linux-kernel - Re: [PATCH v2 20/25] tty: serial: samsung_tty: Use devm_ioremap

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Date:   Sun, 21 Feb 2021 14:59:14 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Hector Martin <marcan@...can.st>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        Olof Johansson <olof@...om.net>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Tony Lindgren <tony@...mide.com>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Stan Skowronek <stan@...ellium.com>,
        Alexander Graf <graf@...zon.com>,
        Will Deacon <will@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 20/25] tty: serial: samsung_tty: Use devm_ioremap_resource

On Sun, 21 Feb 2021 14:38:16 +0000,
Hector Martin <marcan@...can.st> wrote:
> 
> On 21/02/2021 04.17, Marc Zyngier wrote:
> > On 2021-02-20 19:13, Krzysztof Kozlowski wrote:
> >> On Thu, Feb 18, 2021 at 11:01:21PM +0900, Hector Martin wrote:
> >>> On 16/02/2021 03.51, Krzysztof Kozlowski wrote:
> >>>>> Also fix a bug checking the return value, which should use IS_ERR().
> >>>> 
> >>>> No, no, no. We never, never combine fixing bugs with some rework.
> >>>> However devm_ioremap() returns NULL so where is the error?
> >>> 
> >>> Sorry, this was a commit message mistake. The code is correct and so
> >>> is the
> >>> patch: just the NULL check is correct for the previous variant and
> >>> IS_ERR is
> >>> correct for devm_ioremap_resource. I confused myself while writing the
> >>> commit message after the fact.
> >>> 
> >>>> Did you test your patches on existing platforms? If not, please mark all
> >>>> of them as RFT on next submission, so Greg does not pick them too fast.
> >>> 
> >>> I unfortunately don't have any Exynos devices where I could test the
> >>> code (I
> >>> have a couple but no serial connections, and I have no idea if mailine
> >>> would
> >>> run on them). I'll mark v3 as RFT.
> >> 
> >> If you have one of Odroid boards with Exynos, then you can nicely test
> >> Exynos. Others - depends, on board.
> >> Anyway I can test them for you. I just want to be sure that Greg waits
> >> for this testing.
> > 
> > Worse case, QEMU has some Exynos4210 emulation that is usable.
> 
> That's a good point; better than nothing, certainly.
> 
> Does anyone have a known good example of booting an exynos kernel
> under qemu? I tried building a plain 5.11 arm exynos_defconfig and
> booting it, but without much luck:
> 
> $ qemu-system-arm -kernel arch/arm/boot/zImage -append
> "console=ttySAC0,115200n8 debug" -dtb
> arch/arm/boot/dts/exynos4210-universal_c210.dtb -nographic -serial
> mon:stdio -M smdkc210 -smp 2

Here's what I've been using last time I had to muck with the 4210
stuff:

<quote>
qemu-system-arm \
	-kernel arch/arm/boot/zImage -M smdkc210 \
	-append "console=ttySAC0,115200n8 earlycon=smh root=/dev/mmcblk0p2 rootwait" \
	-nographic -semihosting -smp 2 \
	-dtb arch/arm/boot/dts/exynos4210-smdkv310.dtb \
	-drive if=sd,driver=null-co -drive if=sd,driver=null-co \
	-drive if=sd,file=../vminstall/bullseye32/MsiKFRxxujYIkiKT.img,format=raw
</quote>

where the last line points to a standard Debian image created
separately.

	M.

-- 
Without deviation from the norm, progress is not possible.