Re: arm: ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/sun4i/sun4i-drm-hdmi.ko] undefined!

Maxime Ripard
2024-03-04T11:46:22Z

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Hi,

On Mon, Mar 04, 2024 at 12:11:36PM +0100, Arnd Bergmann wrote:
> On Mon, Mar 4, 2024, at 09:07, Naresh Kamboju wrote:
> > The arm defconfig builds failed on today's Linux next tag next-20240304.
> >
> > Build log:
> > ---------
> > ERROR: modpost: "__aeabi_uldivmod"
> > [drivers/gpu/drm/sun4i/sun4i-drm-hdmi.ko] undefined!
> >
>
> Apparently caused by the 64-bit division in 358e76fd613a
> ("drm/sun4i: hdmi: Consolidate atomic_check and mode_valid"):
>
>
> +static enum drm_mode_status
> +sun4i_hdmi_connector_clock_valid(const struct drm_connector *connector,
> + const struct drm_display_mode *mode,
> + unsigned long long clock)
> {
> - struct sun4i_hdmi *hdmi = drm_encoder_to_sun4i_hdmi(encoder);
> - unsigned long rate = mode->clock * 1000;
> - unsigned long diff = rate / 200; /* +-0.5% allowed by HDMI spec */
> + const struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
> + unsigned long diff = clock / 200; /* +-0.5% allowed by HDMI spec */
> long rounded_rate;
>
> 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().

I sent a fix for it this morning:
https://lore.kernel.org/r/20240304091225.366325-1-mripard@kernel.org

The framework will pass an unsigned long long because HDMI character
rates can go up to 5.9GHz.

Maxime

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