linux-kernel - Re: [PATCH v4 2/2] firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt

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Message-ID: <e37cb2fc-14a3-b658-9df7-6f67a2c4d755@gmail.com>
Date:   Tue, 22 Dec 2020 19:37:22 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jim Quinlan <jim2101024@...il.com>,
        Sudeep Holla <sudeep.holla@....com>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com
Cc:     "open list:SYSTEM CONTROL & POWER/MANAGEMENT INTERFACE Mes..." 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] firmware: arm_scmi: Augment SMC/HVC to allow
 optional interrupt



On 12/22/2020 6:56 AM, Jim Quinlan wrote:
> The SMC/HVC SCMI transport is modified to allow the completion of an SCMI
> message to be indicated by an interrupt rather than the return of the smc
> call.  This accommodates the existing behavior of the BrcmSTB SCMI
> "platform" whose SW is already out in the field and cannot be changed.
> 
> Signed-off-by: Jim Quinlan <jim2101024@...il.com>

This looks good to me, just one question below:

[snip]

> @@ -111,6 +145,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
>  	shmem_tx_prepare(scmi_info->shmem, xfer);
>  
>  	arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
> +	if (scmi_info->irq)
> +		wait_for_completion(&scmi_info->tx_complete);

Do we need this to have a preceding call to reinit_completion()? It does
not look like this is going to make any practical difference but there
are drivers doing that for correctness.
-- 
Florian