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Date:   Wed, 4 Mar 2020 10:40:05 +0000
From:   Sudeep Holla <sudeep.holla@arm.com>
To:     peng.fan@nxp.com
Cc:     robh+dt@kernel.org, viresh.kumar@linaro.org, f.fainelli@gmail.com,
        linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        Sudeep Holla <sudeep.holla@arm.com>
Subject: Re: [PATCH V4 2/2] firmware: arm_scmi: add smc/hvc transport
Message-ID: <20200304103954.GA25004@bogus>
References: <1583201219-15839-1-git-send-email-peng.fan@nxp.com>
 <1583201219-15839-3-git-send-email-peng.fan@nxp.com>
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On Tue, Mar 03, 2020 at 10:06:59AM +0800, peng.fan@nxp.com wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> Take arm,smc-id as the 1st arg, leave the other args as zero for now.
> There is no Rx, only Tx because of smc/hvc not support Rx.
>
> Signed-off-by: Peng Fan <peng.fan@nxp.com>

[...]

> +static int smc_send_message(struct scmi_chan_info *cinfo,
> +			    struct scmi_xfer *xfer)
> +{
> +	struct scmi_smc *scmi_info = cinfo->transport_info;
> +	struct arm_smccc_res res;
> +
> +	shmem_tx_prepare(scmi_info->shmem, xfer);

How do we protect another thread/process on another CPU going and
modifying the same shmem with another request ? We may need notion
of channel with associated shmem and it is protected with some lock.

--
Regards,
Sudeep