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From:   Leonard Crestez <leonard.crestez@nxp.com>
To:     Anson Huang <anson.huang@nxp.com>, Shawn Guo <shawnguo@kernel.org>
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Subject: Re: [PATCH 1/2] soc: imx-sc: add i.MX system controller soc driver
 support
Thread-Topic: [PATCH 1/2] soc: imx-sc: add i.MX system controller soc driver
 support
Thread-Index: AQHU8DKsAg9Kriz6B0mooDc33xId4w==
Date:   Mon, 22 Apr 2019 08:48:56 +0000
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On 4/22/2019 9:46 AM, Anson Huang wrote:=0A=
>> -----Original Message-----=0A=
>> From: Anson Huang=0A=
>>> From: Shawn Guo [mailto:shawnguo@kernel.org]=0A=
>>> On Sun, Apr 21, 2019 at 03:40:00PM +0800, Shawn Guo wrote:=0A=
>>>> On Thu, Apr 11, 2019 at 06:49:12AM +0000, Anson Huang wrote:=0A=
>>>>> i.MX8QXP is an ARMv8 SoC which has a Cortex-M4 system controller=0A=
>>>>> inside, the system controller is in charge of controlling power,=0A=
>>>>> clock and fuse etc..=0A=
>>>>>=0A=
>>>>> This patch adds i.MX system controller soc driver support, Linux=0A=
>>>>> kernel has to communicate with system controller via MU (message=0A=
>>>>> unit) IPC to get soc revision, uid etc..=0A=
>>>>>=0A=
>>>>> With this patch, soc info can be read from sysfs:=0A=
>>>>>=0A=
>>>>>   drivers/soc/imx/Kconfig      |   7 ++=0A=
>>>>>   drivers/soc/imx/Makefile     |   1 +=0A=
>>>>>   drivers/soc/imx/soc-imx-sc.c | 220=0A=
>>>>> +++++++++++++++++++++++++++++++++++++++++++=0A=
>>>>>   3 files changed, 228 insertions(+)  create mode 100644=0A=
>>>>> drivers/soc/imx/soc-imx-sc.c=0A=
>>>>=0A=
>>>> Rather than creating a new driver, please take a look at Abel's=0A=
>>>> generic=0A=
>>>> i.MX8 SoC driver, and see if it can be extended to cover i.MX8QXP.=0A=
>>=0A=
>> Got it, I didn't notice that this patch bas been accepted, I will redo t=
he patch=0A=
>> based on it, thanks.=0A=
> =0A=
> I have sent the new patch set to support i.MX8QXP SoC revision based on g=
eneric i.MX8=0A=
> SoC driver, however, the Kconfig modification is NOT good, it may break i=
.MX8MQ if IMX_SCU=0A=
> is NOT enabled, although we can add some warp function for SCU firmware A=
PI call to fix it,=0A=
> but after further thought and discussion with Dong Aisheng, I think we ma=
y need to roll back to=0A=
> use this patch series to create a new SoC driver dedicated for i.MX8 SoCs=
=0A=
> with system controller inside, such as i.MX8QXP, i.MX8QM etc., the reason=
 are as below:=0A=
> =0A=
> For i.MX8MQ/i.MX8MM:=0A=
> 	1. SoC driver does NOT depends on i.MX SCU firmware, so no need to use p=
latform driver=0A=
> 	     probe model, just device_init phase call is good enough;=0A=
> 	2. The SoC driver no need to depends on IMX_SCU, so it can be always bui=
lt in, no need to=0A=
> 	     check IMX_SCU config;=0A=
> 	3. The fuse check for CPU speed grading, HDCP status, NoC settings etc. =
could be added to this driver,=0A=
> 	    but they are ONLY for i.MX8MQ/i.MX8MM etc..=0A=
> For i.MX8QXP/i.MX8QM:=0A=
> 	1. SoC driver MUST depends on IMX_SCU;=0A=
> 	2. MUST use platform model to support defer probe;=0A=
> 	3. No fuse check for CPU speed grading.=0A=
> =0A=
> So, I guess the reused code for i.MX8MQ and i.MX8QXP is ONLY those part o=
f creating SoC id device node (less than=0A=
> 30% I think), all other functions are implemented in total different ways=
, that is why I created the imx_sc_soc driver=0A=
> in this patch series, so do you think we can add new SoC driver for i.MX8=
 SoC with SCU inside? Putting 2 different architecture=0A=
> SoCs' driver into 1 file looks like NOT making enough sense.=0A=
=0A=
+1 for separate SOC driver. The 8mq/8mm and 8qm/8qxp families are very =0A=
different, they just happen to share the imx8 prefix.=0A=
=0A=
It makes sense to allow people to compile one without the other and this =
=0A=
is easier with distinct SOC drivers.=0A=
=0A=
--=0A=
Regards,=0A=
Leonard=0A=