linux-kernel - Re: [PATCH v5 1/2] misc: fastrpc: support complete DMA pool access to the DSP

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Message-ID: <vrw2v45cjem4qzhwtvapwzyjtq42dzkirkvxajgfd4retvmjyw@64fnc3ewjlnf>
Date: Tue, 11 Jun 2024 22:56:47 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Dylan Van Assche <me@...anvanassche.be>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
	Amol Maheshwari <amahesh@....qualcomm.com>, Arnd Bergmann <arnd@...db.de>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Caleb Connolly <caleb.connolly@...aro.org>, phone-devel@...r.kernel.org, 
	~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v5 1/2] misc: fastrpc: support complete DMA pool access
 to the DSP

On Fri, May 24, 2024 at 06:14:02PM +0200, Dylan Van Assche wrote:
> To support FastRPC Context Banks which aren't mapped via the SMMU,
> make the whole reserved memory region available to the DSP to allow
> access to coherent buffers.
> 
> This is performed by assigning the memory to the DSP via a hypervisor
> call to set the correct permissions for the Virtual Machines on the DSP.
> This is only necessary when a memory region is provided for SLPI DSPs
> so guard this with a domain ID check.
> 
> Signed-off-by: Dylan Van Assche <me@...anvanassche.be>
> Reviewed-by: Caleb Connolly <caleb.connolly@...aro.org>
> ---
>  drivers/misc/fastrpc.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 4c67e2c5a82e..c06667b29055 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -2255,6 +2255,8 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>  	int i, err, domain_id = -1, vmcount;
>  	const char *domain;
>  	bool secure_dsp;
> +	struct device_node *rmem_node;
> +	struct reserved_mem *rmem;
>  	unsigned int vmids[FASTRPC_MAX_VMIDS];
>  
>  	err = of_property_read_string(rdev->of_node, "label", &domain);
> @@ -2297,6 +2299,23 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>  		}
>  	}
>  
> +	rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
> +	if (domain_id == SDSP_DOMAIN_ID && rmem_node) {

I think we can drop the domain_id check here.

The rest looks good to me.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>


> +		u64 src_perms;
> +
> +		rmem = of_reserved_mem_lookup(rmem_node);
> +		if (!rmem) {
> +			err = -EINVAL;
> +			goto fdev_error;
> +		}
> +
> +		src_perms = BIT(QCOM_SCM_VMID_HLOS);
> +
> +		qcom_scm_assign_mem(rmem->base, rmem->size, &src_perms,
> +				    data->vmperms, data->vmcount);
> +
> +	}
> +
>  	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
>  	data->secure = secure_dsp;
>  
> -- 
> 2.45.1
> 

-- 
With best wishes
Dmitry