On Fri, Jul 10, 2026 at 3:44 AM <[email protected]> wrote:
>
> From: yanglinlin <[email protected]>
>
> When compiling the AMDGPU display driver for 32-bit architectures,
> the linker reports undefined reference to `__udivdi3` in functions
> get_dp_dto_frequency_100hz() and dcn401_get_dp_dto_frequency_100hz().
>
> This is because the code uses 64-bit division (/) on 32-bit systems,
> which GCC cannot handle directly and instead tries to call the missing
> __udivdi3 helper function.
>
> Replace the raw division with div_u64(), the kernel's standard 64-bit
> division helper, to avoid the link error.
>
> Signed-off-by: yanglinlin <[email protected]>
> ---
> drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> index 7c293917e6fd..9dfb6f132136 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> @@ -1229,9 +1229,9 @@ static bool get_dp_dto_frequency_100hz(
> */
> modulo_hz = REG_READ(MODULO[inst]);
> if (modulo_hz) {
> - temp = div_u64((uint64_t)clock_hz *
> dp_dto_ref_khz * 10, modulo_hz);
> - ASSERT(temp / 100 <= 0xFFFFFFFFUL);
> - *pixel_clk_100hz = (unsigned int)(temp / 100);
> + temp = clock_hz * dp_dto_ref_khz * 10;
> + ASSERT(temp <= INT_MAX * modulo_hz * 100);
Shouldn't this be UINT_MAX?
Alex
> + *pixel_clk_100hz = div_u64(temp, modulo_hz *
> 100);
> } else
> *pixel_clk_100hz = 0;
> } else {
> @@ -1285,13 +1285,12 @@ static bool dcn401_get_dp_dto_frequency_100hz(const
> struct clock_source *clock_s
> * - target pix_clk_hz = (DPDTO INTEGER * DPDTO MODULO +
> DPDTO PHASE)
> */
> temp = (unsigned long long)dp_dto_integer * modulo_hz +
> phase_hz;
> -
> - if (temp / 100 > 0xFFFFFFFFUL) {
> + if (temp > (UINT_MAX * 100ULL)) {
> /* pixel rate 100hz should never be this high, if it
> is, throw an assert and return 0 */
> BREAK_TO_DEBUGGER();
> *pixel_clk_100hz = 0;
> } else {
> - *pixel_clk_100hz = (unsigned int)(temp / 100);
> + *pixel_clk_100hz = div_u64(temp, 100);
> }
>
> return true;
> --
> 2.25.1
>
