On Tue, 2026-08-25 at 11:15 +0530, Animesh Manna wrote: > 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.
Where these numbers are coming from? BR, Jouni Högander > > 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 af2733805505..078e04bb69d2 100644 > --- a/drivers/gpu/drm/i915/display/intel_alpm.c > +++ b/drivers/gpu/drm/i915/display/intel_alpm.c > @@ -115,6 +115,92 @@ static int get_tphy2_p2_to_p0(const struct > intel_crtc_state *crtc_state) > return DISPLAY_VER(display) >= 35 ? (20 * 1000) : (12 * > 1000); > } > > +#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 = -1; > + break; > + } > + > + return link_rate_index; > +} > + > static int get_establishment_period(struct intel_dp *intel_dp, > const struct intel_crtc_state > *crtc_state) > { > @@ -129,8 +215,17 @@ 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 < DEFAULT_MAX_LTTPR_COUNT && > + establishment_periods[lttpr_count][idx]) { > + establishment_period = > establishment_periods[lttpr_count][idx]; > + return establishment_period; > + } > } > > if (lttpr_count) {
