Please ignore this patchset, it's not yet the correct version rebased on v5.11 (more precisely I Cc'd stable for this version of the patchset by mistake). I'll resend this patchset properly rebased on v5.11. Sorry for the noise. --Imre On Fri, Apr 02, 2021 at 02:29:24AM +0300, Imre Deak wrote: > The spec requires to use at least 3.2ms for the AUX timeout period if > there are LT-tunable PHY Repeaters on the link (2.11.2). An upcoming > spec update makes this more specific, by requiring a 3.2ms minimum > timeout period for the LTTPR detection reading the 0xF0000-0xF0007 > range (3.6.5.1). > > Accordingly disable LTTPR detection until GLK, where the maximum timeout > we can set is only 1.6ms. > > Link training in the non-transparent mode is known to fail at least on > some SKL systems with a WD19 dock on the link, which exposes an LTTPR > (see the References below). While this could have different reasons > besides the too short AUX timeout used, not detecting LTTPRs (and so not > using the non-transparent LT mode) fixes link training on these systems. > > While at it add a code comment about the platform specific maximum > timeout values. > > v2: Add a comment about the g4x maximum timeout as well. (Ville) > > Reported-by: Takashi Iwai <tiwai@xxxxxxx> > Reported-and-tested-by: Santiago Zarate <santiago.zarate@xxxxxxxx> > Reported-and-tested-by: Bodo Graumann <mail@xxxxxxxxxxxxxxx> > References: https://gitlab.freedesktop.org/drm/intel/-/issues/3166 > Fixes: b30edfd8d0b4 ("drm/i915: Switch to LTTPR non-transparent mode link training") > Cc: <stable@xxxxxxxxxxxxxxx> # v5.11 > Cc: Takashi Iwai <tiwai@xxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Link: https://patchwork.freedesktop.org/patch/msgid/20210317184901.4029798-2-imre.deak@xxxxxxxxx > (cherry picked from commit 984982f3ef7b240cd24c2feb2762d81d9d8da3c2) > --- > drivers/gpu/drm/i915/display/intel_dp_aux.c | 7 +++++++ > .../gpu/drm/i915/display/intel_dp_link_training.c | 15 ++++++++++++--- > 2 files changed, 19 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c > index eaebf123310a..10fe17b7280d 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > @@ -133,6 +133,7 @@ static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp, > else > precharge = 5; > > + /* Max timeout value on G4x-BDW: 1.6ms */ > if (IS_BROADWELL(dev_priv)) > timeout = DP_AUX_CH_CTL_TIME_OUT_600us; > else > @@ -159,6 +160,12 @@ static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp, > enum phy phy = intel_port_to_phy(i915, dig_port->base.port); > u32 ret; > > + /* > + * Max timeout values: > + * SKL-GLK: 1.6ms > + * CNL: 3.2ms > + * ICL+: 4ms > + */ > ret = DP_AUX_CH_CTL_SEND_BUSY | > DP_AUX_CH_CTL_DONE | > DP_AUX_CH_CTL_INTERRUPT | > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > index 892d7db7d94f..35cda72492d7 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > @@ -81,6 +81,18 @@ static void intel_dp_read_lttpr_phy_caps(struct intel_dp *intel_dp, > > static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp) > { > + struct drm_i915_private *i915 = dp_to_i915(intel_dp); > + > + if (intel_dp_is_edp(intel_dp)) > + return false; > + > + /* > + * Detecting LTTPRs must be avoided on platforms with an AUX timeout > + * period < 3.2ms. (see DP Standard v2.0, 2.11.2, 3.6.6.1). > + */ > + if (INTEL_GEN(i915) < 10) > + return false; > + > if (drm_dp_read_lttpr_common_caps(&intel_dp->aux, > intel_dp->lttpr_common_caps) < 0) { > memset(intel_dp->lttpr_common_caps, 0, > @@ -126,9 +138,6 @@ int intel_dp_lttpr_init(struct intel_dp *intel_dp) > bool ret; > int i; > > - if (intel_dp_is_edp(intel_dp)) > - return 0; > - > ret = intel_dp_read_lttpr_common_caps(intel_dp); > if (!ret) > return 0;
