Re: [PATCH 1/2] arm64: change ARCH_SPRD Kconfig to tristate

From: Orson Zhai <orsonzhai@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Android Kernel Team <kernel-team@android.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Chunyan Zhang <zhang.lyra@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Chunyan Zhang <chunyan.zhang@unisoc.com>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	Jiri Slaby <jslaby@suse.com>,
	Baolin Wang <baolin.wang7@gmail.com>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/2] arm64: change ARCH_SPRD Kconfig to tristate
Date: Tue, 10 Mar 2020 18:13:51 +0800	[thread overview]
Message-ID: <CA+H2tpFaEp0Wbna=Z-A0bnno5hymVrSDE-397-Jdp6Uqsm0+qQ@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdUKD5Ob_o4E3bH9wx=6r2PU+7U3RQ_GVRj7ZQc-e5Y4TA@mail.gmail.com>

On Tue, Mar 10, 2020 at 5:52 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Orson,
>
> On Tue, Mar 10, 2020 at 10:41 AM Orson Zhai <orsonzhai@gmail.com> wrote:
> > On Mon, Mar 9, 2020 at 6:32 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Mon, Mar 9, 2020 at 9:32 AM Chunyan Zhang <zhang.lyra@gmail.com> wrote:
> > > > On Mon, 9 Mar 2020 at 16:03, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > > On Thu, Mar 5, 2020 at 11:33 AM Chunyan Zhang <zhang.lyra@gmail.com> wrote:
> > > > > > From: Chunyan Zhang <chunyan.zhang@unisoc.com>
> > > > > >
> > > > > > The default value of Kconfig for almost all sprd drivers are the same with
> > > > > > ARCH_SPRD, making these drivers built as modules as default would be easier
> > > > > > if we can set ARCH_SPRD as 'm', so this patch change ARCH_SPRD to tristate.
> > > > > >
> > > > > > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> > > > >
> > > > > Can you actually boot a kernel on a Spreadtrum platform when all platform
> > > > > and driver support is modular?
> > > >
> > > > Yes, even if all drivers are modular.
> > >
> > > Cool. No hard dependencies on e.g. regulators that are turned off when
> > > unused?
> > >
> > > > But I hope serial can be builtin, then I can have a console to see
> > > > kernel output before loading modules.
> > >
> > > No dependency on the clock driver?
> > > Oh, I see you have a hack in the serial driver, to assume default
> > > values when the serial port's parent clock is not found.  That may
> > > limit use of the other serial ports, depending on the actual serial
> > > hardware.
> >
> > There is an function named "sprd_uart_is_console()" in the driver
> > code. So the hack could be only applied when the
> > port is identified as console. And other ports might return
> > PROBE_DEFER until the clock is ready.
> >
> > Could it work out of the limitation?
>
> Yes, that could work.  You also have only a single SPRD_DEFAULT_SOURCE_CLK,
> which makes it simple to handle.
> For other SoCs, there may be a variation of possible values, depending on
> SoC and/or board.

Ok, thanks.

-Orson

>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

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