linux-kernel - Re: [PATCH 1/3] arm64: Remove CONFIG_SOC_IMX8MQ and use ARCH

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Date:   Fri, 14 Dec 2018 12:41:46 +0000
From:   Abel Vesa <abel.vesa@....com>
To:     Lucas Stach <l.stach@...gutronix.de>
CC:     Shawn Guo <shawnguo@...nel.org>, Stephen Boyd <sboyd@...nel.org>,
        Aisheng Dong <aisheng.dong@....com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Olof Johansson <olof@...om.net>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>, Rob Herring <robh@...nel.org>,
        Will Deacon <will.deacon@....com>,
        Fabio Estevam <fabio.estevam@....com>
Subject: Re: [PATCH 1/3] arm64: Remove CONFIG_SOC_IMX8MQ and use ARCH_MXC
 instead

On 18-12-14 10:22:11, Lucas Stach wrote:
> Hi Shawn,
> 
> Am Freitag, den 14.12.2018, 09:12 +0800 schrieb Shawn Guo:
> > On Thu, Dec 13, 2018 at 02:51:50PM +0000, Abel Vesa wrote:
> > ...
> > > > > diff --git a/arch/arm64/Kconfig.platforms
> > > > > b/arch/arm64/Kconfig.platforms
> > > > > index 7e1545a..318dbb9 100644
> > > > > --- a/arch/arm64/Kconfig.platforms
> > > > > +++ b/arch/arm64/Kconfig.platforms
> > > > > @@ -148,14 +148,6 @@ config ARCH_MXC
> > > > > > > > >  	  This enables support for the ARMv8 based SoCs in the
> > > > > > > > >  	  NXP i.MX family.
> > > > >  
> > > > > -config SOC_IMX8MQ
> > > > > > > > > -	bool "i.MX8MQ support"
> > > > > > > > > -	depends on ARCH_MXC
> > > > > > > > > -	select ARM64_ERRATUM_843419
> > > > > > > > > -	select ARM64_ERRATUM_845719
> > > > > > > > > -	help
> > > > > > > > > -	  This enables support for the i.MX8MQ SoC.
> > > > > -
> > > > 
> > > > NACK on this one. Having a single place where stuff that is absolutely
> > > > critical for proper SoC operation can be selected is very useful and
> > > > avoids hard to debug issues due to slightly wrong configs in the long
> > > > run.
> > > 
> > > As mentioned in the cover letter, please ignore this patch set entirely.
> > > The ARCH_MXC is actually used on arm32 too, so it won't work.
> > > 
> > > I'm working on a patchset that will add the Kconfig into 
> > > drivers/clk/imx/ and in it will add CLK_IMX8MQ. That will
> > > fix the clock dependency since the CLK_IMX8MQ will depend on
> > > ARCH_MXC and ARM64. I believe the CLK_IMX8QXP will follow
> > > the same pattern.
> > > 
> > > As for the SOC_IMX8MQ, all the other vendors have one single
> > > config for all the arm64 platforms. TBH, to control every SoC
> > > independently it's a little bit of an overkill.
> > 
> > Lucas,
> > 
> > We are still waiting for further comments from Olof [1].  But it sounds
> > like SoC specific option is not welcomed on ARM64.
> 
> While I personally would prefer to keep the SoC options, I see that we
> need to align with the judgment of the arm-soc maintainers.
> 
> But at the very least we should keep the select for vital system
> workarounds. They need to move to the arch Kconfig symbol in that case
> and might select stuff that isn't needed on each of the i.MX8 SoCs. But
> better enabling more workaround and drivers than necessary than having
> hard to debug system failures in the future.
> 

I get your point. But that seems to be an issue with the whole arm64 approach.
TBH, I believe now would be the perfect time to "get it right" on IMX since the 8MQ
is the first one to get boot-up support upstream. It will be way much harder
to change this later when more arm64 IMX SoCs get upstreamed.

I would really love more opinions on this.

I have patches on stand-by that remove the SOC_IMX8MQ in all the subsystems and
a patch for the defconfig update which I'll keep on holding on to until there
is a agreement on this.

> Regards,
> Lucas