[Intel-gfx] [PATCH 02/15] drm/i915: Don't pass *DP around to link training functions
Ander Conselvan De Oliveira
conselvan2 at gmail.com
Mon Oct 19 01:56:17 PDT 2015
On Mon, 2015-10-19 at 10:15 +0530, Thulasimani, Sivakumar wrote:
>
> On 10/5/2015 12:31 PM, Ander Conselvan de Oliveira wrote:
> > It just makes the code more confusing, so just reference intel_dp_>DP
> > directly. The old behavior of not updating the value in intel_dp if link
> > training fail is preserved by saving the previous value of DP in the
> > stack and restoring the old value in case of failure.
> >
> > Signed-off-by: Ander Conselvan de Oliveira <
> > ander.conselvan.de.oliveira at intel.com>
> > --
> >
> > I'm not sure the old behavior is correct, but to err in the side of
> > caution I tried not to change it.
> >
> > ---
> > drivers/gpu/drm/i915/intel_dp.c | 66 ++++++++++++++++++++-----------------
> > ----
> > 1 file changed, 33 insertions(+), 33 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index c420edf..391a367 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -3601,7 +3601,6 @@ intel_dp_set_signal_levels(struct intel_dp *intel_dp,
> > uint32_t *DP)
> >
> > static bool
> > intel_dp_set_link_train(struct intel_dp *intel_dp,
> > - uint32_t *DP,
> > uint8_t dp_train_pat)
> > {
> > struct intel_digital_port *intel_dig_port =
> > dp_to_dig_port(intel_dp);
> > @@ -3610,9 +3609,9 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
> > uint8_t buf[sizeof(intel_dp->train_set) + 1];
> > int ret, len;
> >
> > - _intel_dp_set_link_train(intel_dp, DP, dp_train_pat);
> > + _intel_dp_set_link_train(intel_dp, &intel_dp->DP, dp_train_pat);
> >
> > - I915_WRITE(intel_dp->output_reg, *DP);
> > + I915_WRITE(intel_dp->output_reg, intel_dp->DP);
> > POSTING_READ(intel_dp->output_reg);
> >
> > buf[0] = dp_train_pat;
> > @@ -3633,17 +3632,17 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
> > }
> >
> > static bool
> > -intel_dp_reset_link_train(struct intel_dp *intel_dp, uint32_t *DP,
> > +intel_dp_reset_link_train(struct intel_dp *intel_dp,
> > uint8_t dp_train_pat)
> > {
> > if (!intel_dp->train_set_valid)
> > memset(intel_dp->train_set, 0, sizeof(intel_dp
> > ->train_set));
> > - intel_dp_set_signal_levels(intel_dp, DP);
> > - return intel_dp_set_link_train(intel_dp, DP, dp_train_pat);
> > + intel_dp_set_signal_levels(intel_dp, &intel_dp->DP);
> > + return intel_dp_set_link_train(intel_dp, dp_train_pat);
> > }
> >
> > static bool
> > -intel_dp_update_link_train(struct intel_dp *intel_dp, uint32_t *DP,
> > +intel_dp_update_link_train(struct intel_dp *intel_dp,
> > const uint8_t link_status[DP_LINK_STATUS_SIZE])
> > {
> > struct intel_digital_port *intel_dig_port =
> > dp_to_dig_port(intel_dp);
> > @@ -3652,9 +3651,9 @@ intel_dp_update_link_train(struct intel_dp *intel_dp,
> > uint32_t *DP,
> > int ret;
> >
> > intel_get_adjust_train(intel_dp, link_status);
> > - intel_dp_set_signal_levels(intel_dp, DP);
> > + intel_dp_set_signal_levels(intel_dp, &intel_dp->DP);
> >
> > - I915_WRITE(intel_dp->output_reg, *DP);
> > + I915_WRITE(intel_dp->output_reg, intel_dp->DP);
> > POSTING_READ(intel_dp->output_reg);
> >
> > ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
> > @@ -3695,7 +3694,7 @@ static void intel_dp_set_idle_link_train(struct
> > intel_dp *intel_dp)
> > }
> >
> > /* Enable corresponding port and start training pattern 1 */
> > -static void
> > +static bool
> > intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > {
> > struct drm_encoder *encoder = &dp_to_dig_port(intel_dp)
> > ->base.base;
> > @@ -3703,9 +3702,9 @@ intel_dp_link_training_clock_recovery(struct intel_dp
> > *intel_dp)
> > int i;
> > uint8_t voltage;
> > int voltage_tries, loop_tries;
> > - uint32_t DP = intel_dp->DP;
> > uint8_t link_config[2];
> > uint8_t link_bw, rate_select;
> > + uint8_t link_status[DP_LINK_STATUS_SIZE];
> >
> > if (HAS_DDI(dev))
> > intel_ddi_prepare_link_retrain(encoder);
> > @@ -3727,22 +3726,20 @@ intel_dp_link_training_clock_recovery(struct
> > intel_dp *intel_dp)
> > link_config[1] = DP_SET_ANSI_8B10B;
> > drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config,
> > 2);
> >
> > - DP |= DP_PORT_EN;
> > + intel_dp->DP |= DP_PORT_EN;
> >
> > /* clock recovery */
> > - if (!intel_dp_reset_link_train(intel_dp, &DP,
> > + if (!intel_dp_reset_link_train(intel_dp,
> > DP_TRAINING_PATTERN_1 |
> > DP_LINK_SCRAMBLING_DISABLE)) {
> > DRM_ERROR("failed to enable link training\n");
> > - return;
> > + return false;
> > }
> >
> > voltage = 0xff;
> > voltage_tries = 0;
> > loop_tries = 0;
> > for (;;) {
> > - uint8_t link_status[DP_LINK_STATUS_SIZE];
> > -
> > drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
> > if (!intel_dp_get_link_status(intel_dp, link_status)) {
> > DRM_ERROR("failed to get link status\n");
> > @@ -3762,11 +3759,11 @@ intel_dp_link_training_clock_recovery(struct
> > intel_dp *intel_dp)
> > DRM_DEBUG_KMS("clock recovery not ok, reset");
