Only use the table when the link rate is listed (idx valid) and the LTTPR count is within the table bounds. A zero entry means the rate has no tabulated value, so fall back to the computed establishment period below.
Note: The table and its values are taken from DP2.1 vesa spec. v2: Add check for negative error codes from drm_dp_lttpr_count(). [sashiko] Cc: Jouni Högander <[email protected]> Signed-off-by: Animesh Manna <[email protected]> --- drivers/gpu/drm/i915/display/intel_alpm.c | 95 +++++++++++++++++++++++ 1 file changed, 95 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c b/drivers/gpu/drm/i915/display/intel_alpm.c index dc025058a626..cb24bba801a1 100644 --- a/drivers/gpu/drm/i915/display/intel_alpm.c +++ b/drivers/gpu/drm/i915/display/intel_alpm.c @@ -122,6 +122,92 @@ static int get_dp_link_symbol_size(const struct intel_crtc_state *crtc_state) return intel_dp_is_uhbr(crtc_state) ? 32 : 10; } +#define DEFAULT_MAX_LTTPR_COUNT 7 +#define MAX_SUPPORTED_DP_LINK_RATES 12 + +static const u32 establishment_periods[DEFAULT_MAX_LTTPR_COUNT][MAX_SUPPORTED_DP_LINK_RATES] = { + /* 1620, 2160, 2430, 2700, 3240, 4320, 5400, 6750, 8100, 10000, 13500, 20000 */ + /* No Retimers */ + { 61070, 0, 0, 56710, 0, 0, 53450, 0, 52360, 59050, 56750, 54620 }, + /* 1 Retimer */ + { 155670, 0, 0, 151310, 0, 0, 148050, 0, 146960, 153650, 151350, 149220 }, + /* 2 Retimers */ + { 181160, 0, 0, 172450, 0, 0, 165910, 0, 163740, 177120, 172520, 168220 }, + /* 3 Retimers */ + { 206650, 0, 0, 193580, 0, 0, 183780, 0, 180510, 200590, 193690, 187290 }, + /* 4 Retimers */ + { 232140, 0, 0, 214710, 0, 0, 201650, 0, 197290, 224060, 214860, 206320 }, + /* 5 Retimers */ + { 257620, 0, 0, 235850, 0, 0, 219510, 0, 214070, 247530, 236030, 225360 }, + /* 6 Retimers */ + { 283110, 0, 0, 256980, 0, 0, 237380, 0, 230850, 271000, 257200, 244390 }, +}; + +enum link_rate_idx { + LINK_RATE_INVALID = -1, + LINK_RATE_1, + LINK_RATE_2, + LINK_RATE_3, + LINK_RATE_4, + LINK_RATE_5, + LINK_RATE_6, + LINK_RATE_7, + LINK_RATE_8, + LINK_RATE_9, + LINK_RATE_10, + LINK_RATE_11, + LINK_RATE_12 +}; + +static int get_link_rate_index(int port_clock) +{ + int link_rate_index; + + switch (port_clock) { + case 162000: + link_rate_index = LINK_RATE_1; // Rate_1 (RBR) - 1.62 Gbps/Lane + break; + case 216000: + link_rate_index = LINK_RATE_2; // Rate_2 - 2.16 Gbps/Lane + break; + case 243000: + link_rate_index = LINK_RATE_3; // Rate_3 - 2.43 Gbps/Lane + break; + case 270000: + link_rate_index = LINK_RATE_4; // Rate_4 (HBR) - 2.70 Gbps/Lane + break; + case 324000: + link_rate_index = LINK_RATE_5; // Rate_5 (RBR2)- 3.24 Gbps/Lane + break; + case 432000: + link_rate_index = LINK_RATE_6; // Rate_6 - 4.32 Gbps/Lane + break; + case 540000: + link_rate_index = LINK_RATE_7; // Rate_7 (HBR2)- 5.40 Gbps/Lane + break; + case 675000: + link_rate_index = LINK_RATE_8; // Rate_8 - 6.75 Gbps/Lane + break; + case 810000: + link_rate_index = LINK_RATE_9; // Rate_9 (HBR3)- 8.10 Gbps/Lane + break; + case 1000000: + link_rate_index = LINK_RATE_10; // Rate_10 (UHBR10) - 10.0 Gbps/Lane + break; + case 1350000: + link_rate_index = LINK_RATE_11; // Rate_11 (UHBR13.5) - 13.5 Gbps/Lane + break; + case 2000000: + link_rate_index = LINK_RATE_12; // Rate_12 (UHBR20) - 20.0 Gbps/Lane + break; + default: + link_rate_index = LINK_RATE_INVALID; + break; + } + + return link_rate_index; +} + static int get_establishment_period(struct intel_dp *intel_dp, const struct intel_crtc_state *crtc_state) { @@ -138,8 +224,17 @@ static int get_establishment_period(struct intel_dp *intel_dp, if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_EDP)) { tcds = (7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1) * tml_phy_lock; } else { + int idx = get_link_rate_index(crtc_state->port_clock); + tcds = 7 * tml_phy_lock; lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps); + + if (idx != LINK_RATE_INVALID && lttpr_count >= 0 && + lttpr_count < DEFAULT_MAX_LTTPR_COUNT && + establishment_periods[lttpr_count][idx]) { + establishment_period = establishment_periods[lttpr_count][idx]; + return establishment_period; + } } if (lttpr_count > 0) { -- 2.29.0
