On Tue, Oct 24, 2023 at 04:09:06AM +0300, Imre Deak wrote:
> A follow-up patch will add up all the overheads on a DP link, where it
> makes more sense to specify each overhead factor in terms of the added
> overhead amount vs. the reciprocal remainder (of usable BW remaining
> after deducting the overhead). Prepare for that here, keeping the
> existing behavior.
>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 2048649b420b2..0c0f026fb3161 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -85,8 +85,8 @@
> #define DP_DSC_MAX_ENC_THROUGHPUT_0 340000
> #define DP_DSC_MAX_ENC_THROUGHPUT_1 400000
>
> -/* DP DSC FEC Overhead factor = 1/(0.972261) */
> -#define DP_DSC_FEC_OVERHEAD_FACTOR 972261
> +/* DP DSC FEC Overhead factor = 1/(0.972261) = 1.028530 ppm */
> +#define DP_DSC_FEC_OVERHEAD_FACTOR 1028530
>
> /* Compliance test status bits */
> #define INTEL_DP_RESOLUTION_SHIFT_MASK 0
> @@ -680,8 +680,8 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
>
> u32 intel_dp_mode_to_fec_clock(u32 mode_clock)
> {
> - return div_u64(mul_u32_u32(mode_clock, 1000000U),
> - DP_DSC_FEC_OVERHEAD_FACTOR);
> + return div_u64(mul_u32_u32(mode_clock, DP_DSC_FEC_OVERHEAD_FACTOR),
> + 1000000U);
> }
>
> static int
> --
> 2.39.2
>
