From: Maxime Ripard
Sent: 04 March 2024 11:46
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.
You could do: /* The max clock is 5.9GHz, split the divide */ u32 diff = (u32)(clock / 8) / (200/8);
The code should really use u32 and u64. Otherwise the sizes are different on 32bit.
David
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