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

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Date:   Thu, 26 Sep 2019 09:59:14 +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] firmware: imx: Skip return value check for some special
 SCU firmware APIs

Hi,

On 19-09-25 18:07, 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>
> ---
> 	- This patch is based on the patch of https://patchwork.kernel.org/patch/11129553/
> ---
>  drivers/firmware/imx/imx-scu.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/imx/imx-scu.c b/drivers/firmware/imx/imx-scu.c
> index 869be7a..ced5b12 100644
> --- a/drivers/firmware/imx/imx-scu.c
> +++ b/drivers/firmware/imx/imx-scu.c
> @@ -78,6 +78,11 @@ static int imx_sc_linux_errmap[IMX_SC_ERR_LAST] = {
>  	-EIO,	 /* IMX_SC_ERR_FAIL */
>  };
>  
> +static const struct imx_sc_rpc_msg whitelist[] = {
> +	{ .svc = IMX_SC_RPC_SVC_MISC, .func = IMX_SC_MISC_FUNC_UNIQUE_ID },
> +	{ .svc = IMX_SC_RPC_SVC_MISC, .func = IMX_SC_MISC_FUNC_GET_BUTTON_STATUS },
> +};

Is this going to be extended in the near future? I see some upcoming
problems here if someone uses a different scu-fw<->kernel combination as
nxp would suggest.

Regards,
  Marco

> +
>  static struct imx_sc_ipc *imx_sc_ipc_handle;
>  
>  static inline int imx_sc_to_linux_errno(int errno)
> @@ -157,11 +162,24 @@ static int imx_scu_ipc_write(struct imx_sc_ipc *sc_ipc, void *msg)
>  	return 0;
>  }
>  
> +static bool imx_scu_call_skip_return_value_check(uint8_t svc, uint8_t func)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(whitelist); i++)
> +		if (svc == whitelist[i].svc &&
> +			func == whitelist[i].func)
> +			return true;
> +
> +	return false;
> +}
> +
>  /*
>   * RPC command/response
>   */
>  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 +189,11 @@ 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;
> +		saved_func = ((struct imx_sc_rpc_msg *)msg)->func;
> +	}
>  	sc_ipc->count = 0;
>  	ret = imx_scu_ipc_write(sc_ipc, msg);
>  	if (ret < 0) {
> @@ -190,7 +211,16 @@ 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 (!imx_scu_call_skip_return_value_check(saved_svc, saved_func))
> +			ret = hdr->func;
> +		else
> +			ret = 0;
>  	}
>  
>  out:
> -- 
> 2.7.4
> 
> 
> 

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