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From: Geert Uytterhoeven <>
To: Boris Brezillon <>
Cc: linux-m68k <>,
	David Woodhouse <>,
	Brian Norris <>,
	Marek Vasut <>,
	Richard Weinberger <>,
	MTD Maling List <>,
	Miquel Raynal <>,
	Linux Kernel Mailing List <>,
	Michael Schmitz <>
Subject: Re: [PATCH] m68k: Implement ndelay() as an inline function to force type checking/casting
Date: Mon, 14 May 2018 12:52:33 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Hi Boris,

On Mon, May 14, 2018 at 11:29 AM, Geert Uytterhoeven
<> wrote:
> On Sun, May 13, 2018 at 4:02 PM, Boris Brezillon
> <> wrote:
>> ndelay() is supposed to take an unsigned long, but if you define
>> ndelay() as a macro and the caller pass an unsigned long long instead
>> of an unsigned long, the unsigned long long to unsigned long cast is
>> not done and we end up with an "undefined reference to `__udivdi3'"
>> error at link time.
>> Fix that by making ndelay() an inline function and then defining dummy
>> ndelay() macro that redirects to the ndelay() function (it's how most
>> archs do to implement ndelay()).
>> Fixes: c8ee038bd148 ("m68k: Implement ndelay() based on the existing udelay() logic")
>> Signed-off-by: Boris Brezillon <>
>> ---
>> Hello Geert,
>> This patch is fixing the bug reported by kbuild test robot here [1].
>> I could have patched the PSEC_TO_NSEC() macro to cast the result of
>> the division on a u32, but I thought making m68k consistent with what
>> other archs do would be preferable.
>> Let me know if don't like the solution, and I'll patch the ndelay()
>> caller instead.
> Thanks for your patch!
> With the comment a few lines above removed:
>     - * This is a macro so that the const version can factor out the first
>     - * multiply and shift.
> Acked-by: Geert Uytterhoeven <>

I've just posted a fix for the root cause ("[PATCH] mtd: nand: Fix return
type of __DIVIDE() when called with 32-bit",, so the fix for m68k's ndelay() is not
that urgent anymore.

As your patch is still a valid fix, I'll apply it, and queue it up for v4.18.




Geert Uytterhoeven -- There's lots of Linux beyond ia32 --

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

      reply	other threads:[~2018-05-14 10:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-13 14:02 Boris Brezillon
2018-05-13 22:38 ` Andy Shevchenko
2018-05-14  7:23 ` Miquel Raynal
2018-05-14  9:29 ` Geert Uytterhoeven
2018-05-14 10:52   ` Geert Uytterhoeven [this message]

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