->dev, &desc, &res);
> -	qcom_scm_bw_disable();
>  
>  	return ret ? : res.result[0];
>  }
> @@ -870,15 +871,14 @@ struct resource_table *qcom_scm_pas_get_rsc_table(struct qcom_scm_pas_context *c
>  	struct resource_table empty_rsc = {};
>  	size_t size = SZ_16K;
>  	void *tbl_ptr;
> -	int ret;
>  
>  	CLASS(qcom_scm_clk, clk)();
>  	if (clk)
>  		return ERR_PTR(clk);
>  
> -	ret = qcom_scm_bw_enable();
> -	if (ret)
> -		return ERR_PTR(ret);
> +	CLASS(qcom_scm_bw, bw)();
> +	if (bw)
> +		return ERR_PTR(bw);
>  
>  	/*
>  	 * TrustZone can not accept buffer as NULL value as argument hence,
> @@ -893,10 +893,8 @@ struct resource_table *qcom_scm_pas_get_rsc_table(struct qcom_scm_pas_context *c
>  	void *input_rt_tzm __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
>  								  input_rt_size,
>  								  GFP_KERNEL);
> -	if (!input_rt_tzm) {
> -		ret = -ENOMEM;
> -		goto disable_scm_bw;
> -	}
> +	if (!input_rt_tzm)
> +		return ERR_PTR(-ENOMEM);
>  
>  	memcpy(input_rt_tzm, input_rt, input_rt_size);
>  
> @@ -909,23 +907,16 @@ struct resource_table *qcom_scm_pas_get_rsc_table(struct qcom_scm_pas_context *c
>  							     input_rt_tzm,
>  							     input_rt_size,
>  							     &size);
> -	if (IS_ERR(output_rt_tzm)) {
> -		ret = PTR_ERR(output_rt_tzm);
> -		goto disable_scm_bw;
> -	}
> +	if (IS_ERR(output_rt_tzm))
> +		return output_rt_tzm;
>  
>  	tbl_ptr = kmemdup(output_rt_tzm, size, GFP_KERNEL);
> -	if (!tbl_ptr) {
> -		ret = -ENOMEM;
> -		goto disable_scm_bw;
> -	}
> +	if (!tbl_ptr)
> +		return ERR_PTR(-ENOMEM);
>  
>  	*output_rt_size = size;
>  
> -disable_scm_bw:
> -	qcom_scm_bw_disable();
> -
> -	return ret ? ERR_PTR(ret) : tbl_ptr;
> +	return tbl_ptr;
>  }
>  EXPORT_SYMBOL_GPL(qcom_scm_pas_get_rsc_table);
>  
> @@ -952,12 +943,11 @@ int qcom_scm_pas_auth_and_reset(u32 pas_id)
>  	if (clk)
>  		return clk;
>  
> -	ret = qcom_scm_bw_enable();
> -	if (ret)
> -		return ret;
> +	CLASS(qcom_scm_bw, bw)();
> +	if (bw)
> +		return bw;
>  
>  	ret = qcom_scm_call(__scm->dev, &desc, &res);
> -	qcom_scm_bw_disable();
>  
>  	return ret ? : res.result[0];
>  }
> @@ -1032,12 +1022,11 @@ int qcom_scm_pas_shutdown(u32 pas_id)
>  	if (clk)
>  		return clk;
>  
> -	ret = qcom_scm_bw_enable();
> -	if (ret)
> -		return ret;
> +	CLASS(qcom_scm_bw, bw)();
> +	if (bw)
> +		return bw;
>  
>  	ret = qcom_scm_call(__scm->dev, &desc, &res);
> -	qcom_scm_bw_disable();
>  
>  	return ret ? : res.result[0];
>  }

Reviewed-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>

-- 
-Mukesh Ojha