Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Leonard Crestez <leonard.crestez@nxp.com>
To:     Anson Huang <anson.huang@nxp.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        Aisheng Dong <aisheng.dong@nxp.com>
CC:     "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH] firmware: imx: Skip return value check for some special
 SCU firmware APIs
Thread-Topic: [PATCH] firmware: imx: Skip return value check for some special
 SCU firmware APIs
Thread-Index: AQHVc4lSn4nBMGf230anvZh0PllY6g==
Date:   Wed, 25 Sep 2019 13:13:02 +0000
Message-ID: <VI1PR04MB70232DEA67972332611480CAEE870@VI1PR04MB7023.eurprd04.prod.outlook.com>
References: <1569406066-16626-1-git-send-email-Anson.Huang@nxp.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: nxp.com does not designate
 permitted sender hosts)
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 2526283c-1931-412f-009b-08d741ba18a9
X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Sep 2019 13:13:02.8264
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: I2ZvYu/9RCXozIhCIO+YRWSZ88ZLHxrJ/LeexbbRmitPfGQrW6/v1GrL7J6WOLK9uCykYC5EL0SfwG6XHwer8A==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1SPR01MB023
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 25.09.2019 13:09, Anson Huang wrote:=0A=
> The SCU firmware does NOT always have return value stored in message=0A=
> header's function element even the API has response data, those special=
=0A=
> APIs are defined as void function in SCU firmware, so they should be=0A=
> treated as return success always.=0A=
> =0A=
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>=0A=
> ---=0A=
> 	- This patch is based on the patch of https://eur01.safelinks.protection=
.outlook.com/?url=3Dhttps%3A%2F%2Fpatchwork.kernel.org%2Fpatch%2F11129553%2=
F&amp;data=3D02%7C01%7Cleonard.crestez%40nxp.com%7Cc0ced6cd07f04023977008d7=
41a07367%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637050029712216472&am=
p;sdata=3DCcq%2Fb2RJdMqmnL7VXrl8YhOlUwC7bWiUG%2BNmiw4OsSM%3D&amp;reserved=
=3D0=0A=
> ---=0A=
>   drivers/firmware/imx/imx-scu.c | 34 ++++++++++++++++++++++++++++++++--=
=0A=
>   1 file changed, 32 insertions(+), 2 deletions(-)=0A=
> =0A=
> diff --git a/drivers/firmware/imx/imx-scu.c b/drivers/firmware/imx/imx-sc=
u.c=0A=
> index 869be7a..ced5b12 100644=0A=
> --- a/drivers/firmware/imx/imx-scu.c=0A=
> +++ b/drivers/firmware/imx/imx-scu.c=0A=
> @@ -78,6 +78,11 @@ static int imx_sc_linux_errmap[IMX_SC_ERR_LAST] =3D {=
=0A=
>   	-EIO,	 /* IMX_SC_ERR_FAIL */=0A=
>   };=0A=
>   =0A=
> +static const struct imx_sc_rpc_msg whitelist[] =3D {=0A=
> +	{ .svc =3D IMX_SC_RPC_SVC_MISC, .func =3D IMX_SC_MISC_FUNC_UNIQUE_ID },=
=0A=
> +	{ .svc =3D IMX_SC_RPC_SVC_MISC, .func =3D IMX_SC_MISC_FUNC_GET_BUTTON_S=
TATUS },=0A=
> +};=0A=
=0A=
Until now this low level IPC code didn't treat any svc/func specially =0A=
and this seems good.=0A=
=0A=
The imx_scu_call_rpc function already has an have_resp argument and =0A=
callers are responsible to fill it. Can't we deal with this by adding an =
=0A=
additional err_ret flag passed by the caller?=0A=
=0A=
We can add wrapper functions to avoid tree-wide changes for all callers.=0A=
=0A=
> +=0A=
>   static struct imx_sc_ipc *imx_sc_ipc_handle;=0A=
>   =0A=
>   static inline int imx_sc_to_linux_errno(int errno)=0A=
> @@ -157,11 +162,24 @@ static int imx_scu_ipc_write(struct imx_sc_ipc *sc_=
ipc, void *msg)=0A=
>   	return 0;=0A=
>   }=0A=
>   =0A=
> +static bool imx_scu_call_skip_return_value_check(uint8_t svc, uint8_t fu=
nc)=0A=
> +{=0A=
> +	int i;=0A=
> +=0A=
> +	for (i =3D 0; i < ARRAY_SIZE(whitelist); i++)=0A=
> +		if (svc =3D=3D whitelist[i].svc &&=0A=
> +			func =3D=3D whitelist[i].func)=0A=
> +			return true;=0A=
> +=0A=
> +	return false;=0A=
> +}=0A=
> +=0A=
>   /*=0A=
>    * RPC command/response=0A=
>    */=0A=
>   int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_re=
sp)=0A=
>   {=0A=
> +	uint8_t saved_svc, saved_func;=0A=
>   	struct imx_sc_rpc_msg *hdr;=0A=
>   	int ret;=0A=
>   =0A=
> @@ -171,8 +189,11 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void=
 *msg, bool have_resp)=0A=
>   	mutex_lock(&sc_ipc->lock);=0A=
>   	reinit_completion(&sc_ipc->done);=0A=
>   =0A=
> -	if (have_resp)=0A=
> +	if (have_resp) {=0A=
>   		sc_ipc->msg =3D msg;=0A=
> +		saved_svc =3D ((struct imx_sc_rpc_msg *)msg)->svc;=0A=
> +		saved_func =3D ((struct imx_sc_rpc_msg *)msg)->func;=0A=
> +	}=0A=
>   	sc_ipc->count =3D 0;=0A=
>   	ret =3D imx_scu_ipc_write(sc_ipc, msg);=0A=
>   	if (ret < 0) {=0A=
> @@ -190,7 +211,16 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void=
 *msg, bool have_resp)=0A=
>   =0A=
>   		/* response status is stored in hdr->func field */=0A=
>   		hdr =3D msg;=0A=
> -		ret =3D hdr->func;=0A=
> +		/*=0A=
> +		 * Some special SCU firmware APIs do NOT have return value=0A=
> +		 * in hdr->func, but they do have response data, those special=0A=
> +		 * APIs are defined as void function in SCU firmware, so they=0A=
> +		 * should be treated as return success always.=0A=
> +		 */=0A=
> +		if (!imx_scu_call_skip_return_value_check(saved_svc, saved_func))=0A=
> +			ret =3D hdr->func;=0A=
> +		else=0A=
> +			ret =3D 0;=0A=
>   	}=0A=
>   =0A=
>   out:=0A=
> =0A=
=0A=