Hello Srikanth, Thank you for the review. > -----Original Message----- > From: Srikanth V, NagaVenkata <nagavenkata.srikanth.v@xxxxxxxxx> > Sent: Monday, September 23, 2024 4:16 PM > To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>; intel- > gfx@xxxxxxxxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx > Subject: RE: [PATCH] drm/i915/dp: Add FEC Enable Retry mechanism > > > > > -----Original Message----- > > From: Intel-xe <intel-xe-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of > > Chaitanya Kumar Borah > > Sent: Monday, September 23, 2024 10:22 AM > > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx > > Subject: [PATCH] drm/i915/dp: Add FEC Enable Retry mechanism > > > > From PTL, FEC_DECODE_EN sequence can be sent to a DPRX independent of > > TRANS_CONF enable. This allows us to re-issue an FEC_DECODE_EN > > sequence without re-doing the whole mode set sequence. This separate > > control over FEC_ECODE_EN/DIS sequence enables us to have a retry > > mechanism in case the DPRX does not respond with an FEC_ENABLE within > the stipulated 5ms. > > > > Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/display/intel_ddi.c | 61 > > +++++++++++++++++++++++- > > 1 file changed, 59 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c > > b/drivers/gpu/drm/i915/display/intel_ddi.c > > index 85e519a21542..589acea9906a 100644 > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c > > @@ -78,6 +78,8 @@ > > #include "skl_scaler.h" > > #include "skl_universal_plane.h" > > > > +#define FEC_RETRY_COUNT 3 > > + > > static const u8 index_to_dp_signal_levels[] = { > > [0] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | > DP_TRAIN_PRE_EMPH_LEVEL_0, > > [1] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | > DP_TRAIN_PRE_EMPH_LEVEL_1, @@ > > -2255,6 +2257,57 @@ static int read_fec_detected_status(struct > > drm_dp_aux *aux) > > return status; > > } > > > > +static void retry_fec_enable(struct intel_encoder *encoder, > > + const struct intel_crtc_state *crtc_state, > > + struct drm_dp_aux *aux) > > +{ > > + struct drm_i915_private *i915 = to_i915(aux->drm_dev); > > + int ret = 0; > > + > > You should also be clearing FEC_ENABLE_LIVE_STATUS in DP_TP_STATUS > register by writing 1. > This seems to be a RO bit according to spec. > > + /* Clear FEC enable */ > > + intel_de_rmw(i915, dp_tp_ctl_reg(encoder, crtc_state), > > + DP_TP_CTL_FEC_ENABLE, 0); > > + > > > + /* Set FEC enable */ > > + intel_de_rmw(i915, dp_tp_ctl_reg(encoder, crtc_state), > > + 0, DP_TP_CTL_FEC_ENABLE); > > + > > + ret = intel_de_wait_for_set(i915, dp_tp_status_reg(encoder, > > crtc_state), > > + DP_TP_STATUS_FEC_ENABLE_LIVE, 1); > > + if (!ret) > > + drm_dbg_kms(&i915->drm, > > + "Timeout waiting for FEC live state to get enabled"); > } > > + > > +static void wait_for_fec_detected_with_retry(struct intel_encoder > *encoder, > > + const struct intel_crtc_state > > *crtc_state, > > + struct drm_dp_aux *aux) > > +{ > > + struct drm_i915_private *i915 = to_i915(aux->drm_dev); > > + int status; > > + int err; > > + int retrycount = 0; > > + > > + do { > > + err = readx_poll_timeout(read_fec_detected_status, aux, > > status, > > + status & > > DP_FEC_DECODE_EN_DETECTED || status < 0, > > + 500, 5000); > > + > > + if (!err && status >= 0) > > + return; > > + > > + if (err == -ETIMEDOUT) { > > + drm_dbg_kms(&i915->drm, > > + "Timeout waiting for FEC ENABLE to get > > detected, retrying\n"); > > + retry_fec_enable(encoder, crtc_state, aux); > > + } else { > > + drm_dbg_kms(&i915->drm, "FEC detected status > read > > error: %d\n", status); > > + } > > + } while (retrycount++ < FEC_RETRY_COUNT); > > + > > + drm_err(&i915->drm, "FEC enable Failed after Retry\n"); } > > + > > static void wait_for_fec_detected(struct drm_dp_aux *aux, bool enabled) { > > struct drm_i915_private *i915 = to_i915(aux->drm_dev); @@ - > 2303,8 > > +2356,12 @@ void intel_ddi_wait_for_fec_status(struct intel_encoder > > *encoder, > > * At least the Synoptics MST hub doesn't set the detected flag for > > * FEC decoding disabling so skip waiting for that. > > */ > > - if (enabled) > > - wait_for_fec_detected(&intel_dp->aux, enabled); > > + if (enabled) { > > + if (DISPLAY_VER(i915) >= 30) > > + wait_for_fec_detected_with_retry(encoder, > crtc_state, > > &intel_dp->aux); > > wait_for_fec_detected_with_retry() should be called inside > intel_ddi_enable_fec() after configuring DP_TP_CTL register and before > transcoder is enabled. > wait_for_fec_detected() is called after transcoder is enabled. > Agreed. I will make the change. Regards Chaitanya > > + else > > + wait_for_fec_detected(&intel_dp->aux, enabled); > > + } > > } > > > > static void intel_ddi_enable_fec(struct intel_encoder *encoder, > > -- > > 2.25.1