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

Arnd Bergmann
2024-03-04T11:12:21Z

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().

Arnd