linux-kernel - Re: [PATCH v2 04/13] mailbox: pcc: Return early if no GAS register from pcc_mbox_cmd_complete

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Message-ID: <8ba294b7-e626-4ea3-af9a-48081f984f17@amperemail.onmicrosoft.com>
Date: Wed, 12 Mar 2025 18:27:16 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: Sudeep Holla <sudeep.holla@....com>, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Jassi Brar <jassisinghbrar@...il.com>, Huisong Li <lihuisong@...wei.com>,
 Adam Young <admiyo@...amperecomputing.com>,
 Robbie King <robbiek@...ghtlabs.com>
Subject: Re: [PATCH v2 04/13] mailbox: pcc: Return early if no GAS register
 from pcc_mbox_cmd_complete_check


On 3/5/25 11:38, Sudeep Holla wrote:
> pcc_mbox_cmd_complete_check() accesses pchan->cmd_complete.gas to check
> command completion status. Even if GAS is NULL, pcc_chan_reg_read() gets
> called which returns success doing nothing and then we return.
>
> Add an early return if pchan->cmd_complete.gas == NULL before performing
> any operations.
>
> Acked-by: Huisong Li <lihuisong@...wei.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/mailbox/pcc.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 42dd405482e407cf90e66917a46fb8e350e0eeaf..5a9ae67f5c50a3e43d30aa368c31c80b81db01f7 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -245,13 +245,13 @@ static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
>   	u64 val;
>   	int ret;
>   
> +	if (!pchan->cmd_complete.gas)
> +		return true;
> +
>   	ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
>   	if (ret)
>   		return false;
>   
> -	if (!pchan->cmd_complete.gas)
> -		return true;
> -
>   	/*
>   	 * Judge if the channel respond the interrupt based on the value of
>   	 * command complete.
>
tested-by: admiyo@...amperecomputing.com