drm/i915/dp: fix integer overflow in 128b/132b data rate calculation

The intermediate value 1000000 * 10 * 9671 overflows 32 bits, so force
promotion to a bigger type.

From the logs:

[drm:intel_dp_compute_config [i915]] DP link rate required 3657063 available -580783288

v2: Use mul_u32_u32() (Ville)

Fixes: 48efd014f0ea ("drm/i915/dp: add max data rate calculation for UHBR rates")
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211026093407.11381-1-jani.nikula@intel.com
(cherry picked from commit bf0d608b55d9b7f426031dfd9f08d9df36c94728)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Jani Nikula 2021-10-26 12:34:07 +03:00 committed by Rodrigo Vivi
parent 9ca8bb7a1d
commit 02295cf389

@ -287,7 +287,7 @@ intel_dp_max_data_rate(int max_link_rate, int max_lanes)
*/
int max_link_rate_kbps = max_link_rate * 10;
max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(max_link_rate_kbps * 9671, 10000);
max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(max_link_rate_kbps, 9671), 10000);
max_link_rate = max_link_rate_kbps / 8;
}