Commit b9de01d8 authored by Imre Deak's avatar Imre Deak
Browse files

drm/i915/dp: Simplify intel_dp_max_data_rate() 



Simplify intel_dp_max_data_rate() using
drm_dp_bw_channel_coding_efficiency() to calculate the max data rate for
both DP1.4 and UHBR link rates. This trades a redundant multiply/divide
for readability.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231116131841.1588781-11-imre.deak@intel.com
parent 5ee4badb

drivers/gpu/drm/i915/display/intel_dp.c

+12 −14
Original line number Diff line number Diff line
@@ -405,29 +405,27 @@ int intel_dp_effective_data_rate(int pixel_clock, int bpp_x16, 
int

intel_dp_max_data_rate(int max_link_rate, int max_lanes)

{

	if (max_link_rate >= 1000000) {

	int ch_coding_efficiency =

		drm_dp_bw_channel_coding_efficiency(drm_dp_is_uhbr_rate(max_link_rate));

	int max_link_rate_kbps = max_link_rate * 10;



	/*

	 * UHBR rates always use 128b/132b channel encoding, and have

	 * 97.71% data bandwidth efficiency. Consider max_link_rate the

	 * link bit rate in units of 10000 bps.

	 */

		int max_link_rate_kbps = max_link_rate * 10;



		max_link_rate_kbps = DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate_kbps, 9671), 10000);

		max_link_rate = max_link_rate_kbps / 8;

	}



	/*

	 * Lower than UHBR rates always use 8b/10b channel encoding, and have

	 * 80% data bandwidth efficiency for SST non-FEC. However, this turns

	 * out to be a nop by coincidence, and can be skipped:

	 * out to be a nop by coincidence:

	 *

	 *	int max_link_rate_kbps = max_link_rate * 10;

	 *	max_link_rate_kbps = DIV_ROUND_DOWN_ULL(max_link_rate_kbps * 8, 10);

	 *	max_link_rate = max_link_rate_kbps / 8;

	 */



	return max_link_rate * max_lanes;

	return DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate_kbps * max_lanes,

					      ch_coding_efficiency),

				  1000000 * 8);

}



bool intel_dp_can_bigjoiner(struct intel_dp *intel_dp)