linux-kernel - Re: [PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to the DSP

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Message-ID: <6fd44dd0-db11-6592-6670-2364af6ffdc6@linaro.org>
Date:   Sat, 6 May 2023 18:27:51 +0100
From:   Caleb Connolly <caleb.connolly@...aro.org>
To:     Dylan Van Assche <me@...anvanassche.be>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to
 the DSP



On 27/03/2023 19:42, 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>

Hi Dylan!

Personally pretty excited to LGTM. Please drop the noisy debug prints.
With those fixed

Reviewed-by: Caleb Connolly <caleb.connolly@...aro.org>
> ---
>  drivers/misc/fastrpc.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index f48466960f1b..caf2ae556956 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -2231,6 +2231,8 @@ 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);
> @@ -2274,6 +2276,20 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>  		}
>  	}
>  
> +	rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
> +	dev_info(rdev, "ASSIGNING MEMORY\n");

				^^
> +	if (domain_id == SDSP_DOMAIN_ID && rmem_node) {
> +		rmem = of_reserved_mem_lookup(rmem_node);
> +		if (!rmem)
> +			return -EINVAL;
> +
> +		dev_info(rdev, "ASSIGNING MEMORY START\n");

				^^
> +		qcom_scm_assign_mem(rmem->base, rmem->size, &data->perms,
> +				    data->vmperms, data->vmcount);
> +
> +		dev_info(rdev, "ASSIGNING MEMORY END\n");

				^^
> +	}
> +
>  	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
>  	data->secure = secure_dsp;
>  

-- 
Kind Regards,
Caleb (they/them)