On Tue, 22 Dec 2015, Lukas Wunner <lukas@xxxxxxxxx> wrote: > Hi Mika, > > On Mon, Dec 21, 2015 at 01:39:15PM +0200, Mika Kahola wrote: >> Check if no AUX transactions are required on DP link training. >> If this bit is set, we can reuse the known good drive current >> and pre-emphasis level from the last "full" link training. >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91393 >> Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx> >> --- >> drivers/gpu/drm/i915/intel_dp.c | 2 +- >> drivers/gpu/drm/i915/intel_dp_link_training.c | 19 +++++++++++++++++++ >> drivers/gpu/drm/i915/intel_drv.h | 1 + >> 3 files changed, 21 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c >> index 6b36d82..3137187 100644 >> --- a/drivers/gpu/drm/i915/intel_dp.c >> +++ b/drivers/gpu/drm/i915/intel_dp.c >> @@ -3852,7 +3852,7 @@ intel_dp_link_down(struct intel_dp *intel_dp) >> intel_dp->DP = DP; >> } >> >> -static bool >> +bool >> intel_dp_get_dpcd(struct intel_dp *intel_dp) >> { >> struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp); >> diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c >> index 59d59be..5fb3f97 100644 >> --- a/drivers/gpu/drm/i915/intel_dp_link_training.c >> +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c >> @@ -85,6 +85,25 @@ static bool >> intel_dp_reset_link_train(struct intel_dp *intel_dp, >> uint8_t dp_train_pat) >> { >> + bool has_dpcd; >> + bool no_aux_handshake = false; >> + >> + has_dpcd = intel_dp_get_dpcd(intel_dp); >> + >> + /* >> + * Source device can try to use drive current and pre-emphasis >> + * parameters computed by the last "full" link training if the >> + * DP_NO_AUX_HANDSHAKE_LINK_TRAINING bit is set to 1. >> + */ >> + if (has_dpcd) { >> + if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11) { >> + no_aux_handshake = (intel_dp->dpcd[DP_MAX_DOWNSPREAD] & >> + DP_NO_AUX_HANDSHAKE_LINK_TRAINING); >> + } >> + } >> + >> + intel_dp->train_set_valid &= no_aux_handshake; >> + > > If Thierry Reding's patches get merged (posted to dri-devel@ on Dec 14 > with <1450097764-30063-1-git-send-email-thierry.reding@xxxxxxxxx>), > you could just use > > if (has_dpcd && drm_dp_fast_training_cap(intel_dp->dpcd)) > intel_dp->train_set_valid &= true; > > Also, if the patches get merged, the no_aux_handshake attribute in dev_priv > can be dropped (set in intel_edp_init_connector() but never read). Good points, but we don't generally write code, let alone bugfixes, on top of code that hasn't been merged. BR, Jani. > > Best regards, > > Lukas > >> DRM_DEBUG_KMS("link training optimization: %s\n", >> intel_dp->train_set_valid ? "true" : "false"); >> >> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h >> index d523ebb..c36a70c 100644 >> --- a/drivers/gpu/drm/i915/intel_drv.h >> +++ b/drivers/gpu/drm/i915/intel_drv.h >> @@ -1239,6 +1239,7 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc); >> bool intel_dp_compute_config(struct intel_encoder *encoder, >> struct intel_crtc_state *pipe_config); >> bool intel_dp_is_edp(struct drm_device *dev, enum port port); >> +bool intel_dp_get_dpcd(struct intel_dp *intel_dp); >> enum irqreturn intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, >> bool long_hpd); >> void intel_edp_backlight_on(struct intel_dp *intel_dp); >> -- >> 1.9.1 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