> > /* clear the flag as we are not reusing train set
> > */
> > intel_dp->train_set_valid = false;
> > - if (!intel_dp_reset_link_train(intel_dp, &DP,
> > + if (!intel_dp_reset_link_train(intel_dp,
> >
> > DP_TRAINING_PATTERN_1 |
> >
> > DP_LINK_SCRAMBLING_DISABLE)) {
> > DRM_ERROR("failed to enable link
> > training\n");
> > - return;
> > + return false;
> > }
> > continue;
> > }
> > @@ -3781,7 +3778,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp
> > *intel_dp)
> > DRM_ERROR("too many full retries, give
> > up\n");
> > break;
> > }
> > - intel_dp_reset_link_train(intel_dp, &DP,
> > + intel_dp_reset_link_train(intel_dp,
> > DP_TRAINING_PATTERN_1 |
> >
> > DP_LINK_SCRAMBLING_DISABLE);
> > voltage_tries = 0;
> > @@ -3800,23 +3797,22 @@ intel_dp_link_training_clock_recovery(struct
> > intel_dp *intel_dp)
> > voltage = intel_dp->train_set[0] &
> > DP_TRAIN_VOLTAGE_SWING_MASK;
> >
> > /* Update training set as requested by target */
> > - if (!intel_dp_update_link_train(intel_dp, &DP,
> > link_status)) {
> > + if (!intel_dp_update_link_train(intel_dp, link_status)) {
> > DRM_ERROR("failed to update link training\n");
> > break;
> > }
> > }
> >
> > - intel_dp->DP = DP;
> > + return drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count);
> why are we calling the same function again? in best case this function
> is called and returned true,
> or worst case it was never called. so it will be simpler if we store
> the return value of this function
> inside the loop and return that here ?
I missed this comment earlier. I don't think calling drm_dp_clock_recovery_ok()
would have a big impact, since it is a very simple function. But I can add a
variable if that is preferred.
Ander
> > }
> >
> > -static void
> > +static bool
> > intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > {
> > struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > struct drm_device *dev = dig_port->base.base.dev;
> > bool channel_eq = false;
> > int tries, cr_tries;
> > - uint32_t DP = intel_dp->DP;
> > uint32_t training_pattern = DP_TRAINING_PATTERN_2;
> >
> > /*
> > @@ -3835,11 +3831,11 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > DRM_ERROR("5.4 Gbps link rate without HBR2/TPS3
> > support\n");
> >
> > /* channel equalization */
> > - if (!intel_dp_set_link_train(intel_dp, &DP,
> > + if (!intel_dp_set_link_train(intel_dp,
> > training_pattern |
> > DP_LINK_SCRAMBLING_DISABLE)) {
> > DRM_ERROR("failed to start channel equalization\n");
> > - return;
> > + return false;
> > }
> >
> > tries = 0;
> > @@ -3864,7 +3860,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > intel_dp->lane_count)) {
> > intel_dp->train_set_valid = false;
> > intel_dp_link_training_clock_recovery(intel_dp);
> > - intel_dp_set_link_train(intel_dp, &DP,
> > + intel_dp_set_link_train(intel_dp,
> > training_pattern |
> > DP_LINK_SCRAMBLING_DISABLE
> > );
> > cr_tries++;
> > @@ -3881,7 +3877,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > if (tries > 5) {
> > intel_dp->train_set_valid = false;
> > intel_dp_link_training_clock_recovery(intel_dp);
> > - intel_dp_set_link_train(intel_dp, &DP,
> > + intel_dp_set_link_train(intel_dp,
> > training_pattern |
> > DP_LINK_SCRAMBLING_DISABLE
> > );
> > tries = 0;
> > @@ -3890,7 +3886,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > }
> >
> > /* Update training set as requested by target */
> > - if (!intel_dp_update_link_train(intel_dp, &DP,
> > link_status)) {
> > + if (!intel_dp_update_link_train(intel_dp, link_status)) {
> > DRM_ERROR("failed to update link training\n");
> > break;
> > }
> > @@ -3899,25 +3895,29 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> >
> > intel_dp_set_idle_link_train(intel_dp);
> >
> > - intel_dp->DP = DP;
> > -
> > if (channel_eq) {
> > intel_dp->train_set_valid = true;
> > DRM_DEBUG_KMS("Channel EQ done. DP Training
> > successful\n");
> > + return true;
> > + } else {
> > + return false;
> > }
> > }
> >
> > void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> > {
> > - intel_dp_set_link_train(intel_dp, &intel_dp->DP,
> > + intel_dp_set_link_train(intel_dp,
> > DP_TRAINING_PATTERN_DISABLE);
> > }
> >
> > void
> > intel_dp_start_link_train(struct intel_dp *intel_dp)
> > {
> > - intel_dp_link_training_clock_recovery(intel_dp);
> > - intel_dp_link_training_channel_equalization(intel_dp);
> > + uint32_t DP = intel_dp->DP;
> > +
> > + if (!intel_dp_link_training_clock_recovery(intel_dp) ||
> > + !intel_dp_link_training_channel_equalization(intel_dp))
> > + intel_dp->DP = DP;
> it is wrong to restore the value of DP here, we have modified the value
> of port/ddi already inside the two functions.
> if either of these two steps fail we should call stop link training and
> follow it with bspec disable sequence.
> so saving and restoring will not help us in anyway but more hide the
> real status of HW.
> > }
> >
> > static void
>
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