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

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Date:   Wed, 9 Oct 2019 11:37:45 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Anson Huang <anson.huang@....com>
Cc:     "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        Aisheng Dong <aisheng.dong@....com>,
        Leonard Crestez <leonard.crestez@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH V2] firmware: imx: Skip return value check for some
 special SCU firmware APIs

Hi Anson,

On 19-10-09 09:09, Anson Huang wrote:
> Hi, Marco
> 
> > 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatc
> > >
> > hwork.kernel.org%2Fpatch%2F11129553%2F&amp;data=02%7C01%7Canson.
> > huang%
> > >
> > 40nxp.com%7Cbefd2849a124462caa4a08d74c972dc9%7C686ea1d3bc2b4c6f
> > a92cd99
> > >
> > c5c301635%7C0%7C0%7C637062084506889431&amp;sdata=7fW8hZB4AaUK
> > 9QTKTJQR7
> > > LuV2nGo6e%2Fqb%2Fqmn4ykquk%3D&amp;reserved=0
> > > ---
> > >  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?
> 
> It is because the SCU firmware API has many different category called SVC, each category has
> many different function, and the function value could be same in each category,
> for example, there are IRQ, PM, MISC etc. SVC category, and each of them could have function
> type defined as 0, 1, 2 .... That is why I need to save both SVC and FUNC to identify the SCU FW
> API. See below: 
> 
> PM SVC:
> #define PM_FUNC_SET_PARTITION_POWER_MODE 1U /* Index for pm_set_partition_power_mode() RPC call */
> #define PM_FUNC_GET_SYS_POWER_MODE 2U /* Index for pm_get_sys_power_mode() RPC call */
> #define PM_FUNC_SET_RESOURCE_POWER_MODE 3U /* Index for pm_set_resource_power_mode() RPC call */
> 
> MISC SVC:
> #define MISC_FUNC_SET_CONTROL 1U /* Index for misc_set_control() RPC call */
> #define MISC_FUNC_GET_CONTROL 2U /* Index for misc_get_control() RPC call */
> #define MISC_FUNC_SET_MAX_DMA_GROUP 4U /* Index for misc_set_max_dma_group() RPC call */

Ahh, okay get it. Thanks for the explanation.

> > 
> > > +		saved_func = ((struct imx_sc_rpc_msg *)msg)->func;
> > 
> > Nitpick, should we call it requested_func/req_func?
> 
> OK, I will change them If I have to sent out a new version, otherwise, I think the saved_func and saved_svc
> should also be fine.

Just a nitpick ;)

Feel free to add my

Reviewed-by: Marco Felsch <m.felsch@...gutronix.de>

Regards,
  Marco

> 
> Thanks,
> Anson

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