Re: [PATCH] Revert "tty: serial: samsung_tty: build it for any platform" - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jiri Slaby <jslaby@suse.com>, Kukjin Kim <kgene@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH] Revert "tty: serial: samsung_tty: build it for any platform"
Date: Fri, 6 Mar 2020 13:32:27 +0100	[thread overview]
Message-ID: <20200306123227.GA3689963@kroah.com> (raw)
In-Reply-To: <20200306103652.GA3634389@kroah.com>

On Fri, Mar 06, 2020 at 11:36:52AM +0100, Greg Kroah-Hartman wrote:
> On Fri, Mar 06, 2020 at 11:23:01AM +0100, Geert Uytterhoeven wrote:
> > This reverts commit 175b558d0efb8b4f33aa7bd2c1b5389b912d3019.
> > 
> > When the user configures a kernel without support for Samsung SoCs, it
> > makes no sense to ask the user about enabling "Samsung SoC serial
> > support", as Samsung serial ports can only be found on Samsung SoCs.
> > 
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> >  drivers/tty/serial/Kconfig | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index 880b962015302dca..932ad51099deae7d 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -237,6 +237,7 @@ config SERIAL_CLPS711X_CONSOLE
> >  
> >  config SERIAL_SAMSUNG
> >  	tristate "Samsung SoC serial support"
> > +	depends on PLAT_SAMSUNG || ARCH_EXYNOS || COMPILE_TEST
> >  	select SERIAL_CORE
> >  	help
> >  	  Support for the on-chip UARTs on the Samsung S3C24XX series CPUs,
> 
> {sigh}
> 
> No, I don't want this.  My "goal" is to be able to get rid of all of the
> crazy "PLAT_*" symbols as they make it impossible to build a single
> kernel that supports multiple ARM64 systems.
> 
> As an example of just such a system, see the 5.4 tree here:
> 	https://android.googlesource.com/kernel/common/+/refs/heads/android-5.4
> it is now building and booting on multiple SoCs.
> 
> But yes, it still does have to enable some PLAT_* config options, but
> the goal is to not have to do that eventually.
> 
> There is no reason that we need vendor-specific config options just to
> lump random drivers into, like serial drivers.  If the hardware is not
> present, the driver will just not bind to the hardware, and all is fine.
> 
> Just like x86, we don't have this issue there, and ARM64 should also not
> have this.
> 
> Sorry for delay in writing this back to the original thread where you
> objected to the original patch, it's still in my review queue along with
> a ton of other serial patches.

Here's another good example of this happening, it's not just me working
toward this goal:
	https://lore.kernel.org/lkml/20200305103228.9686-2-zhang.lyra@gmail.com/