linux-kernel - Re: [PATCH V2] firmware: imx: Skip return value check for some special SCU firmware APIs

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Message-ID: <20191009090043.4yq4l7iac3zgytnp@pengutronix.de>
Date:   Wed, 9 Oct 2019 11:00:43 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Anson Huang <Anson.Huang@....com>
Cc:     shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, aisheng.dong@....com, leonard.crestez@....com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Linux-imx@....com
Subject: Re: [PATCH V2] firmware: imx: Skip return value check for some
 special SCU firmware APIs

Hi Anson,

On 19-10-07 09:15, Anson Huang wrote:
> The SCU firmware does NOT always have return value stored in message
> header's function element even the API has response data, those special
> APIs are defined as void function in SCU firmware, so they should be
> treated as return success always.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> ---
> Changes since V1:
> 	- Use direct API check instead of calling another function to check.
> 	- This patch is based on https://patchwork.kernel.org/patch/11129553/
> ---
>  drivers/firmware/imx/imx-scu.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/imx/imx-scu.c b/drivers/firmware/imx/imx-scu.c
> index 869be7a..03b43b7 100644
> --- a/drivers/firmware/imx/imx-scu.c
> +++ b/drivers/firmware/imx/imx-scu.c
> @@ -162,6 +162,7 @@ static int imx_scu_ipc_write(struct imx_sc_ipc *sc_ipc, void *msg)
>   */
>  int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
>  {
> +	uint8_t saved_svc, saved_func;
>  	struct imx_sc_rpc_msg *hdr;
>  	int ret;
>  
> @@ -171,8 +172,11 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
>  	mutex_lock(&sc_ipc->lock);
>  	reinit_completion(&sc_ipc->done);
>  
> -	if (have_resp)
> +	if (have_resp) {
>  		sc_ipc->msg = msg;
> +		saved_svc = ((struct imx_sc_rpc_msg *)msg)->svc;

Why do we need to check the svc too?

> +		saved_func = ((struct imx_sc_rpc_msg *)msg)->func;

Nitpick, should we call it requested_func/req_func?

Regards,
  Marco

> +	}
>  	sc_ipc->count = 0;
>  	ret = imx_scu_ipc_write(sc_ipc, msg);
>  	if (ret < 0) {
> @@ -191,6 +195,16 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
>  		/* response status is stored in hdr->func field */
>  		hdr = msg;
>  		ret = hdr->func;
> +		/*
> +		 * Some special SCU firmware APIs do NOT have return value
> +		 * in hdr->func, but they do have response data, those special
> +		 * APIs are defined as void function in SCU firmware, so they
> +		 * should be treated as return success always.
> +		 */
> +		if ((saved_svc == IMX_SC_RPC_SVC_MISC) &&
> +			(saved_func == IMX_SC_MISC_FUNC_UNIQUE_ID ||
> +			 saved_func == IMX_SC_MISC_FUNC_GET_BUTTON_STATUS))
> +			ret = 0;
>  	}
>  
>  out:
> -- 
> 2.7.4
> 
> 
> 

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