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

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Message-ID: <0393a600-609f-45de-96de-a0b0c5d7ac85@quicinc.com>
Date: Tue, 11 Jun 2024 18:25:12 +0530
From: Ekansh Gupta <quic_ekangupt@...cinc.com>
To: Dylan Van Assche <me@...anvanassche.be>,
        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>
CC: 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 5/24/2024 9:44 PM, 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>
> ---
Reviewed-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
>  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) {
> +		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;
>