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: Linlin Yang <[email protected]> Reported-by: k2ci <[email protected]> --- v1 -> v2: Adjust overflow‑check condition: change INT_MAX to UINT_MAX and add 100ULL suffix, also reorganize calculation order to avoid potential integer overflow 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..ecb8493ec523 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 <= UINT_MAX * modulo_hz * 100ULL); + *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
