From: Andre Przywara <andre.przywara@arm.com>
To: "Arnd Bergmann" <arnd@arndb.de>
Cc: "Naresh Kamboju" <naresh.kamboju@linaro.org>,
"open list" <linux-kernel@vger.kernel.org>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
linux-sunxi@lists.linux.dev, dri-devel@lists.freedesktop.org,
lkft-triage@lists.linaro.org,
"Maxime Ripard" <mripard@kernel.org>,
"Dave Airlie" <airlied@redhat.com>,
"Dan Carpenter" <dan.carpenter@linaro.org>,
"Ard Biesheuvel" <ardb@kernel.org>
Subject: Re: arm: ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/sun4i/sun4i-drm-hdmi.ko] undefined!
Date: Mon, 4 Mar 2024 11:45:46 +0000 [thread overview]
Message-ID: <20240304114546.4e8e1e32@donnerap.manchester.arm.com> (raw)
In-Reply-To: <1baf9a7f-b0e4-45d8-ac57-0727a213d82d@app.fastmail.com>
On Mon, 04 Mar 2024 12:26:46 +0100
"Arnd Bergmann" <arnd@arndb.de> wrote:
> On Mon, Mar 4, 2024, at 12:24, Andre Przywara wrote:
> > On Mon, 04 Mar 2024 12:11:36 +0100 "Arnd Bergmann" <arnd@arndb.de> wrote:
> >>
> >> This used to be a 32-bit division. If the rate is never more than
> >> 4.2GHz, clock could be turned back into 'unsigned long' to avoid
> >> the expensive div_u64().
> >
> > Wouldn't "div_u64(clock, 200)" solve this problem?
>
> Yes, that's why I mentioned it as the worse of the two obvious
> solutions. ;-)
Argh, should have cleaned my glasses first ;-)
I guess I was put somehow put off by the word "expensive". While it's
admittedly not trivial, I wonder if we care about the (hidden) complexity
of that function? I mean it's neither core code nor something called
frequently?
I don't think we have any clock exceeding 3GHz at the moment, but it
sounds fishy to rely on that.
Cheers,
Andre
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next prev parent reply other threads:[~2024-03-04 11:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 8:07 arm: ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/sun4i/sun4i-drm-hdmi.ko] undefined! Naresh Kamboju
2024-03-04 11:11 ` Arnd Bergmann
2024-03-04 11:24 ` Andre Przywara
2024-03-04 11:26 ` Arnd Bergmann
2024-03-04 11:45 ` Andre Przywara [this message]
2024-03-04 12:34 ` Arnd Bergmann
2024-03-04 13:01 ` Ard Biesheuvel
2024-03-04 13:48 ` Arnd Bergmann
2024-03-04 13:55 ` Ard Biesheuvel
2024-03-04 11:46 ` Maxime Ripard
2024-03-09 14:33 ` David Laight
2024-03-14 9:27 ` Geert Uytterhoeven
2024-03-14 11:14 ` Geert Uytterhoeven
2024-03-14 15:04 ` Maxime Ripard
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