linux-kernel - Re: [PATCH] drm/amd/display: fix 64-bit integer division

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Date:   Thu, 25 Feb 2021 21:39:47 +0000
From:   "Stempen, Vladimir" <Vladimir.Stempen@....com>
To:     Arnd Bergmann <arnd@...nel.org>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, "R, Bindu" <Bindu.R@....com>
CC:     Arnd Bergmann <arnd@...db.de>,
        "Siqueira, Rodrigo" <Rodrigo.Siqueira@....com>,
        "Laktyushkin, Dmytro" <Dmytro.Laktyushkin@....com>,
        "Pillai, Aurabindo" <Aurabindo.Pillai@....com>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/amd/display: fix 64-bit integer division

[AMD Official Use Only - Internal Distribution Only]

Hi Arnd,
I have all the patches ready and I have tested them with the feature/platform I'm working on and Bindu helped to test the 32bit build.
I'm in process of submitting the latest change.
Thanks,
Vladimir.

On 2021-02-25, 4:36 PM, "Arnd Bergmann" <arnd@...nel.org> wrote:

    On Thu, Feb 25, 2021 at 3:33 PM Arnd Bergmann <arnd@...nel.org> wrote:
    >
    > From: Arnd Bergmann <arnd@...db.de>
    >
    > The new display synchronization code caused a regression
    > on all 32-bit architectures:
    >
    > ld.lld: error: undefined symbol: __aeabi_uldivmod
    > >>> referenced by dce_clock_source.c
    > >>>               gpu/drm/amd/display/dc/dce/dce_clock_source.o:(get_pixel_clk_frequency_100hz) in archive drivers/built-in.a
    >
    > ld.lld: error: undefined symbol: __aeabi_ldivmod
    > >>> referenced by dc_resource.c
    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a
    > >>> referenced by dc_resource.c
    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a
    > >>> referenced by dc_resource.c
    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a
    >
    > This is not a fast path, so the use of an explicit div_u64/div_s64
    > seems appropriate.

    I found two more instances:

    >>> referenced by dcn20_optc.c
    >>>               gpu/drm/amd/display/dc/dcn20/dcn20_optc.o:(optc2_align_vblanks) in archive drivers/built-in.a

    >>> referenced by dcn10_hw_sequencer.c
    >>>               gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.o:(reduceSizeAndFraction) in archive drivers/built-in.a

    I have patches for both, but will let the randconfig build box keep working
    on it over night to see if there are any others. Let me know if you want a
    combined patch or one per file once there are no more regressions.

            Arnd