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

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Date:   Sun, 21 Feb 2021 23:38:16 +0900
From:   Hector Martin <marcan@...can.st>
To:     Marc Zyngier <maz@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Cc:     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 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

(I also tried without the -dtb option, in case qemu provides something 
usable)

Of course I'll still mark v3 as RFT, I just thought I might as well try 
qemu.

-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub