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Open Source and information security mailing list archives
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Date: Mon, 4 Mar 2024 11:45:46 +0000 From: Andre Przywara <andre.przywara@....com> To: "Arnd Bergmann" <arnd@...db.de> Cc: "Naresh Kamboju" <naresh.kamboju@...aro.org>, "open list" <linux-kernel@...r.kernel.org>, "Linux ARM" <linux-arm-kernel@...ts.infradead.org>, linux-sunxi@...ts.linux.dev, dri-devel@...ts.freedesktop.org, lkft-triage@...ts.linaro.org, "Maxime Ripard" <mripard@...nel.org>, "Dave Airlie" <airlied@...hat.com>, "Dan Carpenter" <dan.carpenter@...aro.org>, "Ard Biesheuvel" <ardb@...nel.org> Subject: Re: arm: ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/sun4i/sun4i-drm-hdmi.ko] undefined! On Mon, 04 Mar 2024 12:26:46 +0100 "Arnd Bergmann" <arnd@...db.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@...db.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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